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CHANGELOG
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1/**@page RN90 Release notes for SCIP 9
2
3@section RN901 SCIP 9.0.1
4*************************
5
6Fixed bugs
7----------
8
9- fixed bug in detection of double lex matrices due to wrong memory allocation
10- fixed bug where parameter `limits/objectivestop` was copied to subscips in plugins which have different objectives
11- in count mode respect empty solution when problem is solved in presolving
12- fixed that SCIP may have tried to pass a negative random seed to an LP solver
13- fixed bug where conflict analysis in strong branching tried to analyze an unsuccessful LP solve
14- enable parameter limits/restarts by allowing to reach the restart limit in restartAllowed()
15- handle normalizing linear constraints in presolving with more caution to avoid numerical difficulties for integer variables with large coefficients
16- use quad precision to calculate residual activity bounds to reduce numerical errors for large variable bounds in cons_linear.c
17- in SCIPsolveProbingLP() when objective has been changed do not return cutoff due to exceeding the cutoff bound
18- set probing LP to be a relaxation only when objective has not been changed
19- declare contradicting infinities in getMinActivity() and getMaxActivity() as non-tight
20- reject farkas solution with large values to bound magnification of errors in SCIPgetFarkasProof()
21- if all variables are fixed, apply relative feasibility tolerance to avoid invalid infeasibility in applyFixings() of cons_linear.c
22- delete empty redundant knapsack and linear constraints after cleanup in SCIPmatrixCreate()
23- cleanup first constraints in SCIPcleanupConssVarbound(), SCIPcleanupConssSetppc(), and SCIPcleanupConssLogicor()
24- symmetry handling methods have not been added immediately after computing symmetries, which has been fixed
25- delay checking node limits after presolving to correctly continue up to the exceeding main node
26- simplified the objective sense assumption for the subproblems in the Lagromory separator
27- update effective root depth iteratively to avoid trapping it at a single child node
28- fixed that dualsparsify presolver did not always check do-not-multiaggregate variable flag
29- fixed bug in computing elements of orbits in orbital reduction
30
31Miscellaneous
32-------------
33
34- redefine isrelax to istight in cons_linear.c
35
36Build system
37------------
38
39### Cmake
40
41- A file cmake.log containing the changed options is written to the cmake build directory.
42- removed replacement of the settings of RelWithDebInfo
43- add compile option -ffp-contract=off or /fp:precise to enhance reproducibility across different systems
44
45### Makefile
46
47- add flags -ffp-contract=off and /fp:precise to enhance reproducibility across different systems
48
49Interface changes
50-----------------
51
52### New parameters
53
54- added parameter "propagating/symmetry/symtiming" to determine when symmetries are computed and handled
55
56### Changed parameters
57
58- Disabled "propagating/symmetry/addconsstiming" since it is not used anymore.
59- Disabled "propagating/symmetry/ofsymcomptiming" since it is not used anymore.
60
61@section RN900 SCIP 9.0.0
62*************************
63
64Features
65--------
66
67- added simplification of abs(x)^n to x^n when n is even (simplify rule POW12)
68- in expression simplification, added possibility to expand power of sum with exponents larger than 2 (simplify rule POW7)
69- in expression simplification, added possibility to expand products with sums as factor when there are more than two factors (simplify rule SP12b)
70- in expression simplification, added possibility to allow expanding power of products with fractional exponent (simplify rule POW5a)
71- can now build with Lapack (used for solving nonlinear problems) explicitly; if IPOPT is used, then Lapack is accessed through it;
72 an interface to Lapack is available in lapack_calls.h
73- added support for logical constraints in binary variables and basic logical operators (and, or, not, equal) to AMPL .nl reader
74- indicator constraints now use the same slack variable for the linear constraints if binary variables are used multiple times
75 for indicator constraints
76- new diving heuristic indicatordiving that focuses on indicator variables which control semicontinuous variables
77- updated statistics on NLP relaxation; information on convexity of NLP has been added
78- added new bandit method (EXP.3-IX) that is the new default of the ALNS heuristic
79- added dialog to display recognized permutation symmetries ("display symmetry")
80- The symmetry detection code has been completely restructured. Instead of completely encoding symmetry information in
81 prop_symmetry.c, there is a new callback for constraint handlers, which returns symmetry relevant information by
82 encoding a constraint as a node and edge colored graph. This way, also custom constraint handlers can provide
83 symmetry information.
84- added special presolving step for logicor and set covering/packing for constraints with two variables and one independent variable
85- increased the depth field of the tree structure from 16 to 30 bits and the max depth of the search tree from 65534 to 1073741822
86- added new cut selector plugin called cutsel_ensemble. Performs a superset of hybrid cutsel. Implements new filtering methods and scoring options.
87- added new branching rule based on Gomory mixed-integer cuts
88- added new branching score to the reliability pseudo-cost branching rule
89- added new cut selector plugin called cutsel_dynamic. Performs a superset of hybrid cutsel. Implements new filtering methods and scoring options.
90- added monoidal strengthening to intersection cut generation of nlhdlr_quadratic
91- extended heuristic dps to run after processing the node and to use strict limits for the reoptimization step
92- extended obbt propagator to handle variables of the linear constraints corresponding to indicator constraints
93- added new heuristic heur_scheduler that models the selection of LNS and diving heuristics as a multi-armed bandit problem
94- added nonlinear handler for signomial expressions: adds cuts based on a difference of convex functions representation
95- Delayed separators are now called if no other cuts have been found. Previously, such separators were only called near stalling or when the separation rounds limit was reached.
96- added a new separator sepa_lagromory to generate Lagromory cuts in a relax-and-cut framework, i.e., GMI cuts generated
97 at different bases that are explored in the process of solving the Lagrangian dual problem at a node. This separator
98 is OFF by default.
99- when parsing nonlinear constraints from CIP files, the * after the number in a term is now optional if followed by a variable,
100 i.e., instead of 3*<x>*<y>, now also 3<x>*<y> can be read, but 3<x><y> is not supported;
101 this allows to read some CIP files that were written with SCIP < 8
102- when running bliss, we now limit the number of actually created generators and not the ones considered by bliss
103
104Performance improvements
105------------------------
106
107- Variable conflict-based addition of Schreier-Sims cuts for symmetry handling in prop_symmetry.c does no longer use
108 an expensive explicit conflict graph construction.
109- Only run propagation of indicator constraints if relevant variables have changed.
110- Propagation of indicator constraints propagates maximal activity of linear constraint to upper bound of slack variable.
111- Added initialization of LP relaxation for SOC constraints.
112- Avoided some numerical issues when separating SOC constraints.
113- If differentation of convex expression fails in convex nlhdlr, then a perturbed point is tried.
114- Use sassy/bliss as default symmetry computation package.
115- No longer linearize indicator constraints in undercover heuristic by default.
116- Deactivate pre-root heuristic zeroobj in undercover heuristic.
117- Added new branching score tiebreaker for reliability pseudo-cost branching rule
118- Try nearest bound if zero solution value is out of bounds in heuristic trivial.
119
120Interface changes
121-----------------
122
123### New and changed callbacks
124
125- Added solution linearization callback for nonlinear handlers.
126 The nonlinear handler may use this callback to add tight cuts that use the given solution as reference point to the cutpool.
127 The callback is called if option constraints/nonlinear/linearizeheursol is enabled.
128- The callback for copying problem data SCIP_DECL_PROBCOPY() now has a parameter "original" indicating whether the original
129 or transformed problem should be copied. Similarly, SCIPprobCopy() in prob.h/c has such a parameter.
130- Added CONSGETPERMSYMGRAPH and CONSGETSIGNEDPERMSYMGRAPH callback for constraint handlers, which provides symmetry information about constraints to SCIP.
131
132### Deleted and changed API methods
133
134- SCIPtpiInitLock(), SCIPtpiDestroyLock(), SCIPtpiInitCondition(), SCIPtpiDestroyCondition() now take a double
135 pointer to SCIP_LOCK/SCIP_CONDITION, respectively.
136- Renamed SCIPtpiSumbitJob() to SCIPtpiSubmitJob().
137- SCIPcreateConsIndicatorLinCons(), SCIPcreateConsIndicatorGenericLinCons() do not allow binvar to be NULL anymore
138- Replaced SCIPnlrowSetCurvature() by SCIPsetNlRowCurvature().
139- SCIPsnprintf() now returns the required string length in case reallocation is necessary.
140- SCIPcomputeCoverUndercover() receives three more arguments which nonlinearities to cover
141- removed definition of SQRT
142- SCIPincludeObjConshdlr(), SCIPincludeConshdlr(), SCIPconshdlrCreate() receive two more arguments for the
143 conshdlr callbacks CONSGETPERMSYMGRAPH and CONSGETSIGNEDPERMSYMGRAPH
144- removed SYM_VARTYPE, SYM_OPTYPE, SYM_CONSTTYPE, SYM_RHSTYPE, SYM_MATRIXDATA
145- new parameter issigned for SCIPcomputeOrbitsSym()
146- new parameter symtype for SCIPcomputeComponentsSym()
147- new parameter symtype and permvardomaincenter for SCIPlexicographicReductionAddPermutation()
148- replaced parameters matrixdata and exprdata of SYMcomputeSymmetryGenerators() by graph
149
150### New API functions
151
152- new functions for interfacing with Lapack: SCIPlapackIsAvailable(), SCIPlapackIsAvailable(), SCIPlapackComputeEigenvalues(), and SCIPlapackSolveLinearEquations
153 These functions should be used instead of SCIPisIpoptAvailableIpopt(), SCIPcallLapackDsyevIpopt(), and
154 SCIPsolveLinearEquationsIpopt() in the context of computing eigenvalues or solving linear equations.
155 If IPOPT is available, the calls will be passed on to Ipopt's interface to Lapack.
156- SCIPmultiplyBySumExprSum(), SCIPpowerExprSum()
157- SCIPsetParam()
158- SCIPgetPrimalDualIntegral() returns the primal dual integral stored in the statistics
159- new functions SCIPcreateConsIndicatorLinConsPure() and SCIPcreateConsIndicatorGenericLinConsPure() that
160 create indicator constraints from a linear constraint without a slack variable
161- SCIPgetNLPNlRowsStat() to retrieve counts on linear, convex, and nonconvex rows in NLP
162- SCIPnlhdlrSetSollinearize(), SCIPnlhdlrHasSollinearize()
163- SCIPbendersGetNLPParam()
164- new API functions SCIPlexicographicReductionGetStatistics(), SCIPlexicographicReductionPrintStatistics(),
165 SCIPlexicographicReductionPropagate(), SCIPlexicographicReductionAddPermutation(), SCIPlexicographicReductionReset(),
166 SCIPlexicographicReductionFree(), SCIPincludeLexicographicReduction(), for lexicographic reduction.
167- new API functions SCIPorbitopalReductionGetStatistics(), SCIPorbitopalReductionPrintStatistics(),
168 SCIPorbitopalReductionPropagate(), SCIPorbitopalReductionAddOrbitope(), SCIPorbitopalReductionReset(),
169 SCIPorbitopalReductionFree(), SCIPincludeOrbitopalReduction(), SCIPorbitopalReductionGetDefaultColumnOrdering(),
170 for orbitopal fixing.
171- new API functions SCIPorbitalReductionGetStatistics(), SCIPorbitalReductionPrintStatistics(),
172 SCIPorbitalReductionPropagate(), SCIPorbitalReductionAddComponent(), SCIPorbitalReductionReset(),
173 SCIPorbitalReductionFree(), SCIPincludeOrbitalReduction(), for orbital fixing.
174- new API functions SCIPgetShadowTreeEventHandlerExecutionTime(), SCIPshadowTreeGetShadowNodeFromNodeNumber(),
175 SCIPshadowTreeGetShadowNode(), SCIPgetShadowTree(), SCIPactivateShadowTree(), SCIPincludeEventHdlrShadowTree(),
176 for managing a copy of the branch-and-bound tree for symmetry handling purposes.
177- SCIPdotWriteOpening(), SCIPdotWriteNode(), SCIPdotWriteArc(), SCIPdotWriteClosing()
178- SCIPincludeCutselEnsemble(), SCIPselectCutsEnsemble() to include cutsel_ensemble or use the selection algorithm
179- SCIPincludeBranchruleGomory() includes new gomory cut based branching rule
180- SCIPgetVarAvgGMIScore(), SCIPincVarGMISumScore(), SCIPgetVarLastGMIScore(), SCIPsetVarLastGMIScore() set historical values used by SCIP's default branching rule
181- SCIPincludeNlhdlrSignomial() includes the signomial nonlinear handler
182- SCIPgetExprMonomialData() returns a monomial representation of a product expression
183- SCIPestimateRoot() computes estimators for roots with exponent in [0,1]
184- SCIPincludeCutselDynamic(), SCIPselectCutsDynamic() to include cutsel_dynamic or use the selection algorithm
185- SCIPincludeSepaLagromory() to include the new Lagromory separator
186- SCIPconsCompCheck() to compare two constraints based on their check priority
187- SCIPgetConsPermsymGraph() and SCIPgetConsSignedPermsymGraph() to access the (signed) permutation symmetry detection graph of a constraint
188- SCIPsetConshdlrGetPermsymGraph() and SCIPsetConshdlrGetSignedPermsymGraph() to set the (signed) permutation symmetry detection graph of a constraint
189- SCIPconshdlrSupportsPermsymDetection() and SCIPconshdlrSupportsSignedPermsymDetection() to access whether a conshdlr supports detection of (signed) permutation symmetries
190- new API functions for creating and manipulating a symmetry detection graph: SCIPcreateSymgraph(), SCIPfreeSymgraph(), SCIPcopySymgraph(), SCIPextendPermsymDetectionGraphLinear(),
191 SCIPaddSymgraphVarAggregation(), SCIPaddSymgraphOpnode(), SCIPaddSymgraphValnode(), SCIPaddSymgraphConsnode(), SCIPgetSymgraphVarnodeidx(), SCIPgetSymgraphNegatedVarnodeidx(),
192 SCIPupdateSymgraphLhs(), SCIPupdateSymgraphRhs(), SCIPfixSymgraphVarnode(), SCIPaddSymgraphEdge(), SCIPcomputeSymgraphColors(), SCIPgetSymgraphSymtype(), SCIPgetSymgraphVars(),
193 SCIPgetSymgraphNVars(), SCIPgetSymgraphNConsnodes(), SCIPgetSymgraphNNodes(), SCIPgetSymgraphNEdges(), SCIPgetSymgraphEdgeFirst(), SCIPgetSymgraphEdgeSecond(),
194 SCIPgetSymgraphVarnodeColor(), SCIPgetSymgraphNodeType(), SCIPgetSymgraphNodeColor(), SCIPisSymgraphEdgeColored(), SCIPgetSymgraphEdgeColor(), SCIPgetSymgraphNVarcolors(),
195 SCIPhasGraphUniqueEdgetype(), SCIPallocateSymgraphConsnodeperm(), SCIPcreateSymgraphConsnodeperm(), SCIPgetSymgraphConsnodeperm(), SCIPfreeSymgraphConsnodeperm(),
196 SCIPgetSymActiveVariables(), SCIPfreeSymDataExpr(), SCIPgetSymExprdataNConstants(), SCIPgetSymExprdataConstants(), SCIPgetCoefSymData(),
197 SCIPcreateSymOpNodeType(), SCIPgetSymOpNodeType()
198- SCIPexprhdlrSetGetSymdata(), SCIPexprhdlrHasGetSymData(), SCIPgetSymDataExpr(), SCIPcallExprGetSymData() to access symmetry data of expressions
199- SYMcheckGraphsAreIdentical() to check whether two symmetry detection graphs are identical
200- new functions SYMbuildSassyGraph(), SYMbuildSassyGraphCheck()
201- new type SYM_GRAPH
202- new definitions SCIP_DECL_CONSGETPERMSYMGRAPH, SCIP_DECL_EXPRGETSYMDATA
203- new member SYM_NODETYPE_CONS in SYM_NODETYPE enum
204- new members SYM_CONSOPTYPE_SUM, SYM_CONSOPTYPE_SLACK, SYM_CONSOPTYPE_COEF, SYM_CONSOPTYPE_RHS, SYM_CONSOPTYPE_LAST in SYM_CONSOPTYPE enum
205- new defintion SCIP_DECL_EXPRGETSYMDATA
206- new function SCIPdetectSingleOrDoubleLexMatrices()
207
208### Command line interface
209
210- Added optional parameter -i when calling SCIP in AMPL-mode (-AMPL parameter).
211 If -i is specified, a SCIP shell is started where normally SCIPsolve() would be called.
212
213### Interfaces to external software
214
215- added interface to nauty/traces for symmetry computation
216- added interface to sassy, a preprocessor for symmetry computation
217- The directory src/sassy contains the source code of sassy.
218- Added interface to Lapack (used for solving nonlinear problems).
219- The AMPL interface now supports parameters specified in AMPL command scripts via option scip_options.
220 The value of scip_options is expected to be a sequence of parameter names and values, separated by a space, e.g.,
221 `option scip_options 'limits/time 10 display/verblevel 1';`.
222 String values should not be quoted and spaces in string values are not supported.
223- sassy can be used now as preprocessor for nauty/traces
224- The solution status codes written to AMPL solution files now match those from https://mp.ampl.com/details.html#_CPPv4N2mp3sol6StatusE.
225
226### Changed parameters
227
228- change default value of parameter separating/filtercutpoolrel to FALSE
229- Shrunk range of parameter "propagating/symmetry/sstleaderrule" from [0,3] to [0,2], removed "MAXCONFLICTS"-option.
230- Removed reading/gmsreader/freeints. A default upper bound of +inf is now assumed for integer variables in GAMS (which is the case since GAMS 23.1).
231- Disabled "propagating/symmetry/symfixnonbinaryvars" since it is not used in the new symmetry code.
232- Replaced "propagating/symmetry/onlybinarysymmetry" with "propagating/symmetry/enforcecomputesymmetry" and set to FALSE by default.
233- Disabled "propagating/symmetry/performpresolving" since running orbital reduction during presolving is not effective.
234- Repurposed "propagating/symmetry/usedynamicprop" since it now also applies to lexicographic reduction.
235- Changed default value of parameter "propagating/symmetry/addsymresacks" from FALSE to TRUE.
236
237### New parameters
238
239- separating/maxcutsgenfactor and separating/maxcutsrootgenfactor as factors (w.r.t. separating/maxcuts and
240 separating/maxcutsroot) for limits on the number of cuts generated (which used to be constants '2')
241- expr/pow/expandmaxexponent to specify limit on exponent when to expand power of sum
242- expr/pow/distribfracexponent to enable expanding power of products with fractional exponents
243- expr/product/expandalways to enable expanding any product with sums as factor (that is, also when more than two factors)
244- nlhdlr/convex/maxperturb to specify maximal perturbation of non-differential reference points
245- benders/default/nlpiterlimit to adjust iteration limit for NLP solver for Benders' decomposition NLP subproblems
246- limits/objectivestop to interrupt the solve as soon as a primal solution is found
247 that is at least as good as the given value
248- heuristics/undercover/{coverand,coverind,covernl} to control which nonlinearities to consider (by default only "and" and nonlinear constraints)
249- cutselection/ensemble/∗ all parameters for new ensemble cut selector
250- cutselection/dynamic/∗ all parameters for new dynamic cut selector
251- branching/relpscost/gmiavgeffweight specifies the weight in the relpscost branching score of the normalized efficacy of all generated GMI cuts (for a variable)
252 branching/relpscost/gmilasteffweight specifies the weight in the elpscost branching score of the normalized efficacy of the last generated GMI cut (for a variable)
253- nlhdlr/quadratic/usemonoidal to enable monoidal strengthening when separating quadratics with intersection cuts
254- nlhdlr/quadratic/trackmore to collect more statistics for monoidal strengthening when separating quadratics with intersection cuts
255- nlhdlr/quadratic/useminrep to use the minimal representation to compute cut coefficients when separating quadratics with intersection cuts
256- nlhdlr/quadratic/sparsifycuts to enable sparsification of intersection cuts for quadratics
257- heuristics/dps/reoptlimits to set strict limits for the reoptimization step in dps
258- heuristics/dps/timing to run dps after processing the node
259- heuristics/scheduler/∗ all parameters for new scheduler heuristic
260- nlhdlr/signomial/enabled, nlhdlr/signomial/maxnundervars, nlhdlr/signomial/mincutscale: parameters for the signomial nonlinear handler
261- separating/lagromory/freq to denote the frequency for calling Lagromory separator
262- separating/lagromory/away to denote the minimal integrality violation of a basis variable to try separation
263- separating/lagromory/dynamiccuts to denote whether the generated cuts be removed from LP if they are no longer tight
264- separating/lagromory/maxroundsroot to denote the maximal number of separation rounds in the root node
265- separating/lagromory/maxrounds to denote the maximal number of separation rounds in a non-root node
266- separating/lagromory/nmaxcutsperlproot to denote, in the root node, the maximal number of Lagromory cuts that can be
267 separated per explored basis of the Lagrangian dual
268- separating/lagromory/nmaxcutsperlp to denote, in a non-root node, the maximal number of Lagromory cuts that can be
269 separated per explored basis of the Lagrangian dual
270- separating/lagromory/perroundnmaxlpiters to denote the maximal number of separating LP iterations that are allowed per
271 separation round
272- separating/lagromory/dualdegeneracyratethreshold to denote the minimum dual degeneracy rate for the separator execution
273- separating/lagromory/varconsratiothreshold to denote the minimum variable-constraint ratio on the optimal face for the
274 separator execution
275- many other advanced parameters for the Lagromory separator, which are also mentioned under separating/lagromory/∗
276
277### Data structures
278
279- new data structure SYM_GRAPH to encode symmetry information from a constraint
280- new data structure SYM_EXPRDATA to encode symmetry information from expressions
281- replaced enum SYM_SYMTYPE by a complete new one; removed SYM_RHSSENSE, added SYM_NODETYPE and SYM_CONSOPTYPE
282
283Deleted files
284-------------
285
286- deleted the now unused files: tpi_none.h, tpi_openmp.h, tpi_tnycthrd.h, type_tpi_none.h, type_tpi_openmp.h, type_tpi_tnycthrd.h
287
288Unit tests
289----------
290
291- new unittests for nlhdlr_quadratic that test monoidal strengthening and the use of the minimal representation to compute cut coefficients
292- unittests for nlhdlr_signomial
293
294Testing
295-------
296
297- changed `set lim obj` to `set lim objective` in ctest since `obj` is no longer unambiguous
298
299Build system
300------------
301
302### Cmake
303
304- New flag -DLAPACK=on for linking with Lapack (must be available in the system)
305- added flag option "SYM=sbliss" for using sassy/bliss as a graph automorphism package
306- use SYM=sbliss by default, since sassy and bliss are now shipped with SCIP.
307- added flag option "SYM=snauty" for using sassy/nauty as a graph automorphism package
308
309### Makefile
310
311- added flag option "nauty" for SYM variable to specify which graph automorphism package should be used
312- added flag option "sbliss" (sassy/bliss) for SYM variable to specify which graph automorphism package should be used
313- added flag option "snauty" (sassy/nauty) for SYM variable to specify which graph automorphism package should be used
314- use SYM=sbliss by default, since sassy and bliss are now shipped with SCIP
315- New flag LAPACK for linking with Lapack (must be available in the system)
316- A file scip/config.h is created in the build directory ($(OBJDIR)/include) now.
317 Defining NO_CONFIG_HEADER is no longer necessary and has no effect anymore.
318
319Fixed bugs
320----------
321
322- Number of runs in which separation is enabled will now be correct as per "separating/maxruns" parameter. Earlier,
323 separation was enabled for "maxruns + 1" number of runs, i.e., separation was enabled even when "maxruns = 0" was set.
324- add safeguard for number of selected cuts
325- use double double precision for delta in activity updates of cons_linear.c
326- sort constraints in checkSolOrig() to keep the logic of constraint handlers intact
327- fixed make install when SHARED=no and make uninstall
328- check absolute coefficients relative to extremal average to avoid invalid unifications in normalizeCons()
329- enforce and check symmetry-based constraints to take their locks (in dual reductions) into account
330- flush changes at the end of SCIPlpiSetBase() in lpi_grb.c to apply the newly set basis correctly
331
332Miscellaneous
333-------------
334
335- The TPI has been changed to become mostly independent from the actual parallel interface during compile time.
336 For this, the locks and conditions are now pointers to abstract structs.
337- fixed that scip/def.h, the header for C preprocessor definition (#define's), included headers for some SCIP type and function definitions
338 (scip/type_retcode.h, scip/type_message.h, scip/pub_message.h)
339
340
341@page RN80 Release notes for SCIP 8.1
342
343@section RN805 SCIP 8.1.0
344*************************
345
346Fixed bugs
347----------
348
349- fixed that scaling of rows in Gurobi interface (SCIPlpiScaleRow()) changed infinite sides to large finite ones (1e20) when scale factor is negative
350- check whether objective limit is truly reached in SCIPlpiIsStable()
351- if an objective limit is set and Mosek claims that it is exceeded, check that this is indeed the case in SCIPlpiIsStable()
352- the .mps file reader was extended to additionally accept .mps files with the objective sense section on one line
353- ensure that delayed cutpool separation does not happen if enough cuts have been found already
354- fixed that a Gurobi or Mosek interface (LPI) could not be freed from a thread different than the one it was created in, which lead to problems when, e.g., using the concurrent optimizer
355- in cons_varbound if both variables are fixed, instead of propagating the constraint check the feasibility of the constraint since propagating can lead to unnecessary numerical troubles
356- fixed memory leak in branching rule "distribution"
357- fixed that undercover did not enforce that sufficiently many variables in an and-constraints were fixed to have it linearized in the generated sub-scip
358- fixed two bugs in cons_varbound: avoid adding variable bounds if vbdcoef is infinite and unlock/lock variables if lhs/rhs/vbdcoef are changed
359- globalize constraint changes before bound changes during the effective root shift in treeSwitchPath() to correctly update variable locks by avoiding global bounds with outstanding bound change events when deleting constraints
360- fixed error when attempting to copy SCIP with activated pricers
361- remove integrality check for implicit integral variables in cons_integral.c, updated the definition for variable type implicit integer to be more explicit that these variables can take fractional values, and updated FAQ entry
362- updated and, or, and pseudoboolean constraint handlers to better handle fractional implicit integer variables in enforcement
363- avoid invalid strong Chvatal-Gomory cuts by ceiling with tolerance in the calculation of parameter k and flooring slack coefficients with standard epsilon tolerance as well as quad precision
364- add missing row links to columns in SCIPflushRowExtensions() required to maintain correct row norms
365- restrict separator intobj to solutions for which there can be no better feasible integral objective values to avoid cutting them off
366- delay removal of clique lists from SCIPvarRemoveCliquesImplicsVbs() into cliqueCleanup() to avoid segmentation faults by incomplete cleanups after variable conversions
367- reject sub-solutions with invalid objectives in SCIPtranslateSubSols() due to contradicting infinite contributions
368- correct column index in getMinMaxActivityResiduals() to make presolver dualinfer work
369- copy quiet flag from main scip's message handler to the one of solverscip in concurrent optimization
370- avoid bound tightening cycles towards huge redundancy bounds in fullDualPresolve() to avert fatal numerical trouble in representing vertices of linear relaxations with unbounded domains
371- fix problem where debug solution did not work if branching constraints are present
372- update index of dominating variable on coefficient deletion in dualPresolving() of constraint handler logicor
373- pass on flags from a redundant to the implying varbound constraint in preprocessConstraintPairs() to avoid suboptimal fixings by model relaxations
374- apply reductions of dualinfer only if a dual solution exists (primal is bounded)
375- before presolving is finished check solutions before retransforming them including tiny values to keep check flags consistent
376- disable heuristics before and during presolving in benders decomposition to avoid messing up the objective structure in the solution store by dropping auxiliary variables in the required retransformations
377- correct local flag of singleton conflict constraints in tightenSingleVar() against invalid bound globalization
378- respect unboundedness in the computation of activity bounds in conflict.c to avoid invalid huge bounds due to small coefficients on unbounded variables
379- ensure positive sides of a linear constraint when recognizing a set partition in rangedRowSimplify() to account for redundancy issues
380- relax numerical conditions for variable aggregations to avert invalid variable fixings
381- fixed harmless read of uninitialized data when creating parameters
382- fix call of SCIPnlpiOraclePrintProblem in nlpi_worhp
383
384Performance improvements
385------------------------
386
387- Use sassy/bliss as default symmetry computation package.
388
389Interface changes
390-----------------
391
392### Interfaces to external software
393
394- added interface to nauty/traces for symmetry computation
395- added interface to sassy, a preprocessor for symmetry computation
396- The directory src/sassy contains the source code of sassy.
397
398Build system
399------------
400
401### Cmake
402
403- added flag option "SYM=sbliss" for using sassy/bliss as a graph automorphism package
404
405### Makefile
406
407- added flag option "nauty" for SYM variable to specify which graph automorphism package should be used
408- added flag option "sbliss" for SYM variable to specify which graph automorphism package should be used
409- use SYM=sbliss by default, since sassy and bliss are now shipped with SCIP
410
411Miscellaneous
412-------------
413
414- the parameter change callback is no longer called at the moment a parameter is created
415
416@page RN80 Release notes for SCIP 8.0
417
418@section RN804 SCIP 8.0.4
419*************************
420
421Features
422--------
423
424- use quad precision in cutsSubstituteMIR() for substituting slack variables into CMIR cuts
425- use quad precision for activity computations in cons_linear.c
426
427### Deleted and changed API methods
428
429- SCIPshrinkDisjunctiveVarSet() no longer attempts to cutoff the current node if it finds the
430 given disjunction to be infeasible; it is now in the responsibility of the caller to act accordingly
431
432### New API functions
433
434- added SCIPskipSpace
435- added XML parser routines from src/xml/xml.h
436
437### Interfaces to external software
438
439- updated XPRESS interface to work with XPRESS 41 as well
440- new interface to LP solver HiGHS (lpi_highs.cpp)
441
442### Changed parameters
443
444- changed integer parameter "propagating/symmetry/recomputrestart" from range {0, 1, 2} to being fixed at value 0
445
446Unit tests
447----------
448
449- added new checks for objective, bounds and sides inside the scaling tests in lpi/change.c
450
451Fixed bugs
452----------
453
454- relax condition of assert in lpSolve to hold only if lp/checkstability is true
455- OPB reader: dynamically increase the size of the line buffer for reading in getMaxAndConsDim()
456- Enabled the solution limit checks in SCIPsolveIsStopped in solve.c when in SCIP_STAGE_PRESOLVING
457- fix quad precision comparison for the calculation of knapsackcover constraints.
458- force copying of symmetry constraints for concurrent solve
459- increase the precision of double multiplications in quad precision environments
460- corrected handling of different variable types in symmetry
461- orbitope detection: refine computation of overlap structure and fixed bug in finding orbitope generators
462- ensure that winner is always determined in concurrent mode
463- when a row with invalid index range is added to the global cutpool, update the indices instead of failing with an assert
464- update of watched literals in cons_xor.c and ensure that fixed variables are counted in propacateCons()
465- avoid some numerical issue in check for redundant variables in linear constraints (introduced with version 8.0.2)
466- more rows are treated as being integral in cutsSubstituteMIR() for CMIR cuts
467- fixed several relaxations of the rhs of cuts to 0 in cuts.c
468- avoid aggregation into a single linear constraint if they should not be upgraded (needed for indicator constraints)
469- apply effective root changes before fork is repropagated during treeSwitchPath() in tree.c
470- avoid invalid objective value for solutions generated from an unbounded LP relaxation in case of a nonlinear objective function
471- disable recomputing symmetries after a restart (constraint removal is not permitted)
472- avoid cutting off optimal solutions for small feasibility tolerances in conflict analysis
473- initialize variable in presol_dualsparsify.c
474- fix in presolving of variable bound constraints to use absolute instead of relative difference
475- free variable histories in reoptimization mode
476- handle whitespaces in interactive shell history consistently
477- check and enforce equalities on which the objective is projected in cons_linear.c
478- ensure row feasibilities of solution shiftings in heur_oneopt.c and heur_twoopt.c
479- remove rounded row check blocking tolerable primal solutions in cons_varbound.c
480- fixed that presolve of logicor-constraints may have attempted to cutoff a root of the not yet existing branch-and-bound tree
481- only consider positive slack variables as active in benders.c
482- in the feasibility check of and/or constraints, allow for fractional values in operands
483- fixed linear outer-approximation for some composite absolute-value expressions
484
485Miscellaneous
486-------------
487
488- Extended documentation of the parameter limits/solutions to point out that the limit is first checked in presolving
489- Added more information about using SCIPcache- and SCIPflushRowExtensions() to documentation and comments
490- Extended the `how to add' sections of the documentation by adding information on how to include default plugins into SCIP
491
492@section RN803 SCIP 8.0.3
493*************************
494
495Examples and applications
496-------------------------
497
498- Externalize STP and PolySCIP applications
499
500Interface changes
501-----------------
502
503### Command line interface
504
505- When running the AMPL interface, the .nl filename extension does not need to be omitted for the input file anymore.
506
507Build system
508------------
509
510### Cmake
511
512- Forbid CMAKE_BUILD_TYPE nonstandard values
513- Move -I/path/to/src/amplmp/include to front of compiler flags for include directories
514
515### Makefile
516
517Fixed bugs
518----------
519
520- fixed an incorrect handling of xor constraints
521- the feasibility checker for integrality constraints now uses checkintegrality even for implied integers
522- skip integrality check in cons_integral for relaxation-only implicit-integer variables
523- fixed an issue caused by aggregated variables not added to a hashmap in the xor constraint handler
524- changed function solveRowEchelonGF2 in cons_xor.c to avoid errors if rank is 0
525- fixed that the implication presolver tried to aggregate or tighten bounds of multiaggregated variables
526- fixed a sign check in detection of linear constraints that are parallel to the objective
527- fixed bug in Clp and lpi_clp with missing basis information when calling the barrier with crossover; needs new Clp version
528- do not assume aggregation is successful in cons_setppc.c
529
530Miscellaneous
531-------------
532
533- Changed license to Apache 2.0, see https://www.apache.org/licenses/LICENSE-2.0.
534- When an LP could not be solved accurately, scaling is now turned off as a last fall-back method.
535- Methods for using the debug solution mechanism SCIPdebugAddSolVal, SCIPdebugGetSol, SCIPdebugGetSolVal,
536 SCIPdebugSolIsValidInSubtree, SCIPdebugIsMainscip, SCIPdebugSolEnable, SCIPdebugSolDisable, SCIPdebugSolIsEnabled,
537 SCIPwithDebugSol are now exported
538
539@section RN802 SCIP 8.0.2
540*************************
541
542Interface changes
543-----------------
544
545### Deleted and changed API methods
546
547- added input parameter SCIP_Bool initiallp to SCIPcutselsSelect
548- changed function type int to SCIP_Longint for SCIPcutpoolGetMaxNCuts
549- replaced SCIPsepastoreGetNCutsFound with SCIPsepastoreGetNCutsAdded following the naming convention for the new statistics
550- replaced SCIPsepaIncNAppliedCuts with SCIPsepaIncNCutsApplied
551
552### New API functions
553
554- added SCIPsepastoreGetNCutsAdded, SCIPsepastoreGetNCutsAddedViaPool, SCIPsepastoreGetNCutsAddedDirect
555- added SCIPsepaIncNCutsAdded, SCIPsepaDecNCutsAdded, SCIPsepaIncNCutsApplied, SCIPsepaGetNRootCalls, SCIPsepaGetNCutsAdded, SCIPsepaGetNCutsAddedViaPool, SCIPsepaGetNCutsAddedDirect, SCIPsepaGetNCutsAppliedViaPool, SCIPsepaGetNCutsAppliedDirect
556- added SCIPcutpoolGetNRootCalls, SCIPcutpoolGetNCutsAdded, SCIPcutpoolAddMaxNCuts, SCIPcutpoolSetTime, SCIPcutpoolAddNCalls, SCIPcutpoolAddNRootCalls, SCIPcutpoolAddNCutsFound, SCIPcutpoolAddNCutsAdded,
557- added SCIPcutselGetNCalls, SCIPcutselGetNRootCalls, SCIPcutselGetNRootCuts, SCIPcutselGetNRootForcedCuts, SCIPcutselGetNRootCutsFiltered, SCIPcutselGetNLocalCuts, SCIPcutselGetNLocalForcedCuts, SCIPcutselGetNLocalCutsFiltered,
558
559### Interfaces to external software
560
561- Added compatibility with Mosek 10.0.18.
562
563### New parameters
564
565- new parameters to turn on more statistics: misc/showdivingstats (diving heuristics), heuristics/alns/shownbstats (ALNS), estimation/showstats (tree size estimation)
566
567### Data structures
568
569- added nrootcalls and ncutsadded to SCIP_Cutpool
570- added fromcutpool flag to SCIP_Row and fixed 33 bit allocation
571- added ncalls, nrootcalls, nrootcutsselected, nrootcutsforced, nrootcutsfiltered, nlocalcutsselected, nlocalcutsforced, nlocalcutsfiltered to SCIP_Cutsel
572- added ncutsadded, ncutsaddedviapool, ncutsaddeddirect, ncutsappliedviapool, ncutsapplieddirect, nrootcalls to SCIP_Sepa
573- added ncutsadded, ncutsaddedviapool, ncutsaddeddirect to SCIP_Sepastore
574- fixed statistics of relaxators w.r.t. number of times conss/cuts were added
575
576Build system
577------------
578
579### Cmake
580
581- new option `-DAUTOBUILD` that configures scip with dependencies on availability.
582 Packages like Ipopt, PaPILO, Readline, Zimpl, ZLIB, GMP, Worhp are automatically found and linked, otherwise ignored.
583 The individual flags for these packages are ignored. This makes a quick build easier. It is by default set to off.
584
585Fixed bugs
586----------
587
588- read objective offset from ZIMPL files
589- Make sure that objective limit is disabled if not all variables are in the LP. If we would run into
590 an objective limit in this case, the results of the LP solver are unclear.
591- fixed bug in reopt.c, which occured for bounds outside of current valid bounds
592- fixed problem with recomputing symmetries after a restart
593- fixed bug in SCIPcalcMIR() with wrong order of arguments for removeZerosQuad()
594- fixed segmentation fault in update of cut statistic
595- fixed bug in presolving of and constraints by merging variables with multiple occurrences before cliquePresolve()
596- fixed bug in dual presolving of linear constraints by setting implicit integers to integers in multi-aggregation
597- fixed update of presolve statistics on added constraints and changed coefficients in constraint handler for nonlinear constraints
598- fixed bug with reading CIP files with large constraints split over several lines
599- fixed bug with infinite bounds in the computation of conflict cuts
600- fixed check for unbounded solution constructed by SCIPlpGetUnboundedSol(): The constructed solution is very likely infeasible
601 since scaling increases small numerical feasibility violations. Therefore, the solution is now always accepted. However, the
602 feasibility of the ray is now checked. This fix now might lead to several rounds of separation in order to resolve unbounded solutions,
603 whereas previously SCIP started to branch immediately.
604- changed to absolute tolerances in all redundancy checks for linear constraints
605
606Miscellaneous
607-------------
608
609- Added extended cutselector statistics splitting between root node specific and general statistics
610- Added extended and refined cutpool statistics showing the number of cuts added from the cutpool to the sepastore
611- Added extended and refined separator statistics to get a better view of the individual generators performance
612- turned off output of statistics for the following information by default:
613 diving heuristics, ALNS neighborhood information and tree size estimation statistics;
614 they can be turned on using the following new parameters:
615 misc/showdivingstats (diving heuristics), heuristics/alns/shownbstats (ALNS), estimation/showstats (tree size estimation)
616
617@section RN801 SCIP 8.0.1
618*************************
619
620Features
621--------
622
623- clique lifting in cons_setppc (parameter enablecliquelifting) is only disabled if it has been applied
624- avoid warning if Mosek has reached/exceeded the objective limit
625- improved curvature check for quadratic expressions when extended formulations are disabled
626
627Examples and applications
628-------------------------
629
630- Fixed handling of enforcing in the TSP example.
631
632Interface changes
633-----------------
634
635### Interfaces to external software
636
637- Added compatibility with Mosek 10.0.13.
638
639Build system
640------------
641
642- BLISS is now built from the vendored version from https://github.com/ds4dm/Bliss
643
644### Cmake
645
646- avoid warnings about unrecognized compiler warning silencing options when compilation with GCC fails
647- adjust mosek find module to version 9.3
648- added cmake compatibility for ipopt versions 3.14.x
649
650### Makefile
651
652- avoid warnings about unrecognized compiler warning silencing options when compilation with GCC fails
653- fixed that compilation with MS/Intel compilers on Windows and Cray compilers was broken when enabling PAPILO
654
655Fixed bugs
656----------
657
658- fixed uninitialized array in detection of suborbitopes
659- Fixed problem with reading long lines in LP/FZN/OPB/Diff-files. The buffer is now reallocated,
660 which also should be much faster.
661- fixed that recursive products in expressions were sometimes not flattened
662- fixed that expressions in original variables could not be simplified
663- fixed handling of objective limit with Mosek
664- made SCIPlpiGetSolverName()/SCIPlpiGetSolverDesc() thread-safe for LP Solvers (Cplex,Gurobi,Glop,Mosek,SoPlex,Xpress)
665- made SYMsymmetryGetName() thread-safe for Bliss
666- fixed memory allocation issue in detection of SOC nlhdlr
667- fixed that reaching the walltime limit in Ipopt was not handled properly
668- Deactivated dual fixing of unlocked variables with zero objective in presol_milp that SCIP is unable to postsolve.
669- set the column flag kImplInt for implicit integers in the papilo problem
670- fixed bug in propagation of indicator constraints (one case always reported a change through propagation)
671
672@section RN800 SCIP 8.0.0
673*************************
674
675Features
676--------
677
678- Variables that were marked as relaxation-only and that were not used in any solution (SCIP_SOL)
679 are now deleted when during a restart.
680- New symmetry handling method, symmetry handling inequalities based on the Schreier Sims table,
681 which is able to handle symmetries of arbitrary kinds of variables.
682- Revise way in which external memory (e.g., of LP-solver) is estimated.
683- The symmetry code can now heuristically search for orbitopes that do not completely handle
684 a symmetry component and add certain Schreier Sims cuts to such components.
685- The LPIs for Gurobi and Mosek are thread-safe now.
686- The complete code is now thread-safe by default.
687- New separator to generate mixing cuts (works well for stochastic programming with probabilistic constraint).
688- New parsing routines for cons_orbisack and cons_symresack.
689- Variables can now be marked to forbid aggregation.
690- Heuristic PADM can now reoptimize found solution with original objective function.
691- Added code to support debugging of catching or releasing of variables to var.c (prints backtrace
692 when catching and releasing).
693- SCIPintervalSin() and SCIPintervalCos() are now rounding-safe.
694- Removed special handling of second-order cones in undercover heuristic for now.
695- Removed use of Hessian sparsity pattern for nonquadratic nonlinear constraints in undercover heuristic.
696- Added reader for AMPL .nl files.
697- New separator sepa_rlt to compute cuts via the reformulation-linearization technique (RLT).
698- New separator sepa_minor to compute cuts from 2x2 minors of a violated semidefiniteness constraint that is
699 implied by the extended formulation for bilinear products.
700- New separator sepa_interminor to compute intersection cuts from 2x2 (not only principle) minors of a violated
701 rank-one constraint that is implied by the extended formulation for bilinear products.
702- Symmetry handling has been extended to detect also symmetries between variables that also appear in nonlinear constraints.
703- Improved OBBT propagator by only considering variables that are contained in at least one nonconvex expression that has an auxiliary variable.
704- Default parameter settings for NLP solves are now defined independently of the NLP solver.
705- Added table to print statistics on NLP solvers.
706- Knapsack, linear, logicor, setppc, and varbound constraints now add themselves to the NLP relaxation, if enabled.
707 And, linking constraints and bounddisjunctions in one variable are added to the NLP relaxation now.
708- Ipopt interface now supports warmstarts from a full primal/dual solution pair.
709- Extended data structure SCIP_ROWPREP and routines to assemble a linear inequality before it is turned into a SCIP row and
710 made it available via the API.
711- MIR procedure is now available for strengthening the Benders' optimality cut
712- SCIPbranchcandCalcLPCands() now also returns fractional variables in unbounded solutions.
713- New emphasis "benchmark" to avoid different solving paths that may come from checking remaining memory.
714- New plugin type for cut selection: users can now include their own cut selection rules, default rule moved to cutsel_hybrid.
715- New construction heuristic DPS which additionally needs a user-provided decomposition and splits the problem into several sub-SCIPs
716 according to this decomposition. The sub-SCIPs are solved and updated repeatedly until a feasible solution of the original problem is found.
717
718Expressions:
719- Removed support for expression types min and max for now. Removed support for expression type sign.
720 Removed complex expression types sum, product, linear, quadratic, polynomial.
721 Removed support for parameterized expressions.
722- Added support for expression types sin, cos, and entropy. Added an expression type that stores a SCIP variable.
723- Added handling of sin and cos expressions in OSiL reader.
724- Added handling of sin, cos, and tan expressions in ZIMPL reader.
725- Added expression handler plugin type, removed user expression type.
726- Replaced expressions, expression trees, and expression graphs by a new implementation of expressions.
727- Added differentiation methods (Gradients and Hessian directions) to expressions.
728- Added integrality information to expressions.
729- Added comparison and hashing of expressions.
730- Improved simplification of expressions and identification of common subexpressions, in particular terms that appear
731 equally in several quadratic functions are now identified.
732- Expression simplification now expands powers also when the resulting exponents will be larger than 2.
733- Added table to print statistics on expression handlers.
734- Removed interval-arithmetic evaluation from expression interpreter (interfaces to automatic differentiation codes).
735- Hessians for user-provided expression handlers are not available in the NLP solver interfaces for now.
736- Sparse Hessians are now returned by expression interpreter. Removed dense Hessians.
737
738Constraint handlers for NLP:
739- cons_nonlinear has been completely rewritten and now handles constraints of the form lhs <= expr <= rhs, where
740 expr is an expression using the new expression type. A linear part of a nonlinear constraint is no longer distinguished.
741- Methods that work on a particular nonlinear structure are now implemented via nonlinear handlers (nlhdlr).
742 These handlers are plugins of cons_nonlinear and interact with cons_nonlinear by detecting structures in expressions and
743 providing propagation and separation mechanisms.
744- Added nlhdlr "default" as a mandatory nlhdlr: this is a nlhdlr that gets active on expressions that no other nlhdlr handles.
745 It then uses the callbacks implemented in expression handlers to provide domain propagation and linear under/overestimates.
746- Added nlhdlr for quadratic expressions: domain propagation that was previously part of cons_quadratic; separation via intersection cuts (currently disabled).
747- Added nlhdlr for bilinear expressions: collects bilinear products and provides under/overestimation of a product over a 2D-projection of the LP.
748- Added nlhdlr for convex and concave expressions: detection of convex/concave subexpressions and linear under/overestimation.
749- Added nlhdlr for quotients: detects quotients, provides specialized linear under/overestimation and domain propagation for univariate quotients.
750- Added nlhdlr for perspective reformulations: detects expressions in semi-continuous variables and tightens linear
751 under/overestimates of these expressions by applying a perspective transformation.
752- Added nlhdlr for second-order cones: detects second-order cone constraints (as ||x|| <= t or a quadratic that can written like that) and
753 separates on a disaggregated reformulation (similar to cons_soc previously).
754- Removed constraint handlers abspower, bivariate, quadratic, and soc.
755- Removed simplification of duplicate abspower constraints for now.
756 Removed simplification of abspower constraints with loose variables.
757 Removed resolving of domain propagation (ConsResProp callback) and conflict analysis for abspower constraints.
758 Removed propagation of varbounds for variables of abspower constraints.
759 Removed reformulation of abs(x)^p * x into signpower expression for now.
760- Removed reformulation of SOC constraints when adding to the NLP.
761 Removed possibility to add linearizations a la Glineur or BenTal&Nemirovski for SOC constraints.
762- Removed possibility to disaggregate quadratic constraints.
763 Removed lifted tangent inequalities for bilinear terms in quadratic constraints.
764 Removed option to project LP solution onto feasible region of a quadratic constraint via interior point or gauge function.
765 Removed handling of unbounded LPs when enforcing quadratic constraints.
766- Removed construction of cuts from interval gradients for nonlinear constraints.
767 Removed possibility to pretend that all nonlinear constraints are convex.
768 Removed possibility to create local or non-initial nonlinear constraints for now.
769- Removed explicit reformulation of nonlinear constraints in presolve.
770 An extended formulation is now generated implicitly and used to construct the LP relaxation,
771 but the original formulation is used to check feasibility, propagate variable domains, etc.
772 Variables that are added for the extended formulation are now marked as relaxation-only.
773- Improved locking of nonlinear variables in nonlinear constraints by taking monotonicity into account.
774- Improved mechanisms to detect and handle structures in nonlinear constraints, which allows for several algorithms
775 to work simultaneously on equal or overlapping expressions.
776- Improved linearization of (sums of) products of binary variables, e.g., clique information is now taken into account.
777 Removed option to linearize products between a binary and a non-binary variable.
778- Nonlinear constraints with the same function (but possibly different left- or right-hand-side) are now merged.
779- When a variable appears in only one concave less-or-equal constraint, it will be fixed to one of its bounds in more cases now.
780- New branching rule for variables in nonlinear constraints (implemented in cons_nonlinear) that scores candidates
781 based on constraint violation, variable type, and pseudo-costs simultaneously.
782- Added tables to print statistics of nonlinear constraint handler and nonlinear handlers.
783
784Performance improvements
785------------------------
786
787- Use the objective cutoff row as base row for separation in sepa_aggregation.c.
788- Separate lifted cover cuts based on newer lifting function of Letchford and Souli (2019) in sepa_aggregation.c.
789- In-tree restarts due to tree size estimation have been made compatible with orbital fixing.
790- Improved upgrade of orbisacks to packing/partitioning orbitopes.
791- Improved running time of symresack cover separation.
792- Improved propagation algorithm for orbisack and symresack.
793- Improved handling for expressions of type signpower in CppAD interface by making use of CppADs conditional expressions.
794- Faster reevaluation of Hessian for quadratic expressions in CppAD interface.
795- Enabled optimization of taped expressions in the CppAD interface.
796- Sparse Hessian evaluation for expressions with sparse Hessian in the CppAD interface.
797- Disabled branching on variables that are added for the extended formulation of a nonlinear constraint.
798- Prefer branching on variables in nonconvex terms of nonlinear constraints also if a cut could be generated but would yield a small reduction in the convexification gap only.
799- When violations of nonlinear constraints are tiny, the feasibility tolerance for the LP relaxation may now be reduced temporarily to allow for cuts to have an effect.
800- Improved under/overestimation of multidimensional vertex-polyhedral (e.g., multilinear or concave) functions by use of scaling and keeping the cut-generating LP around.
801- Products in nonlinear constraints are no longer disaggregated for the extended formulation.
802- No longer relax bounds of integral variables when computing bounds on activity in nonlinear constraints.
803- Revised and improved Ipopt interface.
804- Revised and improved subNLP primal heuristic, in particular choice of iteration limit and starting condition and reuse of subSCIP.
805- Merge strongcg into the gomory separator to avoid computing the same base equality twice. The files
806 sepa_strongcg.{h|c} have been removed.
807- The RENS neighborhood in ALNS now fixes fractional variables if necessary for reaching its target fixing rate.
808- Use cpsolver emphasis in sepa_rapidlearning.
809- If decomposition/maxgraphedge = 0, the computation of the block graph is completely turned off.
810- Fixed a performance bug in cons_integral.c where rounding information was passed incorrectly to the generic diving algorithm.
811
812Examples and applications
813-------------------------
814
815- Add c++ Sudoku example
816- Removed circle.c and renamed string.c to spring.c in CallableLibrary example.
817- SCIP-Jack (Steiner tree application):
818 Most files have been modified and many new ones have been added (code base more than doubled).
819 Two new problem classes are supported: maximum-weight connected subgraph problem with budget constraints, partial-terminal node-weighted Steiner tree problem.
820 Major performance improvements accross all problem classes that are supported.
821
822Interface changes
823-----------------
824
825### New and changed callbacks
826
827- extend SEPAEXEC{LP,SOL} callbacks by parameter "depth", which should be used within separation instead of SCIPgetCurrentDepth()
828- extend SCIPseparateSolCutpool() by parameter "pretendroot", which is passed to SCIPcutpoolSeparate() instead of SCIPtreeGetCurrentDepth(scip->tree) == 0
829- removed SCIP_DECL_EXPRGRAPHVARADDED, SCIP_DECL_EXPRGRAPHVARREMOVE, SCIP_DECL_EXPRGRAPHVARCHGIDX
830- removed SCIP_DECL_USEREXPRESTIMATE, SCIP_DECL_USEREXPREVAL, SCIP_DECL_USEREXPRINTEVAL, SCIP_DECL_USEREXPRCURV, SCIP_DECL_USEREXPRPROP, SCIP_DECL_USEREXPRCOPYDATA, SCIP_DECL_USEREXPRFREEDATA, SCIP_DECL_USEREXPRPRINT
831- added SCIP_DECL_EXPR_OWNERFREE, SCIP_DECL_EXPR_OWNERPRINT, SCIP_DECL_EXPR_OWNEREVALACTIVITY, SCIP_DECL_EXPR_OWNERCREATE
832- added SCIP_DECL_EXPR_INTEVALVAR, SCIP_DECL_EXPR_MAPEXPR
833- added SCIP_DECL_EXPRCOPYHDLR, SCIP_DECL_EXPRFREEHDLR, SCIP_DECL_EXPRCOPYDATA, SCIP_DECL_EXPRFREEDATA, SCIP_DECL_EXPRPRINT, SCIP_DECL_EXPRPARSE, SCIP_DECL_EXPRCURVATURE, SCIP_DECL_EXPRMONOTONICITY, SCIP_DECL_EXPRINTEGRALITY, SCIP_DECL_EXPRHASH, SCIP_DECL_EXPRCOMPARE, SCIP_DECL_EXPREVAL, SCIP_DECL_EXPRBWDIFF, SCIP_DECL_EXPRFWDIFF, SCIP_DECL_EXPRBWFWDIFF, SCIP_DECL_EXPRINTEVAL, SCIP_DECL_EXPRESTIMATE, SCIP_DECL_EXPRINITESTIMATES, SCIP_DECL_EXPRSIMPLIFY, SCIP_DECL_EXPRREVERSEPROP
834- removed SCIP_DECL_QUADCONSUPGD
835- added SCIP_DECL_VERTEXPOLYFUN
836- added argument nvarexprs to SCIP_DECL_NONLINCONSUPGD to inform upgrade method about number of variables in constraint
837- removed SCIP_DECL_EXPRGRAPHNODEREFORM
838- added SCIP_DECL_NLHDLRCOPYHDLR, SCIP_DECL_NLHDLRFREEHDLRDATA, SCIP_DECL_NLHDLRFREEEXPRDATA, SCIP_DECL_NLHDLRINIT, SCIP_DECL_NLHDLREXIT, SCIP_DECL_NLHDLRDETECT, SCIP_DECL_NLHDLREVALAUX, SCIP_DECL_NLHDLRINTEVAL, SCIP_DECL_NLHDLRREVERSEPROP, SCIP_DECL_NLHDLRINITSEPA, SCIP_DECL_NLHDLREXITSEPA, SCIP_DECL_NLHDLRENFO, SCIP_DECL_NLHDLRESTIMATE
839- replaced BMS_BLKMEM* blkmem argument of SCIP_DECL_NLPICOPY by SCIP* scip, removed targetnlpi argument
840- added SCIP* scip and SCIP_NLPIDATA** nlpidata arguments to SCIP_DECL_NLPIFREE
841- added SCIP* scip to SCIP_DECL_NLPIGETSOLVERPOINTER, SCIP_DECL_NLPICREATEPROBLEM, SCIP_DECL_NLPIFREEPROBLEM, SCIP_DECL_NLPIGETPROBLEMPOINTER, SCIP_DECL_NLPIADDVARS, SCIP_DECL_NLPIADDCONSTRAINTS, SCIP_DECL_NLPISETOBJECTIVE, SCIP_DECL_NLPICHGVARBOUNDS, SCIP_DECL_NLPICHGCONSSIDES, SCIP_DECL_NLPIDELVARSET, SCIP_DECL_NLPIDELCONSSET, SCIP_DECL_NLPICHGLINEARCOEFS, SCIP_DECL_NLPICHGOBJCONSTANT, SCIP_DECL_NLPISETINITIALGUESS, SCIP_DECL_NLPISOLVE, SCIP_DECL_NLPIGETSOLSTAT, SCIP_DECL_NLPIGETTERMSTAT, SCIP_DECL_NLPIGETSOLUTION, SCIP_DECL_NLPIGETSTATISTICS
842- replaced SCIP_DECL_NLPICHGEXPRTREE by SCIP_DECL_NLPICHGEXPR
843- removed nquadelems, quadelems, exprvaridxs arguments from SCIP_DECL_NLPIADDCONSTRAINTS, changed exprtrees argument to exprs
844- removed nquadelems, quadelems, exprvaridxs arguments from SCIP_DECL_NLPISETOBJECTIVE, changed exprtree argument to expr
845- removed SCIP_DECL_NLPICHGQUADCOEFS, SCIP_DECL_NLPICHGNONLINCOEF, SCIP_DECL_NLPISETMESSAGEHDLR
846- added SCIP_NLPIPROBLEM* problem to SCIP_DECL_NLPIGETSOLVERPOINTER
847
848### Deleted and changed API methods
849
850- When calling SCIPdelVar() in the SCIP_STAGE_PROBLEM stage, it is now documented as the user's responsibility to ensure
851 the variable is not present in any constraints. Otherwise, SCIPsolve() now returns SCIP_INVALIDDATA.
852- removed SCIPselectCuts(), replaced by SCIPselectCutsHybrid() of the hybrid cut selector plugin
853- If SCIPvarMarkRelaxationOnly() is called for a variable, then this now need to happen before the
854 variable is added to the transformed problem (SCIPaddVar()).
855 SCIPvarMarkRelaxationOnly() will automatically call SCIPvarMarkDeletable().
856- SCIPcomputeOrbitsFilterSym() and SCIPcomputeComponentsSym(): Type of argument componentblocked
857 changed from SCIP_Shortbool* to unsigned*.
858- removed SCIPsetParam()
859- SCIPcreateConsOrbitope() and SCIPcreateConsBasicOrbitope() have two new arguments "usedynamicprop"
860 and "mayinteract" to encode whether a dynamic reordering of the orbitope rows shall be used in
861 full orbitope propagation and whether the orbitope might interact with other symmetry handling
862 methods, respectively.
863- internal function SCIPgetPropertiesPerm() has been replaced by SCIPisInvolutionPerm()
864- internal function SCIPgenerateOrbitopeVarsMatrix() has new arguments "storelexorder", "lexorder",
865 "nvarsorder", "maxnvarsorder" to compute and store the lexicographic order defined by an orbitope
866- renamed SCIPcomputeArraysIntersection() and SCIPcomputeArraysSetminus() to
867 SCIPcomputeArraysIntersectionInt() and SCIPcomputeArraysSetminusInt(), respectively, and changed
868 their return type from SCIP_RETCODE (which _always_ was SCIP_OKAY) to void
869- removed SCIPincludeDialogDefault(), use SCIPincludeDialogDefaultBasic() instead and check whether you also need SCIPincludeDialogDefaultSet() and SCIPincludeDialogDefaultFix()
870- removed exprint argument from SCIPaddNlRowGradientBenderscutOpt()
871- added copyexprhdlrs argument to SCIPcopyPlugins() (19th position)
872- added copycutselectors argument to SCIPcopyPlugins() (10th position)
873- removed refpoint argument from SCIPaddSquareSecant()
874- added argument exprdata to SYMcomputeSymmetryGenerators()
875- removed SCIPconsNonlinearGetRhs(), SCIPconsNonlinearGetLhs(), SCIPconsNonlinearAddLinearCoef()
876- removed arguments timelimit, minimprove, itercontingent, and iterused from SCIPapplyHeurSubNlp()
877- removed SCIPresolveSolHeurSubNlp(), SCIPgetSubScipHeurSubNlp(), SCIPgetVarMappingScip2SubScipHeurSubNlp(), SCIPgetVarMappingSubScip2ScipHeurSubNlp()
878- SCIPlockVarCons() and SCIPunlockVarCons() are now allowed in stage TRANSFORMED as well
879- Added functions SCIPsetSepaIsParentsepa(), SCIPsetSepaParentsepa() [in scip_sepa.h], SCIPsepaSetIsParentsepa(), SCIPsepaSetParentsepa() [in sepa.h],
880 SCIPsepaIsParentsepa(), SCIPsepaGetParentsepa() [in pub_sepa.h]
881- Added function SCIPpruneTree() to immediately delete nodes that were marked to be deleted with SCIPcutoffNode
882
883NLP:
884- SCIPhasNLPContinuousNonlinearity() now returns SCIP_RETCODE and has additional argument result
885- removed SCIPnlrowGetNQuadVars(), SCIPnlrowGetQuadVars(), SCIPnlrowSearchQuadVar(), SCIPnlrowGetNQuadElems(), SCIPnlrowGetQuadElems(), SCIPnlrowGetQuadData()
886- renamed SCIPnlrowGetExprtree() to SCIPnlrowGetExpr() and changed return type to SCIP_EXPR*
887- removed arguments nquadvars, quadvars, nquadelems, quadelems from SCIPcreateNlRow(); argument expr(ession) is now of type SCIP_EXPR*
888- removed SCIPaddQuadVarToNlRow(), SCIPaddQuadVarsToNlRow(), SCIPaddQuadElementToNlRow(), SCIPaddQuadElementsToNlRow(), SCIPchgNlRowQuadElement(), SCIPsetNlRowExprtreeParam(), SCIPsetNlRowExprtreeParams()
889- renamed SCIPsetNlRowExprtree() to SCIPsetNlRowExpr() and changed type of expr(tree) argument to SCIP_EXPR*
890- SCIPenableNLP() is no longer allowed in stages INITSOLVE and SOLVING
891- removed SCIPaddLinearConsToNlpHeurSubNlp()
892- SCIPhasNLPSolution() now returns true also if a infeasible solution to the NLP exists; SCIPcreateNLPSol() can now also be used when only an infeasible solution to the NLP exists
893- renamed SCIPsolveNLP() to SCIPsolveNLPParam() and added parameter SCIP_NLPPARAM param
894- removed SCIPsolveDiveNLP(), use SCIPsolveNLPParam() instead
895
896NLPI:
897- removed SCIPnlpiCopy(), SCIPnlpiFree(), SCIPnlpiChgQuadCoefs(), SCIPnlpiChgNonlinCoef(), SCIPnlpiSetMessageHdlr()
898- removed SCIPnlpiCreate() from public API, use SCIPincludeNlpi() instead
899- removed SCIPnlpiGetSolverPointer() from public API, use SCIPgetNlpiSolverPointer() instead
900- removed SCIPnlpiCreateProblem() from public API, use SCIPcreateNlpiProblem() instead
901- removed SCIPnlpiFreeProblem() from public API, use SCIPfreeNlpiProblem() instead
902- removed SCIPnlpiGetProblemPointer() from public API, use SCIPgetNlpiProblemPointer() instead
903- removed SCIPnlpiAddVars() from public API, use SCIPaddNlpiVars() instead
904- removed SCIPnlpiAddConstraints() from public API, use SCIPaddNlpiConstraints() instead
905- removed SCIPnlpiSetObjective() from public API, use SCIPsetNlpiObjective() instead
906- removed SCIPnlpiChgVarBounds() from public API, use SCIPchgNlpiVarBounds() instead
907- removed SCIPnlpiChgConsSides() from public API, use SCIPchgNlpiConsSides() instead
908- removed SCIPnlpiDelVarSet() from public API, use SCIPdelNlpiVarSet() instead
909- removed SCIPnlpiDelConsSet() from public API, use SCIPdelNlpiConsSet() instead
910- removed SCIPnlpiChgLinearCoefs() from public API, use SCIPchgNlpiLinearCoefs() instead
911- removed SCIPnlpiChgExprtree() from public API, use SCIPchgNlpiExpr() instead
912- removed SCIPnlpiChgObjConstant() from public API, use SCIPchgNlpiObjConstant() instead
913- removed SCIPnlpiSetInitialGuess() from public API, use SCIPsetNlpiInitialGuess() instead
914- removed SCIPnlpiSolve() from public API, use SCIPsolveNlpiParam() instead
915- removed SCIPnlpiGetSolstat() from public API, use SCIPgetNlpiSolstat() instead
916- removed SCIPnlpiGetTermstat() from public API, use SCIPgetNlpiTermstat() instead
917- removed SCIPnlpiGetSolution() from public API, use SCIPgetNlpiSolution() instead
918- removed SCIPnlpiGetStatistics() from public API, use SCIPgetNlpiStatistics() instead
919- removed SCIPnlpiGetWarmstartSize()
920- removed SCIPnlpiGetWarmstartMemo()
921- removed SCIPnlpiSetWarmstartMemo()
922- removed SCIPnlpiGetIntPar()
923- removed SCIPnlpiSetIntPar()
924- removed SCIPnlpiGetRealPar()
925- removed SCIPnlpiSetRealPar()
926- removed SCIPnlpiGetStringPar(),
927- removed SCIPnlpiSetStringPar()
928- removed SCIPnlpiSetPriority() from public API, use SCIPsetNlpiPriority() instead
929- removed argument nlpi from SCIPincludeNlpi() and added name, description, priority,
930 nlpicopy, nlpifree, nlpigetsolverpointer, nlpicreateproblem, nlpifreeproblem, nlpigetproblempointer, nlpiaddvars, nlpiaddconstraints, nlpisetobjective, nlpichgvarbounds, nlpichgconssides, nlpidelvarset, nlpidelconsset, nlpichglinearcoefs, nlpichgexpr, nlpichgobjconstant, nlpisetinitialguess, nlpisolve, nlpigetsolstat, nlpigettermstat, nlpigetsolution, nlpigetstatistics, nlpidata
931- removed SCIPcreateNlpSolverAll(), use SCIPincludeNlpSolverAll() instead
932- removed SCIPcreateNlpSolverFilterSQP(), use SCIPincludeNlpSolverFilterSQP() instead
933- removed SCIPcreateNlpSolverIpopt(), use SCIPincludeNlpSolverIpopt() instead
934- removed SCIPcreateNlpSolverWorhp(), use SCIPincludeNlpSolverWorhp() instead
935- replaced argument BMS_BLKMEM* blkmem of SCIPnlpiOracleCreate() by SCIP* scip
936- added argument SCIP* scip to SCIPnlpiOracleFree(), SCIPnlpiOracleSetProblemName(), SCIPnlpiOracleAddVars(), SCIPnlpiOracleAddConstraints(), SCIPnlpiOracleSetObjective(), SCIPnlpiOracleChgVarBounds(), SCIPnlpiOracleChgConsSides(), SCIPnlpiOracleDelVarSet(), SCIPnlpiOracleDelConsSet(), SCIPnlpiOracleChgLinearCoefs(), SCIPnlpiOracleChgObjConstant(), SCIPnlpiOracleGetEvalCapability(), SCIPnlpiOracleEvalObjectiveValue(), SCIPnlpiOracleEvalConstraintValue(), SCIPnlpiOracleEvalConstraintValues(), SCIPnlpiOracleEvalObjectiveGradient(), SCIPnlpiOracleEvalConstraintGradient(), SCIPnlpiOracleGetJacobianSparsity(), SCIPnlpiOracleEvalJacobian(), SCIPnlpiOracleGetHessianLagSparsity(), SCIPnlpiOracleEvalHessianLag(), SCIPnlpiOraclePrintProblem(), SCIPnlpiOraclePrintProblemGams()
937- removed arguments nquadelems, quadelems, exprvaridxs, exprtrees from SCIPnlpiOracleAddConstraints(), added argument SCIP_EXPR** exprs
938- removed arguments nquadelems, quadelems, exprvaridxs, exprtree from SCIPnlpiOracleSetObjective(), added argument SCIP_EXPR* expr
939- replaced arguments isnewx of SCIPnlpiOracleEvalHessianLag() by two arguments isnewx_obj and isnewx_cons
940- removed SCIPnlpiOracleChgExprtree(), use SCIPnlpiOracleChgExpr() instead
941- removed SCIPnlpiOracleSetInfinity(), SCIPnlpiOracleGetInfinity(), SCIPnlpiOracleChgQuadCoefs(), SCIPnlpiOracleChgExprParam(), SCIPnlpiOracleGetMaxDegree()
942- removed SCIPnlpiOracleGetVarDegree() and SCIPnlpiOracleGetVarDegrees(), use SCIPnlpiOracleIsVarNonlinear() and SCIPnlpiOracleGetVarCounts(), respectively, instead
943- removed SCIPnlpiOracleGetConstraintDegree(), use SCIPnlpiOracleIsConstraintNonlinear() instead
944- removed argument messagehdlr from SCIPnlpiOraclePrintProblem() and SCIPnlpiOraclePrintProblemGams()
945- removed SCIPcreateNlpiProb(), use SCIPcreateNlpiProblemFromNlRows() instead
946- renamed SCIPupdateNlpiProb() to SCIPupdateNlpiProblem() and moved into scip_nlpi.{h,c}
947- renamed SCIPaddNlpiProbRows() to SCIPaddNlpiProblemRows() and moved into scip_nlpi.{h,c}
948- removed SCIPsetModifiedDefaultSettingsIpopt()
949- removed SCIPgetIpoptApplicationPointerIpopt(), use SCIPgetNlpiSolverPointer() instead
950- removed SCIPnlpStatisticsCreate(), SCIPnlpStatisticsFree(), SCIPnlpStatisticsGetNIterations(), SCIPnlpStatisticsGetTotalTime(), SCIPnlpStatisticsSetNIterations(), SCIPnlpStatisticsSetTotalTime(), the struct is public now
951- renamed LapackDsyev() to SCIPcallLapackDsyevIpopt()
952- renamed SCIPsolveLinearProb() to SCIPsolveLinearEquationsIpopt()
953
954Expression interpreter:
955- removed functions that operated with SCIPInterval
956- changed first argument of SCIPexprintCreate() to SCIP*
957- added SCIP* as first argument to SCIPexprintFree()
958- added SCIP* as first argument to SCIPexprintCompile(), changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA**
959- added arguments SCIP*, SCIP_EXPRINT*, and SCIP_EXPR* as first arguments to SCIPexprintFreeData()
960- renamed SCIPexprintGetExprtreeCapability() to SCIPexprintGetExprCapability();
961 added SCIP* as first argument, changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA*
962- removed SCIPexprintNewParametrization()
963- SCIPexprintEval(): added SCIP* as first argument, changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA*
964- removed SCIPexprintEvalInt()
965- SCIPexprintGrad(): added SCIP* as first argument, changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA*
966- removed SCIPexprintGradInt()
967- removed SCIPexprintHessianSparsityDense() and SCIPexprintHessianDense, use SCIPexprintHessianSparsity() and SCIPexprintHessian() instead
968
969Expressions:
970- removed SCIPexpropGetName(), use SCIPexprhdlrGetName() instead
971- removed SCIPexpropGetNChildren()
972- removed SCIPexprGetOperator(), use SCIPexprGetHdlr() instead
973- removed SCIPexprGetOpIndex(), SCIPexprGetOpReal(), SCIPexprGetOpData(), use SCIPexprGetData() instead
974- removed SCIPexprGetRealPowerExponent(), SCIPexprGetIntPowerExponent(), SCIPexprGetSignPowerExponent(), use SCIPgetExponentExprPow() instead
975- removed SCIPexprGetLinearCoefs(), SCIPexprGetLinearConstant(), use SCIPgetCoefsExprSum() and SCIPgetConstantExprSum() instead
976- removed SCIPexprGetQuadElements(), SCIPexprGetQuadConstant(), SCIPexprGetQuadLinearCoefs(), SCIPexprGetNQuadElements(), use SCIPexprGetQuadraticData(), SCIPexprGetQuadraticQuadTerm(), SCIPexprGetQuadraticBilinTerm() instead
977- removed SCIPexprGetMonomials(), SCIPexprGetNMonomials, SCIPexprGetPolynomialConstant(), SCIPexprGetMonomialCoef(), SCIPexprGetMonomialNFactors(), SCIPexprGetMonomialChildIndices(), SCIPexprGetMonomialExponents()
978- removed SCIPexprGetUserData(), SCIPexprHasUserEstimator(), SCIPexprGetUserEvalCapability()
979- removed SCIPexprCreate(), use SCIPcreateExpr() instead
980- removed SCIPexprCopyDeep(), use SCIPduplicateExpr() instead
981- removed SCIPexprFreeDeep(), use SCIPreleaseExpr() instead
982- removed SCIPexprFreeShallow()
983- removed SCIPexprAdd(), SCIPexprMulConstant()
984- removed SCIPexprCreateLinear(), use SCIPcreateExprSum() instead
985- replaced SCIPexprAddToLinear() by SCIPappendExprSumExpr()
986- replaced SCIPexprCreateQuadratic() by SCIPcreateExprQuadratic()
987- removed SCIPexprSortQuadElems()
988- removed SCIPexprCreatePolynomial(), SCIPexprAddMonomials(), SCIPexprChgPolynomialConstant(), SCIPexprMultiplyPolynomialByConstant(), SCIPexprMultiplyPolynomialByMonomial(), SCIPexprMultiplyPolynomialByPolynomial(), SCIPexprPolynomialPower()
989- removed SCIPexprMergeMonomials(), SCIPexprFreeMonomial(), SCIPexprSortMonomialFactors(), SCIPexprFindMonomialFactor(), SCIPexprAreMonomialsEqual(), SCIPexprAddMonomialFactors(), SCIPexprChgMonomialCoef(), SCIPexprMultiplyMonomialByMonomial(), SCIPexprMonomialPower(), SCIPexprMergeMonomialFactors(), SCIPexprSortMonomials()
990- replaced SCIPexprCreateMonomial() by SCIPcreateExprMonomial()
991- removed SCIPexprCreateUser(), use SCIPincludeExprhdlr() instead
992- removed SCIPexprHasParam(), SCIPexprGetMaxDegree(), SCIPexprGetVarsUsage()
993- replaced SCIPexprAreEqual() by SCIPcompareExpr()
994- replaced SCIPexprSimplify() by SCIPsimplifyExpr()
995- replaced SCIPexprEvalShallow() by SCIPcallExprEval()
996- replaced SCIPexprEval() by SCIPevalExpr()
997- replaced SCIPexprEvalIntShallow() by SCIPcallExprInteval()
998- replaced SCIPexprEvalInt() by SCIPevalExprActivity()
999- removed SCIPexprEvalUser(), SCIPexprEvalIntUser(), SCIPexprEstimateUser()
1000- replaced SCIPexprCheckCurvature() by SCIPcomputeExprCurvature()
1001- removed SCIPexprSubstituteVars(), use SCIPcopyExpr() instead
1002- removed SCIPexprReindexVars(), SCIPexprReindexParams()
1003- replaced SCIPexprPrint() by SCIPprintExpr()
1004- replaced SCIPexprParse() by SCIPparseExpr()
1005
1006Expression tree:
1007- removed SCIPexprtreeGetVars(), SCIPexprtreeSetVars(), SCIPexprtreeAddVars(), SCIPexprtreePrintWithNames(), SCIPexprtreeFindVar()
1008- removed SCIPexprtreeGetRoot(), SCIPexprtreeGetNVars(), SCIPexprtreeGetNParams(), SCIPexprtreeGetParamVals(), SCIPexprtreeSetParamVal(), SCIPexprtreeHasParam()
1009- removed SCIPexprtreeGetInterpreterData(), SCIPexprtreeSetInterpreterData(), SCIPexprtreeFreeInterpreterData()
1010- removed SCIPexprtreeGetMaxDegree()
1011- removed SCIPexprtreeEval(), use SCIPevalExpr() instead
1012- removed SCIPexprtreeEvalInt(), use SCIPevalExprActivity() instead
1013- removed SCIPexprtreePrint(), use SCIPprintExpr() instead
1014- removed SCIPexprtreeCreate()
1015- removed SCIPexprtreeCopy(), use SCIPduplicateExpr() instead
1016- removed SCIPexprtreeFree(), use SCIPreleaseExpr() instead
1017- removed SCIPexprtreeSetParams(), SCIPexprtreeGetVarsUsage()
1018- removed SCIPexprtreeSimplify(), use SCIPsimplifyExpr() instead
1019- removed SCIPexprtreeAddExpr()
1020- removed SCIPexprtreeCheckCurvature(), use SCIPcomputeExprCurvature() instead
1021- removed SCIPexprtreeSubstituteVars(), use SCIPcopyExpr() instead
1022- removed SCIPquadelemSort(), SCIPquadelemSortedFind(), SCIPquadelemSqueeze()
1023
1024Expression graph:
1025- removed SCIPexprgraphCaptureNode(), use SCIPcaptureExpr() instead
1026- removed SCIPexprgraphIsNodeEnabled()
1027- removed SCIPexprgraphGetNodeNChildren(), use SCIPexprGetNChildren() instead
1028- removed SCIPexprgraphGetNodeChildren(), use SCIPexprGetChildren() instead
1029- removed SCIPexprgraphGetNodeNParents(), SCIPexprgraphGetNodeParents(), SCIPexprgraphGetNodeDepth(), SCIPexprgraphGetNodePosition()
1030- removed SCIPexprgraphGetNodeOperator(), use SCIPexprGetHdlr() instead
1031- removed SCIPexprgraphGetNodeOperatorIndex(), SCIPexprgraphGetNodeOperatorReal(), use SCIPexprGetData() instead
1032- removed SCIPexprgraphGetNodeVar(), use SCIPgetVarExprVar() instead
1033- removed SCIPexprgraphGetNodeRealPowerExponent(), SCIPexprgraphGetNodeIntPowerExponent(), SCIPexprgraphGetNodeSignPowerExponent(), use SCIPgetExponentExprPow() instead
1034- removed SCIPexprgraphGetNodeLinearCoefs(), SCIPexprgraphGetNodeLinearConstant(), use SCIPgetCoefsExprSum(), SCIPgetConstantExprSum() instead
1035- removed SCIPexprgraphGetNodeQuadraticConstant(), SCIPexprgraphGetNodeQuadraticLinearCoefs(), SCIPexprgraphGetNodeQuadraticQuadElements(), SCIPexprgraphGetNodeQuadraticNQuadElements(), use SCIPexprGetQuadraticData(), SCIPexprGetQuadraticQuadTerm(), SCIPexprGetQuadraticBilinTerm() instead
1036- removed SCIPexprgraphGetNodePolynomialMonomials(), SCIPexprgraphGetNodePolynomialNMonomials(), SCIPexprgraphGetNodePolynomialConstant(), SCIPexprgraphGetNodePolynomialMonomialCurvature()
1037- removed SCIPexprgraphGetNodeUserData(), SCIPexprgraphHasNodeUserEstimator()
1038- removed SCIPexprgraphGetNodeBounds(), use SCIPexprGetActivity() instead
1039- removed SCIPexprgraphGetNodeVal(), use SCIPexprGetEvalValue() instead
1040- removed SCIPexprgraphGetNodeCurvature(), use SCIPexprGetCurvature() instead
1041- removed SCIPexprgraphCreateNode()
1042- removed SCIPexprgraphCreateNodeLinear(), use SCIPcreateExprSum() instead
1043- removed SCIPexprgraphCreateNodeQuadratic(), use SCIPcreateExprQuadratic() instead
1044- removed SCIPexprgraphCreateNodePolynomial(), SCIPexprgraphNodePolynomialAddMonomials()
1045- removed SCIPexprgraphCreateNodeUser(), removed SCIPexprgraphNodeSplitOffLinear(), SCIPexprgraphMoveNodeParents()
1046- removed SCIPexprgraphReleaseNode(), use SCIPreleaseExpr() instead
1047- removed SCIPexprgraphFreeNode(), use SCIPreleaseExpr() instead
1048- removed SCIPexprgraphEnableNode(), SCIPexprgraphDisableNode()
1049- removed SCIPexprgraphHasNodeSibling(), SCIPexprgraphAreAllNodeChildrenVars(), SCIPexprgraphHasNodeNonlinearAncestor()
1050- removed SCIPexprgraphPrintNode(), SCIPprintExpr() instead
1051- removed SCIPexprgraphTightenNodeBounds()
1052- removed SCIPexprgraphUpdateNodeBoundsCurvature(), use SCIPevalExprActivity() and SCIPcomputeExprCurvature() instead
1053- removed SCIPexprgraphGetDepth(), SCIPexprgraphGetNNodes(), SCIPexprgraphGetNodes(), SCIPexprgraphGetNVars(), SCIPexprgraphGetVars()
1054- removed SCIPexprgraphGetVarNodes(), SCIPexprgraphSetVarNodeValue(), SCIPexprgraphSetVarsBounds(), SCIPexprgraphSetVarBounds(), SCIPexprgraphSetVarNodeBounds(), SCIPexprgraphSetVarNodeLb(), SCIPexprgraphSetVarNodeUb(), SCIPexprgraphGetVarsBounds()
1055- removed SCIPexprgraphCreate(), SCIPexprgraphFree()
1056- removed SCIPexprgraphAddNode(), SCIPexprgraphAddVars(), SCIPexprgraphAddConst(), SCIPexprgraphAddExprtreeSum()
1057- removed SCIPexprgraphReplaceVarByLinearSum(), SCIPexprgraphFindVarNode(), SCIPexprgraphFindConstNode()
1058- replaced SCIPexprgraphPrintDot() by SCIPprintExprDotInit[2](), SCIPprintExprDot(), SCIPprintExprDotFinal()
1059- removed SCIPexprgraphEval(), use SCIPevalExpr() instead
1060- removed SCIPexprgraphPropagateVarBounds(), SCIPexprgraphPropagateNodeBounds()
1061- removed SCIPexprgraphCheckCurvature(), use SCIPcomputeExprCurvature() instead
1062- removed SCIPexprgraphSimplify(), use SCIPsimplifyExpr() instead
1063- removed SCIPexprgraphGetTree(), SCIPexprgraphGetSeparableTrees(), SCIPexprgraphGetSubtreeVarsUsage(), SCIPexprgraphGetSumTreesNSummands(), SCIPexprgraphGetSumTrees()
1064
1065Constraint handlers for NLP:
1066- removed SCIPincludeConshdlrAbspower()
1067- deprecated SCIPcreateConsAbspower() and SCIPcreateConsBasicAbspower(), use SCIPcreateConsBasicSignpowerNonlinear() instead
1068- deprecated SCIPgetNlRowAbspower(), use SCIPgetNlRowNonlinear() instead
1069- removed SCIPgetNonlinearVarAbspower(), SCIPgetLinearVarAbspower(), SCIPgetExponentAbspower(), SCIPgetOffsetAbspower(), SCIPgetCoefLinearAbspower(), SCIPgetLhsAbspower(), SCIPgetRhsAbspower()
1070- removed SCIPgetViolationAbspower(), use SCIPgetAbsViolationNonlinear() instead
1071- removed SCIPisConvexAbspower(), use SCIPhasExprCurvature() instead
1072- removed SCIPincludeConshdlrBivariate(), SCIPcreateConsBivariate(), SCIPcreateConsBasicBivariate()
1073- removed SCIPgetLinearVarBivariate(), SCIPgetLinearCoefBivariate(), SCIPgetExprtreeBivariate(), SCIPgetLhsBivariate(), SCIPgetRhsBivariate()
1074- removed SCIPincludeConshdlrQuadratic(), use SCIPincludeNlhdlrQuadratic() instead
1075- removed SCIPincludeQuadconsUpgrade()
1076- removed SCIPcreateConsQuadratic2(), SCIPcreateConsBasicQuadratic2()
1077- deprecated SCIPcreateConsBasicQuadratic(), use SCIPcreateConsBasicQuadraticNonlinear() instead
1078- deprecated SCIPcreateConsBasicQuadratic(), use SCIPcreateConsQuadraticNonlinear() instead
1079- deprecated SCIPaddConstantQuadratic(), use SCIPgetLhsNonlinear() and SCIPgetRhsNonlinear() instead
1080- deprecated SCIPaddLinearVarQuadratic(), use SCIPaddLinearVarNonlinear() instead
1081- deprecated SCIPaddQuadVarQuadratic(), use SCIPaddLinearVarNonlinear() and SCIPaddExprNonlinear() instead
1082- deprecated SCIPaddQuadVarLinearCoefQuadratic(), use SCIPaddLinearVarNonlinear() instead
1083- deprecated SCIPaddSquareCoefQuadratic(), use SCIPaddExprNonlinear() instead
1084- deprecated SCIPaddBilinTermQuadratic(), use SCIPaddExprNonlinear() instead
1085- deprecated SCIPchgLhsQuadratic(), use SCIPgetLhsNonlinear() instead
1086- deprecated SCIPchgRhsQuadratic(), use SCIPgetRhsNonlinear() instead
1087- deprecated SCIPgetNlRowQuadratic(), use SCIPgetNlRowNonlinear() instead
1088- removed SCIPgetNLinearVarsQuadratic(), SCIPgetLinearVarsQuadratic(), SCIPgetCoefsLinearVarsQuadratic(), SCIPgetNQuadVarTermsQuadratic(), SCIPgetQuadVarTermsQuadratic(), SCIPsortQuadVarTermsQuadratic(), SCIPfindQuadVarTermQuadratic(), SCIPgetNBilinTermsQuadratic(), SCIPgetBilinTermsQuadratic(), SCIPgetLhsQuadratic(), SCIPgetRhsQuadratic()
1089- removed SCIPgetLinvarMayDecreaseQuadratic(), SCIPgetLinvarMayIncreaseQuadratic()
1090- removed SCIPcheckCurvatureQuadratic() and SCIPisConvexConsQuadratic(), use SCIPcomputeExprQuadraticCurvature() instead
1091- removed SCIPisConvexQuadratic(), SCIPisConcaveQuadratic()
1092- removed SCIPgetViolationQuadratic() and SCIPgetFeasibilityQuadratic(), use SCIPgetAbsViolationNonlinear() instead
1093- removed SCIPisLinearLocalQuadratic(), SCIPaddToNlpiProblemQuadratic()
1094- removed SCIPchgLinearCoefQuadratic(), SCIPchgSquareCoefQuadratic(), SCIPchgBilinCoefQuadratic()
1095- renamed SCIPgetNAllBilinearTermsQuadratic() to SCIPgetNBilinTermsNonlinear() and changed argument from SCIP* to SCIP_CONSHDLR*
1096- renamed SCIPgetAllBilinearTermsQuadratic() to SCIPgetBilinTermsNonlinear() and replaced arguments by SCIP_CONSHDLR* and changed return type to SCIP_CONSNONLINEAR_BILINTERM*
1097- removed SCIPaddBilinearIneqQuadratic(), use SCIPinsertBilinearTermImplicitNonlinear() instead
1098- renamed SCIPcreateConsQuadratic() to SCIPcreateConsQuadraticNonlinear() and removed argument stickingatnode
1099- removed SCIPincludeConshdlrSOC()
1100- replaced SCIPcreateConsBasicSOC() by SCIPcreateConsBasicSOCNonlinear()
1101- deprecated SCIPcreateConsSOC(), use SCIPcreateConsBasicSOCNonlinear() instead
1102- deprecated SCIPgetNlRowSOC(), use SCIPgetNlRowNonlinear() instead
1103- removed SCIPgetNLhsVarsSOC(), SCIPgetLhsVarsSOC(), SCIPgetLhsCoefsSOC(), SCIPgetLhsOffsetsSOC(), SCIPgetLhsConstantSOC(), SCIPgetRhsVarSOC(), SCIPgetRhsCoefSOC(), SCIPgetRhsOffsetSOC(), use SCIPisSOCNonlinear() instead
1104- removed SCIPaddToNlpiProblemSOC()
1105- renamed SCIPincludeNonlinconsUpgrade() to SCIPincludeConsUpgradeNonlinear() and removed nodereform argument
1106- removed arguments nlinvars, linvars, lincoefs, nexprtrees, exprtrees, nonlincoefs, stickingatnode from SCIPcreateConsNonlinear() and added SCIP_EXPR* argument
1107- removed arguments nlinvars, linvars, lincoefs, nexprtrees, exprtrees, nonlincoefs from SCIPcreateConsBasicNonlinear() and added SCIP_EXPR* argument
1108- removed SCIPcreateConsNonlinear2(), SCIPcreateConsBasicNonlinear2()
1109- removed SCIPsetExprtreesNonlinear(), use SCIPchgExprNonlinear() instead
1110- removed SCIPaddExprtreesNonlinear()
1111- removed SCIPgetNLinearVarsNonlinear(), SCIPgetLinearVarsNonlinear(), SCIPgetLinearCoefsNonlinear()
1112- removed SCIPgetNExprtreesNonlinear(), SCIPgetExprtreesNonlinear(), SCIPgetExprtreeCoefsNonlinear(), SCIPgetExprgraphNodeNonlinear(), use SCIPgetExprNonlinear() instead
1113- removed argument scip from SCIPgetLhsNonlinear() and SCIPgetRhsNonlinear()
1114- removed SCIPcheckCurvatureNonlinear(), SCIPgetCurvatureNonlinear(), and SCIPgetExprtreeCurvaturesNonlinear(), use SCIPhasExprCurvature() instead
1115- renamed SCIPgetViolationNonlinear() to SCIPgetAbsViolationNonlinear()
1116- added arguments var and coef to SCIPgetLinvarMayDecreaseNonlinear() and SCIPgetLinvarMayIncreaseNonlinear() and changed return type to void
1117- removed SCIPgetExprgraphNonlinear()
1118- removed SCIPcomputeHyperplaneThreePoints(), use SCIPcomputeFacetVertexPolyhedralNonlinear() instead
1119
1120### New API functions
1121
1122- added SCIPallocClearMemory() and SCIPallocClearBlockMemory() to allocate a chunk of (block) memory
1123 that is initialized to zeros
1124- New internal functions for changing the default values of parameters:
1125 SCIPparamsetSetDefaultLongint(), SCIPparamsetSetDefaultReal(), SCIPparamsetSetDefaultChar(),
1126 SCIPparamsetSetDefaultString() and
1127 SCIPparamSetDefaultLongint(), SCIPparamSetDefaultReal(), SCIPparamSetDefaultChar(),
1128 SCIPparamSetDefaultString()
1129- new internal function SCIPisPackingPartitioningOrbitope() to check whether an orbitope is of
1130 packing or partitioning type
1131- new internal function SCIPcomputeOrbitVar() to compute the symmetry orbit of a variable
1132- added SCIPcalcFibHash(SCIP_Real) to hash a floating-point value to an unsigned integer
1133- added SCIPcomputeArraysIntersectionPtr() to compute intersection of two sorted arrays of pointers
1134- new function SCIPinterruptLP() (intended to be called from a different thread) that interrupts ongoing lp solve
1135- added SCIPcreateConsIndicatorGeneric() and SCIPcreateConsIndicatorGenericLinCons()
1136 which copy the interface of SCIPcreateConsIndicator() and SCIPcreateConsIndicatorLinCons() and
1137 add an activeone argument to specify whether the indicator constraint should be activated on 0 or 1.
1138 SCIPcreateConsIndicator() also adds a lessthanineq flag to choose whether the linear constraint is a less-than or greater-than inequality.
1139- added SCIPmarkDoNotAggrVar() to mark that a variable should not be aggregated
1140- added SCIPdoNotAggrVar() to query whether a variable should not be aggregated
1141- added SCIPdecompGetNBorderVars() and SCIPdecompGetNBorderConss() to get number of border variables/constraints
1142- added SCIPdecompGetVarsSize() and SCIPdecompGetConssSize() to get variable/constraint size for each block of a decomposition
1143- added SCIPincludeDialogDefaultBasic()
1144- added SCIPintervalAreDisjointEps(), SCIPintervalIntersectEps()
1145- added SCIPintervalEntropy()
1146- added SCIPintervalPropagateWeightedSum()
1147- added SCIPcalcRootNewton()
1148- added SCIPvarGetImplicVarBounds()
1149- added SCIPcreateRowprep(), SCIPfreeRowprep(), SCIPcopyRowprep(),
1150 SCIProwprepGetNVars(), SCIProwprepGetVars(), SCIProwprepGetCoefs(), SCIProwprepGetSide(), SCIProwprepGetSidetype(), SCIProwprepIsLocal(), SCIProwprepGetName(), SCIProwprepGetNModifiedVars(), SCIProwprepGetModifiedVars(),
1151 SCIProwprepReset(), SCIProwprepAddSide(), SCIProwprepAddConstant(), SCIProwprepSetSidetype(), SCIProwprepSetLocal(), SCIProwprepRecordModifications(),
1152 SCIPprintRowprep(), SCIPprintRowprepSol(), SCIPensureRowprepSize(), SCIPaddRowprepTerm(), SCIPaddRowprepTerms(), SCIPgetRowprepViolation(), SCIPisRowprepViolationReliable(),
1153 SCIPmergeRowprepTerms(), SCIPcleanupRowprep(), SCIPcleanupRowprep2(), SCIPscaleupRowprep(), SCIPscaleRowprep(),
1154 SCIPgetRowprepRowConshdlr(), SCIPgetRowprepRowCons(), SCIPgetRowprepRowSepa()
1155- added SCIPsetClockEnabled()
1156- added SCIPisSolveInterrupted() to check whether SCIPinterruptSolve() has been called
1157- added SCIPgetNPresolRounds()
1158- added SCIPgetNUnfixedLPCols()
1159- moved SCIPhistoryGetInferenceSum() and SCIPhistoryGetAvgConflictlength() from internal to public API
1160
1161Expression handler:
1162- added SCIPincludeExprhdlr(), SCIPgetExprhdlrs(), SCIPgetNExprhdlrs(), SCIPfindExprhdlr()
1163- added SCIPgetExprhdlrVar(), SCIPgetExprhdlrValue(), SCIPgetExprhdlrSum(), SCIPgetExprhdlrProduct(), SCIPgetExprhdlrPower()
1164- added SCIPexprhdlrSetCopyFreeHdlr(), SCIPexprhdlrSetCopyFreeData(), SCIPexprhdlrSetPrint(), SCIPexprhdlrSetParse(), SCIPexprhdlrSetCurvature(), SCIPexprhdlrSetMonotonicity(), SCIPexprhdlrSetIntegrality(), SCIPexprhdlrSetHash(), SCIPexprhdlrSetCompare(), SCIPexprhdlrSetDiff(), SCIPexprhdlrSetIntEval(), SCIPexprhdlrSetSimplify(), SCIPexprhdlrSetReverseProp(), SCIPexprhdlrSetEstimate()
1165- added SCIPexprhdlrGetName(), SCIPexprhdlrGetDescription(), SCIPexprhdlrGetPrecedence(), SCIPexprhdlrGetData(), SCIPexprhdlrHasPrint(), SCIPexprhdlrHasBwdiff(), SCIPexprhdlrHasFwdiff(), SCIPexprhdlrHasIntEval(), SCIPexprhdlrHasEstimate(), SCIPexprhdlrHasInitEstimates(), SCIPexprhdlrHasSimplify(), SCIPexprhdlrHasCurvature(), SCIPexprhdlrHasMonotonicity(), SCIPexprhdlrHasReverseProp()
1166- added SCIPexprhdlrComp()
1167- added SCIPexprhdlrGetNIntevalCalls(), SCIPexprhdlrGetIntevalTime(), SCIPexprhdlrGetNReversepropCalls(), SCIPexprhdlrGetReversepropTime(), SCIPexprhdlrGetNCutoffs(), SCIPexprhdlrGetNDomainReductions(), SCIPexprhdlrIncrementNDomainReductions(), SCIPexprhdlrGetNEstimateCalls(), SCIPexprhdlrGetEstimateTime(), SCIPexprhdlrGetNBranchings(), SCIPexprhdlrIncrementNBranchings(), SCIPexprhdlrGetNSimplifyCalls(), SCIPexprhdlrGetSimplifyTime(), SCIPexprhdlrGetNSimplifications()
1168- added SCIPprintExpressionHandlerStatistics()
1169- added SCIPincludeExprhdlrEntropy(), SCIPcreateExprEntropy(), SCIPisExprEntropy()
1170- added SCIPincludeExprhdlrErf(), SCIPcreateExprErf(), SCIPisExprErf()
1171- added SCIPcreateExprAbs(), SCIPincludeExprhdlrAbs(), SCIPisExprAbs()
1172- added SCIPcreateExprExp(), SCIPincludeExprhdlrExp(), SCIPisExprExp()
1173- added SCIPcreateExprLog(), SCIPincludeExprhdlrLog(), SCIPisExprLog()
1174- added SCIPcreateExprPow(), SCIPcreateExprSignpower(), SCIPincludeExprhdlrPow(), SCIPincludeExprhdlrSignpower(), SCIPisExprSignpower(), SCIPgetExponentExprPow(), SCIPisExprPower()
1175- added SCIPincludeExprhdlrProduct(), SCIPcreateExprProduct(), SCIPgetCoefExprProduct(), SCIPisExprProduct()
1176- added SCIPincludeExprhdlrSum(), SCIPcreateExprSum(), SCIPsetConstantExprSum(), SCIPappendExprSumExpr(), SCIPmultiplyByConstantExprSum(), SCIPgetCoefsExprSum(), SCIPgetConstantExprSum(), SCIPisExprSum()
1177- added SCIPincludeExprhdlrSin(), SCIPcreateExprSin(), SCIPincludeExprhdlrCos(), SCIPcreateExprCos(), SCIPisExprSin(), SCIPisExprCos()
1178- added SCIPincludeExprhdlrValue(), SCIPcreateExprValue(), SCIPgetValueExprValue(), SCIPisExprValue()
1179- added SCIPincludeExprhdlrVar(), SCIPcreateExprVar(), SCIPgetVarExprVar(), SCIPisExprVar()
1180- added SCIPincludeExprhdlrVaridx(), SCIPcreateExprVaridx(), SCIPisExprVaridx(), SCIPgetIndexExprVaridx(), SCIPsetIndexExprVaridx()
1181
1182Expression:
1183- added SCIPcaptureExpr(), SCIPreleaseExpr(), SCIPexprGetNUses()
1184- added SCIPexprGetHdlr(), SCIPexprGetData(), SCIPexprSetData(), SCIPexprGetOwnerData()
1185- added SCIPevalExpr(), SCIPgetExprNewSoltag(), SCIPexprGetEvalValue(), SCIPexprGetEvalTag()
1186- added SCIPevalExprGradient(), SCIPevalExprHessianDir(), SCIPexprGetDerivative(), SCIPexprGetDot(), SCIPexprGetBardot(), SCIPexprGetDiffTag()
1187- added SCIPevalExprActivity(), SCIPexprGetActivity(), SCIPexprGetActivityTag(), SCIPexprSetActivity()
1188- added SCIPcomputeExprCurvature(), SCIPexprGetCurvature(), SCIPexprSetCurvature()
1189- added SCIPcomputeExprIntegrality(), SCIPexprIsIntegral(), SCIPexprSetIntegrality()
1190- added SCIPcheckExprQuadratic(), SCIPfreeExprQuadratic(), SCIPevalExprQuadratic(), SCIPprintExprQuadratic(), SCIPcomputeExprQuadraticCurvature()
1191- added SCIPexprGetQuadraticData(), SCIPexprGetQuadraticQuadTerm(), SCIPexprGetQuadraticBilinTerm(), SCIPexprAreQuadraticExprsVariables()
1192- added SCIPcreateExpr(), SCIPcreateExpr2(), SCIPcreateExprQuadratic(), SCIPcreateExprMonomial()
1193- added SCIPappendExprChild(), SCIPreplaceExprChild(), SCIPremoveExprChildren()
1194- added SCIPduplicateExpr(), SCIPduplicateExprShallow(), SCIPcopyExpr()
1195- added SCIPparseExpr()
1196- added SCIPprintExpr(), SCIPdismantleExpr()
1197- added SCIPprintExprDotInit(), SCIPprintExprDotInit2(), SCIPprintExprDot(), SCIPprintExprDotFinal(), SCIPshowExpr()
1198- added SCIPcompareExpr(), SCIPhashExpr()
1199- added SCIPsimplifyExpr(), SCIPreplaceCommonSubexpressions()
1200- added SCIPgetExprNVars(), SCIPgetExprVarExprs()
1201- added SCIPcallExprPrint(), SCIPcallExprCurvature(), SCIPcallExprMonotonicity(), SCIPcallExprEval(), SCIPcallExprEvalFwdiff(), SCIPcallExprInteval(), SCIPcallExprEstimate(), SCIPcallExprInitestimates(), SCIPcallExprSimplify(), SCIPcallExprReverseprop()
1202- added SCIPexprcurvPowerInv(), SCIPexprcurvMonomialInv()
1203
1204Expression iterator:
1205- added SCIPcreateExpriter(), SCIPfreeExpriter()
1206- added SCIPexpriterIsInit(), SCIPexpriterInit()
1207- added SCIPexpriterRestartDFS(), SCIPexpriterSetStagesDFS(), SCIPexpriterGetCurrent(), SCIPexpriterGetStageDFS(), SCIPexpriterGetChildIdxDFS(), SCIPexpriterGetChildExprDFS(), SCIPexpriterGetParentDFS()
1208- added SCIPexpriterGetCurrentUserData(), SCIPexpriterGetChildUserDataDFS(), SCIPexpriterGetExprUserData(), SCIPexpriterSetCurrentUserData(), SCIPexpriterSetExprUserData(), SCIPexpriterSetChildUserData()
1209- added SCIPexpriterGetNext(), SCIPexpriterSkipDFS(), SCIPexpriterIsEnd()
1210- added SCIPexprintHessianSparsity(), SCIPexprintHessian()
1211
1212Constraint handlers for NLP:
1213- added SCIPgetCurBoundsTagNonlinear(), SCIPgetLastBoundRelaxTagNonlinear(), SCIPincrementCurBoundsTagNonlinear()
1214- added SCIPgetVarExprHashmapNonlinear()
1215- added SCIPprocessRowprepNonlinear()
1216- added SCIPassumeConvexNonlinear()
1217- added SCIPcollectBilinTermsNonlinear(), SCIPgetBilinTermIdxNonlinear(), SCIPgetBilinTermNonlinear(), SCIPevalBilinAuxExprNonlinear(), SCIPinsertBilinearTermExistingNonlinear(), SCIPinsertBilinearTermImplicitNonlinear()
1218- added SCIPcomputeFacetVertexPolyhedralNonlinear()
1219- added SCIPgetExprNonlinear()
1220- added SCIPcheckQuadraticNonlinear(), SCIPchgLhsNonlinear(), SCIPchgRhsNonlinear(), SCIPchgExprNonlinear(), SCIPaddExprNonlinear()
1221- added SCIPgetRelViolationNonlinear()
1222- added SCIPgetExprNLocksPosNonlinear(), SCIPgetExprNLocksNegNonlinear(), SCIPgetExprAuxVarNonlinear(), SCIPgetExprNEnfosNonlinear(), SCIPgetExprEnfoDataNonlinear(), SCIPsetExprEnfoAuxValueNonlinear()
1223- added SCIPgetExprNPropUsesActivityNonlinear(), SCIPgetExprNSepaUsesActivityNonlinear(), SCIPgetExprNAuxvarUsesNonlinear(), SCIPregisterExprUsageNonlinear()
1224- added SCIPgetExprAbsOrigViolationNonlinear(), SCIPgetExprAbsAuxViolationNonlinear(), SCIPgetExprRelAuxViolationNonlinear()
1225- added SCIPgetExprBoundsNonlinear(), SCIPtightenExprIntervalNonlinear(), SCIPmarkExprPropagateNonlinear()
1226- added SCIPaddExprViolScoreNonlinear(), SCIPaddExprsViolScoreNonlinear(), SCIPgetExprViolScoreNonlinear()
1227- added SCIPgetExprPartialDiffNonlinear(), SCIPgetExprPartialDiffGradientDirNonlinear()
1228- added SCIPevalExprQuadraticAuxNonlinear()
1229- added SCIPincludeNlhdlrNonlinear(), SCIPfindNlhdlrNonlinear(), SCIPgetNNlhdlrsNonlinear(), SCIPgetNlhdlrsNonlinear(), SCIPgetNlhdlrExprDataNonlinear()
1230- added SCIPcreateConsQuadraticNonlinear() and SCIPcreateConsBasicQuadraticNonlinear() to create a nonlinear constraint that is quadratic
1231- added SCIPcreateConsBasicSignpowerNonlinear() to create a nonlinear constraint that looks like the former abspower or signpower constraints
1232
1233Nonlinear Handler:
1234- added SCIPincludeNlhdlrBilinear(), SCIPgetExprsBilinear(), SCIPgetExprsdataBilinear(), SCIPgetNExprsBilinear(), SCIPaddIneqBilinear()
1235- added SCIPincludeNlhdlrConvex(), SCIPincludeNlhdlrConcave(), SCIPhasExprCurvature()
1236- added SCIPincludeNlhdlrDefault()
1237- added SCIPincludeNlhdlrPerspective()
1238- added SCIPincludeNlhdlrQuadratic()
1239- added SCIPincludeNlhdlrQuotient()
1240- added SCIPincludeNlhdlrSoc(), SCIPisSOCNonlinear(), SCIPfreeSOCArraysNonlinear()
1241- added SCIPnlhdlrSetCopyHdlr(), SCIPnlhdlrSetFreeHdlrData(), SCIPnlhdlrSetFreeExprData(), SCIPnlhdlrSetInitExit(), SCIPnlhdlrSetProp(), SCIPnlhdlrSetSepa()
1242- added SCIPnlhdlrGetName(), SCIPnlhdlrGetDesc(), SCIPnlhdlrGetDetectPriority(), SCIPnlhdlrGetEnfoPriority(), SCIPnlhdlrIsEnabled(), SCIPnlhdlrGetData()
1243- added SCIPnlhdlrHasIntEval(), SCIPnlhdlrHasReverseProp(), SCIPnlhdlrHasInitSepa(), SCIPnlhdlrHasExitSepa(), SCIPnlhdlrHasEnfo(), SCIPnlhdlrHasEstimate()
1244- added SCIPnlhdlrComp()
1245
1246NLPI:
1247- added SCIPgetNlpiSolverPointer(), SCIPcreateNlpiProblem(), SCIPfreeNlpiProblem(), SCIPgetNlpiProblemPointer(), SCIPaddNlpiVars(), SCIPaddNlpiConstraints(), SCIPsetNlpiObjective(), SCIPchgNlpiVarBounds(), SCIPchgNlpiConsSides(), SCIPdelNlpiVarSet(), SCIPdelNlpiConsSet(), SCIPchgNlpiLinearCoefs(), SCIPchgNlpiExpr(), SCIPchgNlpiObjConstant(), SCIPsetNlpiInitialGuess(), SCIPsolveNlpiParam(), SCIPgetNlpiSolstat(), SCIPgetNlpiTermstat(), SCIPgetNlpiSolution(), SCIPgetNlpiStatistics()
1248- added SCIPincludeNlpSolverAll()
1249- added SCIPincludeNlpSolverFilterSQP(), SCIPgetSolverNameFilterSQP(), SCIPgetSolverDescFilterSQP(), SCIPisFilterSQPAvailableFilterSQP()
1250- added SCIPincludeNlpSolverIpopt()
1251- added SCIPincludeNlpSolverWorhp()
1252- added SCIPnlpiOracleChgExpr()
1253- added SCIPcreateNlpiProblemFromNlRows()
1254- added SCIPnlpiOracleGetObjectiveConstant()
1255- added SCIPnlpiOracleIsVarNonlinear(), SCIPnlpiOracleGetVarCounts(), SCIPnlpiOracleIsConstraintNonlinear()
1256- added SCIPnlpiGetNProblems(), SCIPnlpiGetProblemTime(), SCIPnlpiGetNSolves(), SCIPnlpiGetSolveTime(), SCIPnlpiGetEvalTime(), SCIPnlpiGetNIterations(), SCIPnlpiGetNTermStat(), SCIPnlpiGetNSolStat(), SCIPnlpiMergeStatistics()
1257- added SCIPmergeNLPIStatistics(), SCIPprintNLPIStatistics()
1258- added SCIPnlpiOracleResetEvalTime(), SCIPnlpiOracleGetEvalTime()
1259- added SCIPaddNlpiProblemNlRows()
1260
1261Cut Selector:
1262- added SCIPincludeCutsel(), SCIPincludeCutselBasic(), SCIPsetCutselCopy(), SCIPsetCutselFree(), SCIPsetCutselInit(), SCIPsetCutselExit(), SCIPsetCutselInitsol(), SCIPsetCutselExitsol(), SCIPfindCutsel(), SCIPgetCutsels(), SCIPgetNCutsels(), SCIPsetCutselPriority()
1263- added SCIPcutselGetName(), SCIPcutselGetData(), SCIPcutselGetDesc(), SCIPcutselGetPriority(), SCIPcutselSetData(), SCIPcutselIsInitialized(), SCIPcutselGetSetupTime(), SCIPcutselGetTime()
1264
1265### Command line interface
1266### Interfaces to external software
1267
1268- removed GAMS interface (originally in interfaces/gams) and reading capability of gms reader;
1269 the removed interface was a poorly maintained copy of the GAMS/SCIP interface that is available at
1270 https://github.com/coin-or/GAMSlinks
1271- integrated AMPL interface into main SCIP executable, that is, added possibility to use SCIP executable as solver in AMPL
1272 (AMPL calls solver with name of .nl file and -AMPL as arguments; SCIP will then attempt to solve the problem and write an AMPL solution file)
1273- the ZIMPL interface has been updated to support ZIMPL 3.4.1;
1274 the minimal required ZIMPL version is now 3.4.1
1275
1276### Changed parameters
1277
1278- Extended range of parameter "misc/usesymmetry" from [0,3] to [0,7], changed default from 3 to 5
1279- deleted parameter "constraints/orbitope/usedynamicprop"
1280- changed type of parameter "propagating/symmetry/recomputerestart" from SCIP_Bool to int with range [0,2]
1281- deleted parameter "propagating/symmetry/disableofrestart"
1282- parameter "heuristics/padm/original" is now an advanced parameter
1283- removed constraints/nonlinear/linfeasshift, constraints/nonlinear/reformulate, constraints/nonlinear/maxexpansionexponent, constraints/nonlinear/sepanlpmincont
1284- removed constraints/nonlinear/upgrade/abspower
1285- removed constraints/nonlinear/upgrade/and, use constraints/nonlinear/reformbinprodsand instead
1286- removed constraints/nonlinear/upgrade/bivariate
1287- removed constraints/nonlinear/upgrade/quadratic, use nlhdlr/quadratic/enabled instead
1288- changed default of constraints/nonlinear/maxproprounds from 1 to 10
1289- replaced constraints/nonlinear/enfocutsremovable by constraints/nonlinear/rownotremovable
1290- replaced constraints/nonlinear/cutmaxrange by separating/maxcoefratiofacrowprep
1291- removed constraints/quadratic/sepafreq, constraints/quadratic/propfreq, constraints/quadratic/proptiming, constraints/quadratic/eagerfreq, constraints/quadratic/maxprerounds, constraints/quadratic/delaysepa, constraints/quadratic/delayprop, constraints/quadratic/presoltiming
1292- removed constraints/quadratic/replacebinaryprod, use constraints/nonlinear/reformbinprodsfac instead
1293- removed constraints/quadratic/empathy4and, use constraints/nonlinear/reformbinprodsand instead
1294- removed constraints/quadratic/binreforminitial, constraints/quadratic/binreformbinaryonly, constraints/quadratic/binreformmaxcoef
1295- removed constraints/quadratic/cutmaxrange, constraints/quadratic/mincurvcollectbilinterms, constraints/quadratic/linearizeheursol, constraints/quadratic/checkcurvature, constraints/quadratic/checkfactorable, constraints/quadratic/checkquadvarlocks, constraints/quadratic/linfeasshift
1296- removed constraints/quadratic/maxdisaggrsize, constraints/quadratic/disaggrmergemethod, constraints/quadratic/maxproprounds, constraints/quadratic/maxproproundspresolve, constraints/quadratic/enfolplimit, constraints/quadratic/sepanlpmincont, constraints/quadratic/enfocutsremovable
1297- removed constraints/quadratic/gaugecuts, constraints/quadratic/interiorcomputation, constraints/quadratic/projectedcuts, constraints/quadratic/branchscoring, constraints/quadratic/usebilinineqbranch, constraints/quadratic/bilinineqmaxseparounds,
1298- removed constraints/quadratic/minscorebilinterms, use nlhdlr/bilinear/enabled instead
1299- removed constraints/quadratic/upgrade/linear, constraints/quadratic/upgrade/abspower, constraints/quadratic/upgrade/bivariate, constraints/quadratic/upgrade/bounddisjunction
1300- removed constraints/quadratic/upgrade/soc, use nlhdlr/soc/enabled instead
1301- renamed constraints/quadratic/upgrade/setppc to constraints/nonlinear/upgrade/setppc
1302- removed constraints/abspower/sepafreq, constraints/abspower/propfreq, constraints/abspower/proptiming, constraints/abspower/eagerfreq, constraints/abspower/maxprerounds, constraints/abspower/delaysepa, constraints/abspower/delayprop, constraints/abspower/presoltiming
1303- removed constraints/abspower/cutmaxrange, constraints/abspower/projectrefpoint, constraints/abspower/preferzerobranch, constraints/abspower/branchminconverror, constraints/abspower/addvarboundcons, constraints/abspower/linfeasshift, constraints/abspower/dualpresolve, constraints/abspower/sepainboundsonly, constraints/abspower/sepanlpmincont, constraints/abspower/enfocutsremovable
1304- removed constraints/bivariate/sepafreq, constraints/bivariate/propfreq, constraints/bivariate/proptiming, constraints/bivariate/eagerfreq, constraints/bivariate/maxprerounds, constraints/bivariate/delaysepa, constraints/bivariate/delayprop, constraints/bivariate/presoltiming
1305- removed constraints/bivariate/cutmaxrange, constraints/bivariate/linfeasshift, constraints/bivariate/maxproprounds, constraints/bivariate/ninitlprefpoints, constraints/bivariate/enfocutsremovable
1306- removed constraints/soc/sepafreq, constraints/soc/propfreq, constraints/soc/proptiming, constraints/soc/eagerfreq, constraints/soc/maxprerounds, constraints/soc/delaysepa, constraints/soc/delayprop, constraints/soc/presoltiming
1307- removed constraints/soc/projectpoint, constraints/soc/nauxvars, constraints/soc/glineur, constraints/soc/sparsify, constraints/soc/sparsifymaxloss, constraints/soc/sparsifynzgrowth, constraints/soc/linfeasshift, constraints/soc/nlpform, constraints/soc/sepanlpmincont, constraints/soc/enfocutsremovable, constraints/soc/disaggregate
1308- removed constraints/soc/generalsocupgrade, use nlhdlr/soc/compeigenvalues instead
1309- changed default of presolving/qpkktref/maxrounds from -1 to 0
1310- changed default of propagating/obbt/onlynonconvexvars from FALSE to TRUE
1311- changed default of heuristics/subnlp/resolvetolfactor from 0.001 to 1.0
1312- removed heuristics/subnlp/nlpoptfile, use nlpi/ipopt/optfile instead
1313- removed separating/convexproj/nlptimelimit
1314- removed separating/gauge/nlptimelimit
1315- removed heuristics/subnlp/nlptimelimit and heuristics/subnlp/nlpiterlimit
1316- removed heuristics/subnlp/resolvetolfactor and heuristics/subnlp/resolvefromscratch
1317- changed default of heuristics/subnlp/itermin to 20
1318- renamed heuristics/subnlp/iteroffset to heuristics/subnlp/nodesoffset
1319- renamed heuristics/subnlp/iterquotient to heuristics/subnlp/nodesfactor
1320- removed heuristics/subnlp/runalways, use heuristics/subnlp/nodesoffset=INT_MAX and heuristics/subnlp/successrateexp = 0.0 instead
1321- removed heuristics/subnlp/minimprove, heuristics/multistart/nlpminimpr
1322- Removed parameters for strongcg separator: separating/strongcg/..., i.e.,
1323 maxrounds, maxroundsroot, maxsepacutsroot, maxsepacuts, dynamiccuts. One can control the
1324 strongcg behavior throught the parameters of sepa_gomory.
1325- renamed separating/{minortho,minorthoroot,objparalfac,intsupportfac} to cutselection/hybrid/{minortho,minorthoroot,objparalweight,intsupportweight}
1326
1327### New parameters
1328
1329- It is now possible to add orbitope constraints to handle symmetries even if not all variables
1330 in a component of the symmetry group are binary. This feature can be enabled using the
1331 parameter "propagating/symmetry/onlybinorbitope".
1332
1333- new parameter "propagating/symmetry/sstleaderrule" to select a rule for selecting the
1334 leader in SST cuts
1335- new parameter "propagating/symmetry/ssttiebreakrule" to select a tiebreak rule for selecting the
1336 leader in SST cuts
1337- new parameter "propagating/symmetry/sstleadervartype" to select the possible variable types
1338 for a leader in SST cuts
1339- new parameter "propagating/symmetry/addconflictcuts" to control whether SST cuts are added if
1340 a binary leader variable is in conflict with a variable in its orbit
1341- new parameter "propagating/symmetry/sstaddcuts" to control whether SST cuts are added
1342- new parameter "propagating/symmetry/sstmixedcomponents" to control whether SST cuts are added
1343 if a symmetry component contains variables of different types
1344- new parameter "propagating/symmetry/detectsubgroups" to search for orbitopes defined by subgroups
1345- new parameter "propagating/symmetry/addweaksbcs" to add Schreier Sims cuts for a single
1346 variable orbit in case an orbitope subgroup is detected
1347- new parameter "propagating/symmetry/addstrongsbcs" to add symretope facets for a single
1348 variable orbit on which the symmetry group acts like a symmetric group
1349- new parameter "propagating/symmetry/maxnconsssubgroup" to control up to which number of
1350 constraints subgroups are detected
1351- new parameter "propagating/symmetry/preferlessrows" to control whether orbitopes with
1352 smallest number of rows shall be computed by the subgroup detection heuristic
1353- new parameter "propagating/symmetry/usedynamicprop" to control if rows of full orbitope
1354 shall be ordered dynamically in propagation
1355- new parameter "separating/filtercutpoolrel" to control whether cutpool uses
1356 a dynamic strategy to separate only cuts with high relative efficacy
1357- if run from AMPL: display/statistics to enable printing detailed solve statistics after solve
1358- if run from AMPL: display/logfile to specify name of file to write SCIP log to (additionally to writing to stdout)
1359- constraints/nonlinear/propauxvars, constraints/nonlinear/varboundrelax, constraints/nonlinear/varboundrelaxamount, constraints/nonlinear/conssiderelaxamount
1360- constraints/nonlinear/vpmaxperturb, constraints/nonlinear/vpadjfacetthresh, constraints/nonlinear/vpdualsimplex
1361- constraints/nonlinear/bilinmaxnauxexprs, constraints/nonlinear/forbidmultaggrnlvar, constraints/nonlinear/checkvarlocks, constraints/nonlinear/violscale
1362- constraints/nonlinear/reformbinprods, constraints/nonlinear/reformbinprodsand, constraints/nonlinear/reformbinprodsfac
1363- constraints/nonlinear/tightenlpfeastol, constraints/nonlinear/propinenforce, constraints/nonlinear/weakcutthreshold, constraints/nonlinear/strongcutmaxcoef, constraints/nonlinear/strongcutefficacy, constraints/nonlinear/forcestrongcut, constraints/nonlinear/enfoauxviolfactor, constraints/nonlinear/weakcutminviolfactor
1364- constraints/nonlinear/branching/aux, constraints/nonlinear/branching/external, constraints/nonlinear/branching/highviolfactor, constraints/nonlinear/branching/highscorefactor, constraints/nonlinear/branching/violweight, constraints/nonlinear/branching/dualweight, constraints/nonlinear/branching/pscostweight, constraints/nonlinear/branching/domainweight, constraints/nonlinear/branching/vartypeweight, constraints/nonlinear/branching/scoreagg, constraints/nonlinear/branching/violsplit, constraints/nonlinear/branching/pscostreliable
1365- constraints/nonlinear/linearizeheursol
1366- nlhdlr/default/enabled
1367- nlhdlr/convex/enabled, nlhdlr/convex/detectsum, nlhdlr/convex/extendedform, nlhdlr/convex/cvxquadratic, nlhdlr/convex/cvxsignomial, nlhdlr/convex/cvxprodcomp, nlhdlr/convex/handletrivial
1368- nlhdlr/concave/enabled, nlhdlr/concave/detectsum, nlhdlr/concave/cvxquadratic, nlhdlr/concave/cvxsignomial, nlhdlr/concave/cvxprodcomp, nlhdlr/concave/handletrivial
1369- nlhdlr/bilinear/enabled, nlhdlr/bilinear/useinteval, nlhdlr/bilinear/usereverseprop, nlhdlr/bilinear/maxseparoundsroot, nlhdlr/bilinear/maxseparounds, nlhdlr/bilinear/maxsepadepth
1370- nlhdlr/perspective/enabled, nlhdlr/perspective/maxproprounds, nlhdlr/perspective/mindomreduction, nlhdlr/perspective/minviolprobing, nlhdlr/perspective/probingonlyinsepa, nlhdlr/perspective/probingfreq, nlhdlr/perspective/convexonly, nlhdlr/perspective/tightenbounds, nlhdlr/perspective/adjrefpoint
1371- nlhdlr/quadratic/enabled, nlhdlr/quadratic/useintersectioncuts, nlhdlr/quadratic/usestrengthening, nlhdlr/quadratic/useboundsasrays, nlhdlr/quadratic/ncutslimit, nlhdlr/quadratic/ncutslimitroot, nlhdlr/quadratic/maxrank, nlhdlr/quadratic/mincutviolation, nlhdlr/quadratic/minviolation, nlhdlr/quadratic/atwhichnodes, nlhdlr/quadratic/nstrengthlimit, nlhdlr/quadratic/ignorebadrayrestriction, nlhdlr/quadratic/ignorehighre
1372- nlhdlr/quotient/enabled
1373- nlhdlr/soc/enabled, nlhdlr/soc/mincutefficacy, nlhdlr/soc/compeigenvalues
1374- propagating/obbt/createlincons
1375- propagating/symmetry/onlybinarysymmetry
1376- separating/minor/priority, separating/minor/freq, separating/minor/maxbounddist, separating/minor/delay, separating/minor/expbackoff, separating/minor/maxminorsconst, separating/minor/maxminorsfac, separating/minor/mincutviol, separating/minor/maxrounds, separating/minor/maxroundsroot, separating/minor/ignorepackingconss
1377- separating/rlt/priority, separating/rlt/freq, separating/rlt/maxbounddist, separating/rlt/delay, separating/rlt/expbackoff, separating/rlt/maxncuts, separating/rlt/maxunknownterms, separating/rlt/maxusedvars, separating/rlt/maxrounds, separating/rlt/maxroundsroot, separating/rlt/onlyeqrows, separating/rlt/onlycontrows, separating/rlt/onlyoriginal, separating/rlt/useinsubscip, separating/rlt/useprojection, separating/rlt/detecthidden, separating/rlt/hiddenrlt, separating/rlt/addtopool, separating/rlt/goodscore, separating/rlt/badscore, separating/rlt/objparalweight, separating/rlt/efficacyweight, separating/rlt/dircutoffdistweight, separating/rlt/goodmaxparall, separating/rlt/maxparall
1378- separating/interminor/usestrengthening, separating/interminor/usebounds, separating/interminor/mincutviol, separating/interminor/maxrounds, separating/interminor/maxroundsroot
1379- table/cons_nonlinear/active, table/nlhdlr/active, table/exprhdlr/active, table/nlpi/active, table/nlhdlr_bilinear/active, table/nlhdlr_quadratic/active
1380- expr/log/minzerodistance, expr/pow/minzerodistance
1381- benders/default/maxslackvarcoef to specify maximal coefficient for slack variables; if exceeded, slack variables are fixed to zero
1382- nlpi/ipopt/optfile to specify name of Ipopt options file to use for every solve with Ipopt
1383- nlpi/ipopt/print_level, nlpi/ipopt/hsllib, nlpi/ipopt/pardisolib, nlpi/ipopt/linear_solver, nlpi/ipopt/linear_system_scaling, nlpi/ipopt/nlp_scaling_method, nlpi/ipopt/mu_strategy, nlpi/ipopt/hessian_approximation
1384- nlpi/ipopt/warm_start_push
1385- timing/nlpieval
1386- heuristics/subnlp/iterinit, heuristics/subnlp/ninitsolves, heuristics/subnlp/successrateexp
1387- heuristics/subnlp/expectinfeas, heuristics/subnlp/opttol, heuristics/subnlp/feastolfactor
1388- heuristics/subnlp/presolveemphasis, heuristics/subnlp/setcutoff
1389- new parameters "branching/inference/conflictprio" and "branching/inference/cutoffprio" that allow
1390 using the different score criteria in inference branching hierarchically
1391- new parameters "heuristics/alns/nodesquotmin", "heuristics/alns/maxcallssamesol" and "heuristics/alns/initduringroot"
1392 to control neighborhoods in ALNS
1393- new parameter "benders/default/benderscut/optimality/mir" to control whether mixed-integer rounding procedure is applied to Benders optimality cuts
1394- new parameter "misc/avoidmemout" to try to avoid running into memory limit
1395- cutselection/hybrid/dircutoffdistweight, cutselection/hybrid/efficacyweight, cutselection/hybrid/intsupportweight, cutselection/hybrid/objparalweight, cutselection/hybrid/priority
1396- new parameter "decomposition/disablemeasures" to disable expensive measures in SCIPcomputeDecompStats()
1397- new parameter "presolving/milp/probfilename" filename to write the problem to a file before MILP presolving starts
1398
1399### Data structures
1400
1401- removed quadratic terms from NLROWs
1402- removed SCIP_NLPPAR_INFINITY from SCIP_NLPPARAM enum
1403- added types SYM_OPTYPE, SYM_CONSTTYPE, SYM_RHSTYPE, SYM_EXPRDATA
1404- removed class SCIPInterval
1405- removed enum SCIP_EXPROP
1406- removed union SCIP_EXPROPDATA, added SCIP_EXPRDATA
1407- removed struct SCIP_EXPRTREE, use SCIP_EXPR instead
1408- removed structs SCIP_QUADELEM, SCIP_EXPRDATA_QUADRATIC, SCIP_EXPRDATA_MONOMIAL, SCIP_EXPRDATA_POLYNOMIAL, SCIP_EXPRDATA_USER
1409- removed structs SCIP_EXPRGRAPHNODE, SCIP_EXPRGRAPH
1410- removed type SCIP_EXPRBOUNDSTATUS
1411- removed struct SCIP_USEREXPRDATA
1412- added enum SCIP_MONOTONE
1413- added structs SCIP_EXPRHDLR, SCIP_EXPRHDLRDATA
1414- added union SCIP_EXPRITER_USERDATA
1415- added enum SCIP_EXPRITER_TYPE
1416- added structs SCIP_EXPRITERDATA, SCIP_EXPRITER
1417- added type SCIP_EXPRPRINT_WHAT, struct SCIP_EXPRPRINTDATA
1418- removed enum SCIP_BIVAR_CONVEXITY
1419- removed structs SCIP_QUADVAREVENTDATA, SCIP_QUADVARTERM, SCIP_BILINTERM
1420- added structs SCIP_CONSNONLINEAR_AUXEXPR, SCIP_CONSNONLINEAR_BILINTERM
1421- added type SCIP_NLHDLR_METHOD
1422- added structs SCIP_NLHDLR, SCIP_NLHDLRDATA, SCIP_NLHDLREXPRDATA
1423- enum SCIP_NLPPARAM has been changed to a struct that holds values of parameters for an NLP solve
1424- removed SCIP_NLPPAR_OPTFILE/optfile from SCIP_NLPPARAM
1425- added SCIP_NLPTERMSTAT_INTERRUPT to SCIP_NLPTERMSTAT enum; returned from NLP solver if SCIPinterruptSolve() has been called
1426- renamed SCIP_NLPTERMSTAT_TILIM to SCIP_NLPTERMSTAT_TIMELIMIT
1427- renamed SCIP_NLPTERMSTAT_ITLIM to SCIP_NLPTERMSTAT_ITERLIMIT
1428- renamed SCIP_NLPTERMSTAT_LOBJLIM to SCIP_NLPTERMSTAT_LOBJLIMIT
1429- renamed SCIP_NLPTERMSTAT_NUMERR to SCIP_NLPTERMSTAT_NUMERICERROR
1430- renamed SCIP_NLPTERMSTAT_EVALERR to SCIP_NLPTERMSTAT_EVALERROR
1431- renamed SCIP_NLPTERMSTAT_MEMERR to SCIP_NLPTERMSTAT_OUTOFMEMORY
1432- renamed SCIP_NLPTERMSTAT_LICERR to SCIP_NLPTERMSTAT_LICENSEERROR
1433- added evaltime to SCIP_NLPSTATISTICS
1434- added structs SCIP_CUTSEL, SCIP_CUTSELDATA
1435
1436Deleted files
1437-------------
1438
1439- interfaces/gams/∗
1440- interfaces/ampl/∗
1441- src/nlpi/∗
1442- src/scip/cons_bivariate.{c,h}
1443- src/scip/pub_misc_nonlinear.h
1444- src/scip/misc_nonlinear.c
1445- src/scip/scip_nonlinear.{c,h}
1446- src/scip/sepa_strongcg.{h|c}
1447
1448Unit tests
1449----------
1450
1451- added cons/linear/nonlinupgd.c
1452- added cons/nonlinear/addcons.c
1453- added cons/nonlinear/bilinhash.c
1454- added cons/nonlinear/check.c
1455- added cons/nonlinear/copy.c
1456- added cons/nonlinear/create_nlrow.c
1457- added cons/nonlinear/curvature.c
1458- added cons/nonlinear/glbconss.c
1459- added cons/nonlinear/hessian.c
1460- added cons/nonlinear/locks.c
1461- added cons/nonlinear/nlhdlr.c
1462- added cons/nonlinear/nlhdlr_bilinear.c
1463- added cons/nonlinear/nlhdlr_concave.c
1464- added cons/nonlinear/nlhdlr_convex.c
1465- added cons/nonlinear/nlhdlr_perspective.c
1466- added cons/nonlinear/nlhdlr_quadratic.c
1467- added cons/nonlinear/nlhdlr_quotient.c
1468- added cons/nonlinear/nlhdlr_soc.c
1469- added cons/nonlinear/parse.c
1470- added cons/nonlinear/presolve.c
1471- added cons/nonlinear/propagate.c
1472- added cons/nonlinear/readers.c
1473- added cons/nonlinear/reformbinprods.c
1474- added cons/nonlinear/repair.c
1475- added cons/nonlinear/transform.c
1476- added cons/nonlinear/vertexpolyhedral.c
1477- removed cons/nonlinear/getCoeffsAndConstantFromLinearExpr.c
1478- removed cons/soc/upgrade.c
1479- added expr/abs/estimation.c
1480- added expr/commonsubexprs.c
1481- added expr/compare.c
1482- added expr/copy.c
1483- added expr/cos/cos.c
1484- added expr/cos/estimation.c
1485- added expr/curvature.c
1486- added expr/derivative.c
1487- added expr/entropy/entropy.c
1488- added expr/entropy/estimation.c
1489- added expr/eval.c
1490- added expr/exp/estimation.c
1491- added expr/free.c
1492- added expr/getvarexprs.c
1493- added expr/hash.c
1494- added expr/hessian.c
1495- added expr/integrality.c
1496- added expr/iterator.c
1497- added expr/log/estimation.c
1498- added expr/monotonicity.c
1499- added expr/parse.c
1500- added expr/pow/estimation.c
1501- added expr/pow/pow.c
1502- added expr/product/estimation.c
1503- added expr/quad.c
1504- added expr/simplify.c
1505- added expr/sin/estimation.c
1506- added expr/sin/sin.c
1507- added expr/sum/estimation.c
1508- added nlpi/exprinterpret.c
1509- speedup test nlpi:solveQP in nlpi/nlpi.c
1510- added test projection:transitivity in prob/obbt.c
1511- added reader/nl.c
1512- added test intervalarith:sincos in scip/intervalarith.c
1513- added sepa/minor.c
1514- added sepa/rlt/cuts.c
1515- added sepa/rlt/product_detection.c
1516- added sepa/rlt/separation.c
1517- added tests test_compute_symmetry:expr{1,2,3,4} in symmetry/compute.c
1518
1519Build system
1520------------
1521
1522- the separate NLPI library has been integrated into the main SCIP library;
1523 uses of NLPILIBFILE or NLPILIBSRC in Makefiles that use make/make.project
1524 should be removed
1525
1526### Cmake
1527
1528- replace flag PARASCIP by THREADSAFE
1529- option AMPL is now ON by default
1530- add -D_XOPEN_SOURCE=600 cflag for compilation on systems other than windows
1531- add compile options directly instead of modifying CMAKE_C_FLAGS and CMAKE_CXX_FLAGS
1532
1533### Makefile
1534
1535- prefix PKG_CONFIG_PATH with Ipopt's pkgconfig dir instead of postfixing
1536- replace flag PARASCIP by THREADSAFE
1537- flag AMPL is now true by default
1538- libscip has been renamed to libscipbase and libscipsolver has been renamed to libscip
1539 in order to have the same library names for makefiles and cmake. For downward
1540 compatibility libscipsolver still exists (as a link).
1541
1542Fixed bugs
1543----------
1544
1545- fixed handling of multi-aggregation in cons_symresack and cons_orbisack
1546- SCIPgetLowerbound() now consistently returns infinity when status is infeasible
1547- improved the likelihood that a solution that satisfies the nonlinear constraints in the transformed (presolved) problem is also feasible for the original problem
1548- worked around a problem with derivatives of pow at 0 with non-integer exponents in CppAD
1549- fixed that setting of feasiblity and optimiality tolerance for NLP relaxation was overwritten with defaults when solving NLP
1550- fixed variance computation in t-value computation in hypothesis testing of reliability branching
1551- fixed potential overflow in cuts.c:evaluateLiftingFunctionKnapsack()
1552- do not transfer dual reductions to main SCIP in sepa_rapidlearning if strong dual reductions are forbidden
1553- fixed a bug in cons_setppc.c:removeDoubleAndSingletonsAndPerformDualpresolve() which led to wrong variable aggregations
1554- added missing redundancy check to coefficient tightening routine in cons_varbound that led to wrong variable locks
1555- added a check of numerics to avoid wrong reductions in cons_linear.c:simplifyInequalities()
1556- fixed a bug in cons_logicor.c regarding fixed variables that were not removed
1557- presol_milp.c handles variable fixings, suggested by PaPILO, more carefully to cover all cases that can appear
1558- fixed several reproducability bugs that led to different solving paths across multiple runs with one SCIP environment
1559- fixed check of limits/absgap, which was incorrectly applied to the scaled objective of the transformed problem
1560
1561Miscellaneous
1562-------------
1563
1564- in LP, use absolute instead of relative tolerances to check whether solutions from LP solver are primal feasible
1565- when a restart occurs, SCIP now asserts (during EXITSOLVE) that all relaxation-only variables are unlocked and
1566 only captured by the transformed problem.
1567- Avoid redundant calls to LP solver when LP is already flushed and solved
1568- In SCIPdebugMsg(), SCIPsetDebugMsg(), SCIPstatDebugMsg() strip directory from filename.
1569- Recompute activity of rows when checking LP solutions instead of trusting the value given by the LP solver
1570- The define NPARASCIP has been replaced by SCIP_THREADSAFE
1571- Parameters are not reset to their default values before activating an emphasis setting; this now allows to combine
1572 different emphasis settings.
1573- If a lazy bound is set to a value that is tighter than the current global bound, then the global bound is now tightened accordingly.
1574
1575@page RN70 Release notes for SCIP 7.0
1576
1577@section RN703 SCIP 7.0.3
1578*************************
1579
1580Interface changes
1581-----------------
1582
1583### New API functions
1584
1585- added function SCIPwithDebugSol() to determine whether SCIP was compiled with WITH_DEBUG_SOLUTION
1586
1587- New function SCIPcreateConsBounddisjunctionRedundant() and SCIPcreateConsBasicBounddisjunctionRedundant() that allow
1588 the input to contain redundant literals.
1589
1590### Changed API functions
1591
1592- added __attribute__((format(printf,,,))) to variadic SCIP message printing functions;
1593 this enables warnings about mismatches between format string and variadic function arguments if using GCC.
1594
1595### Interfaces to external software
1596
1597- removed MATLAB interface from interfaces/matlab
1598
1599Build system
1600------------
1601
1602- Compilation will now also work in a raw tarball of the scip git repository
1603
1604### Cmake
1605
1606- Make find_package more verbose and require packages to be found. Now enabled packages that are not found result in an error.
1607
1608Fixed bugs
1609----------
1610
1611- Fixed numerical bug by creating and checking the empty solution when problem vanishes in presolving.
1612- Fixed several bugs in reoptimization.
1613- Fixed bug in cons_bounddisjunction in which a constraint leads to a cutoff.
1614- Fixed bug in reoptimization by avoiding redundant literals for bound disjunctions.
1615- Replace wrong usage of CMAKE_BINARY_DIR by PROJECT_BINARY_DIR in CMake system
1616- Fixed lpi_glop to use absl flag instead of GFlags
1617- Fixed invalid initialization of limits/softtime parameter in cons_components
1618- Fixed MIN macro not defined in some cases.
1619- Safeguard some API methods for querying solving statistics against segmentation faults after SCIPpresolve()
1620- Fixed unfreed solution in concurrent solving
1621- Make sure that logicor constraints are enforced/separated if genlogicor is true in cons_indicator.
1622 Thus, do not change constraints/logicor/sepafreq anymore, but output warning.
1623- Fixed assert that assumed infeasibility cannot occur in presol_boundshift.
1624- Fixed sign bug during creation of conflict constraints with almost zero left-hand side.
1625- Disabled call of conflict handler for conflict sets that contain relaxation-only variables.
1626- Fixed bug in cons_symresack by initializing all constraint data in constrans
1627- Avoid allowing the upgrade of linear constraints corresponding to indicators in propagation of nodes.
1628- Fixed bug in computing lex. min/max faces in dynamic orbitope propagation.
1629- Limit vbounds propagator to one sweep through all bounds per call in order to avoid an infinite loop.
1630- Fixed mismatches between formatter strings and arguments in calls to SCIP message printing functions.
1631
1632Miscellaneous
1633-------------
1634
1635- To avoid performance variablity during reoptimization, the active constraints are now stored in the same order as in the
1636 original problem.
1637- Added workaround for bug in MSVS 2019 when compiling CppAD source.
1638- The original order of variables is now only restored after presolve if `randomization/permutevars` is set to FALSE.
1639
1640@section RN702 SCIP 7.0.2
1641*************************
1642
1643Features
1644--------
1645
1646- Extended check for valid variable and constraint names in PIP writer.
1647- Indicator constraints now write the name of the linear constraint in CIP format. This avoids a complicated
1648 name matching during parsing. The old format is still supported.
1649- The objective scale and offset are now taken into account when reading/writing problems in lp/mps/fzn/pip format.
1650 This often changes the behavior when writing transformed problems.
1651
1652Performance improvements
1653------------------------
1654
1655Examples and applications
1656-------------------------
1657
1658- Add c++ Sudoku example
1659
1660Interface changes
1661-----------------
1662
1663### Deleted and changed API methods
1664
1665- deprecated SCIPsetParam(); use SCIPsetIntParam(), SCIPsetRealParam(), etc, instead
1666
1667### New API functions
1668
1669- new function SCIPcolGetVarProbindex() for accessing the probindex of a variable corresponding to a column
1670- added new sorting functions SCIPsortPtrRealRealBoolBool()
1671
1672Fixed bugs
1673----------
1674
1675- Fixed a sign bug occuring for some cases in the computation of the directed cutoff distance
1676- Fixed overflow in inference information of cumulative constraint handler
1677- Fixed problem with propfreq == 0 in cons_linear.c
1678- Fixed aggregation heuristic in sepa_aggregation.c to not use local rows when that is requested nor modifiable rows
1679- Fixed problem with incompatibility of symmetry handling in Benders decomposition
1680- Fixed parsing of small number in CIP format of nonlinear constraint
1681- Fixed problem in upgrading full orbitopes to partitioning orbitopes
1682- Fixed treatment of negated variables in parsing orbitope constraints
1683- Fixed potential indexing error in prop_vbounds.c
1684- Fixed bug in writing fzn format
1685- Revert to old parameter value when parameter change is rejected in PARAMCHGD callback
1686- Fixed order of linker flags when building AMPL interface with cmake system.
1687- Fixed bug with ofsymcomptiming == 0: now symmetry is actually computed
1688- Improved separation for SOC constraint with multiaggregated variable on right-hand-side.
1689- Fixed bug in presol_boundshift: do not shift non-active variables
1690- Fixed bug in domain propagation for SOC constraints with negative coefficient for variable on right-hand-side.
1691- Fixed bug with multi-aggregated integer variables in cons_xor.
1692- Fixed bug with changed number of variables in storing relaxation solution in probing/diving.
1693- Fixed issues with scip statistics
1694- Fixed issue with multi-aggregated variables
1695- Fixed issue in with buffer memory in cons_cumulative
1696
1697@section RN701 SCIP 7.0.1
1698*************************
1699
1700Build system
1701------------
1702
1703### Cmake
1704
1705- Fixed cmake module for Ipopt to support Ipopt 3.13
1706- Added cmake variable BLISS_LIBRARY_DIR to pass a bliss library
1707- Added warning to require minimal GCC version 4.8
1708- Renamed FindCriterion cmake findmodule to FindCRITERION
1709
1710### Makefile
1711
1712- Updated make/make.project for macOS
1713- Add SANITZERFLAGS (only OPT=dbg) to LDFLAGS also if SHARED=true (and rename SANITZERFLAGS to SANITIZERFLAGS)
1714- Fixed GCC version check in make/make.linux.gnu.dbg
1715
1716Fixed bugs
1717----------
1718
1719- Fixed handling of constant term in quadratic objective of pip-reader
1720- Fixed incorrect value string for parameter estimation/completiontype
1721- Fixed initialization of first LP which led to wrong output about LPs not resolved correctly
1722- Fixed bug in SCIPcutpoolClear() function not clearing internal datastructures properly
1723- Fixed inability to set a value in a solution if it was within epsilon to the current value
1724- Fixed problems for linking optimized code with debug library of SCIP (and vice versa) by moving debug-only members
1725 to end of SCIP structs
1726
1727Miscellaneous
1728-------------
1729
1730- Variables that are marked as relaxation-only are no longer checked against debug solutions if
1731 they are captured by the transformed problem only.
1732
1733@section RN700 SCIP 7.0.0
1734*************************
1735
1736Features
1737--------
1738
1739- Using the parameter "propagating/symmetry/recomputerestart" one can now decide to recompute symmetries after a
1740 restart or not. Previously one could just turn off symmetry computation after a restart. If orbital fixing
1741 has found a reduction before the restart occured, symmetries have to be updated to ensure correctness.
1742 To this end, the user can decide via "propagating/symmetry/disableofrestart" whether orbital fixing is disabled or
1743 whether symmetries are recomputed.
1744
1745- extended relaxators statistics in solve statistics about information on number of cutoffs, improved bounds, etc.
1746
1747- extends SMPS file reader for the stochastic information, the sto files, to read a lower bound for the discrete
1748 scenarios. The lower bound is used when creating the auxiliary variables for Benders' decomposition.
1749
1750- extended Benders framework to solve NLPs and generate optimality and feasibility cuts from their solution
1751 when the subproblem is convex nonlinear.
1752
1753- extended Benders framework to create copies of Benders decompositions that can be used in a multithreading environment
1754
1755- additional functionality has been added to enable the transfer of Benders' decomposition cuts between different SCIP
1756 instances, e.g., when used in UG
1757
1758- LP rows (SCIP_ROW) can now store pointer to a constraint from which the row originates
1759
1760- Trust region, a new LNS heuristic, has been added to SCIP as both a standalone primal heuristic heur_trustregion.c
1761 and as a neighborhood inside of Adaptive Large Neighborhood Search (heur_alns.c). This heuristic is designed to improve the
1762 heuristic performance of the Benders' decomposition algorithm. It builds upon the successful trust region approaches
1763 applied to Benders' decomposition.
1764
1765- Modularity of symmetry handling has been increased. It is now possible to use orbitopes (i.e., polyhedral symmetry
1766 handling techniques) and orbital fixing on the same instance.
1767
1768- cut strengthening enabled within the Benders' decomposition framework. This uses a mix of the Improved Magnanti-Wong
1769 method and Kelly's method. The cut strengthening is enabled by setting the paramemter
1770 "benders/<bendersname>/cutstrengthenenabled" to TRUE. The parameters "cutstrengthenmult", "noimprovelimit" and
1771 "corepointperturb" control the behavior of the cut strengthening method. Additionally, the parameter
1772 "cutstrengthenintpoint" allows the user to specify the solution that is used to initialize the core point. The options
1773 are the first LP solution, the first integer feasible solution, a relative interior point, a solution vector of all
1774 ones and a solution vector of all zeros. Also, the core point can be reinitialized after each update to the incumbent
1775 solution.
1776
1777- added option to adjust weights of different scores in relpscost (hybrid) branching rule based on degeneracy information
1778 and skip strong branching for very high degeneracy rates
1779
1780- added new SCIP_DECOMP* object to store user decompositions. The user can specify one or several decompositions by assigning variable
1781 and/or constraint labels either through the API or by reading a file in DEC format (which is one of the formats that GCG writes).
1782 This format specifies constraint labels, variable labels are inferred from that. The decomposition is transformed after presolving.
1783- statistics regarding the number of blocks, the largest and smallest blocks, the border, and the constraint graph are printed for the original decomposition,
1784 and for each decomposition after presolving.
1785- the decomposition can be used as initial decomposition for the Benders functionality of SCIP.
1786- new subsection "How to provide a problem decomposition" in the SCIP documentation
1787
1788- GINS heuristic can make use of a user-provided decomposition labels in two ways:
1789 1. by selecting a block of variables that maximizes the potential, and randomly selecting a start variable for the neighborhood and/or
1790 2. by selecting an interval of consecutive blocks as neighborhood, until fixing rate is reached. In this case, no variable is randomly selected.
1791
1792- extend potential parameter of GINS to allow computation based on local LP solution, as well
1793
1794- new primal heuristic Adaptive Diving, which registers all publicly available dive sets from other diving heuristics.
1795 At each call, it selects one of the available dive sets based on the user's score type choice (heuristics/adaptivediving/scoretype).
1796 During the solution process, the heuristics learns online which divesets reach the best score, and executes them more frequently.
1797 The statistic output for Diving heuristics has been extended to incorporate the statistics of each dive set within Adaptive diving.
1798
1799- Added new penalty alternating direction method (PADM) primal heuristic that splits the problem into several sub-SCIPs
1800 according to a user-provided decomposition. The sub-SCIPs are solved on an alternating basis until a feasible solution of
1801 the original problem is found.
1802
1803- Symmetry handling constraints (cons_orbisack, cons_orbitope, cons_symresack) now have an additional parameter to encode
1804 whether they are model constraints, i.e., define the problem, or whether they are only present to handle symmetries.
1805
1806- The symmetry code has been completely restructured. The presolvers presol_symbreak and presol_symmetry as well as the propagator
1807 prop_orbitalfixing have been merged into the single propagator prop_symmetry to avoid storing the same information
1808 multiple times. This propagator is now responsible for adding symmetry handling constraints as well as activating orbital
1809 fixing. Moreover, the new file symmetry.c contains general functions for symmetry computations like orbit computations.
1810
1811- Variables can now be marked as "relaxation-only". This flag should be used to introduce new variables that are required
1812 to define a relaxation, but that are not part of any checked constraints. Essentially, these variables should only be used
1813 in the current SCIP solve and disregarded after a restart or in SCIP copies. Hence, these variables are not copied by SCIPcopy and
1814 SCIPgetVarCopy, they are currently not used in conflict constraints, and cuts involving them are not upgraded to linear constraints.
1815 Relaxation-only variables cannot appear in the objective function.
1816
1817- The OSiL reader now supports nonlinear expressions of type "signpower".
1818
1819- Expressions of form abs(x)^p * x in a nonlinear constraint are now sometimes recognized and handled by abspower constraints.
1820
1821- If polyhedral symmetry handling methods are used (cons_orbisack, cons_orbitope, cons_symresack), it is now possible to
1822 recompute symmetries if a restart occured.
1823
1824- upgrade some more quadratic constraints to second-order cone constraints, that is,
1825 handle linear binary variables as if squared in simple upgrade and
1826 do not require bounds for variables that have a zero entry in the computed eigenvectors in the non-simple upgrade
1827
1828- new variable event when changing the variable type
1829
1830- It is no longer necessary to provide a SCIP pointer for the subproblem in SCIPaddBendersSubproblem if custom solving
1831 methods are defined. A NULL pointer can be supplied to SCIPaddBendersSubproblem. In this case, no internal Benders'
1832 cut generation methods can be used.
1833
1834- Using the parameter "constraints/symresack/checkmonotonicity" one can now decide to upgrade to packing/partitioning
1835 symresacks even if the underlying permutation is not monotone.
1836
1837- New branching rule `vanillafullstrong`, mostly for scientific purpose, with the following features:
1838 1) no cutoff or domain reduction: only branching;
1839 2) idempotent (optional): leave SCIP, as much as possible, in the same state before / after the strong branching calls
1840 - basically, do not update any statistic;
1841 3) donotbranch (optional): do no perform branching. So that the brancher can be called as an oracle only
1842 (on which variable would you branch ? But do not branch please);
1843 4) scoreall (optional): keep scoring variables, even if infeasibility is detected;
1844 5) collectscores (optional): store the candidate scores from the last call, which can then be retrieved by calling SCIPgetVanillafullstrongData();
1845 6) integralcands (optional): consider integral candidates for branching,
1846 i.e., get candidates from SCIPgetPseudoBranchCands() instead of SCIPgetLPBranchCands().
1847
1848- If a reference value (misc/referencevalue) is given, the primal-reference and reference-dual integrals are calculated automatically and printed within the SCIP statistics.
1849
1850- Locally valid cuts / rows are now considered for dual proof analysis when `conflict/uselocalrows` is set to TRUE.
1851
1852- Linking variables in the linking constraint handler (cons_linking.{ch}) can now be integer or continuous. The coefficients of the binary variables are therefore now stored as SCIP_Real.
1853
1854- To save memory, it is now possible to remove all variables from the internal symmetry data structures that are
1855 not affected by any symmetry.
1856
1857- Allow to filter first variables from orbits and transfer pseudo cost information to variables in orbit
1858
1859- Add integration of external MILP presolve library as a SCIP presolver plugin that runs on MILP problems
1860
1861- Parallelisation can be used when applying Benders' decomposition. There are two different forms of parallelisation
1862 available. The first is applying Benders' decomposition within a parallel branch-and-bound. This is achieved through
1863 the integration with the UG framework. The second is the use of shared memory parallelisation for solving the Benders'
1864 decomposition subproblems. A priority queue has been added to help with load balancing.
1865
1866- The Benders' decomposition framework can handle MINLPs. If a convex relaxation of the MINLP exists, then this is
1867 solved to generate optimality and feasibility cuts. The extensions to the framework are:
1868 - New generic solving methods to solve convex NLP subproblems.
1869 - Modification to benderscut_opt and benderscut_feas to enable the generation of cuts from convex NLPs.
1870 - Addition of benderscut_feasalt to generate feasibility cuts from an alternative subproblem that minimises the
1871 violation of infeasible problems.
1872 - Better handling of subproblem solution results
1873
1874- Adds a feasibility phase to the Benders' decomposition subproblem solving methods. The feasibility phase adds slack
1875 variables to each of the constraints to ensure feasibility of the subproblem. A large coefficient is given to these
1876 slack variables in the objective function to penalise constraint violations. The coefficients are progressively
1877 increased until all slack variables take the value 0.0.
1878
1879- Improved convexity check for Benders' decomposition subproblems. The constraints of the subproblem are now checked for
1880 convexity in the initialisation of the Benders' decomposition algorithm. This enables the solving of convex NLPs as
1881 Benders' decomposition subproblems.
1882
1883- Benders' decomposition can be applied using decomposition supplied in the DEC format. To apply Benders' decomposition
1884 the parameters decomposition/benderslabels and decomposition/applybenders must be set to TRUE.
1885
1886- new event handler event_estim.c/h that approximates search tree completion and estimates tree size
1887 to trigger restarts; many approximations of search tree completion and estimation, including WBE, SSG, and tree profile method
1888- new display column that reports approx. search tree completion during the search, and an overview in the statistics table
1889- added resources (script, tutorial, test data) to adapt tree size estimation to user instances.
1890
1891- Orbital Fixing uses a list of variables that have been fixed globally since the computation of symmetries to filter
1892 symmetries. Previously, some plugins were disabled, which is not necessary anymore.
1893
1894- A new presolver "dualsparsify" was added. It tries to combine columns (i.e. variables) to cancel nonzero coefficients in the constraint matrix.
1895
1896- The presolver "tworowbnd" was implemented with better performance.
1897
1898- To be able to calculate better bounds for the dual variables, the presolver "dualinfer" was extended by the ability to perform convex combinations of continuous columns.
1899
1900- allow disabling of pricers during solving process
1901
1902- added emphasis setting for numerically challenging instances
1903
1904Performance improvements
1905------------------------
1906
1907- Extended cut presolving by removing variables that been fixed at their bounds
1908
1909- Improved branching point selection when branching on externals branching candidates. Instead of using exactly the
1910 LP solution, a point closer to the middle of the variables domain is chosen.
1911
1912- Matrix presolvers that do not work on incomplete matrices now skip matrix creation if unsupported constraint types are detected.
1913
1914- consLockBenders callback implemented to add down locks on the Benders' decomposition auxiliary variables and
1915 up and down locks per subproblem for all master problem variables. This allows the use of presolving and propagation
1916 with Benders' decomposition.
1917
1918- improved performance of orbital fixing in several ways:
1919 store permutations in transposed form to improve cache efficency;
1920 reverse order to speed up filtering of permutations;
1921 handle variables globally fixed to 1 in list;
1922 use event handler to catch global fixings;
1923 speed up orbit computations;
1924 change handling of restarts;
1925 use only permutations that can contribute to a variable's orbit;
1926
1927- allow rapid learning at local nodes
1928
1929- allow to recompute cut without using fractional values for sepa_cgmip
1930
1931- restrict the number of the clique table nonzeros relative to the number of problem nonzeros, which could be a performance bottleneck.
1932
1933- variable fixings of LP face heuristic are now computed earlier; subproblem creation is skipped if not enough variables are fixed.
1934
1935- Improved domcol presolver to not require a complete representation of all constraints in the matrix
1936
1937- performance improvement of adaptive large neighborhood search heuristic on merely continuous problems. The heuristic
1938 stops if presolving in the sub-SCIP fixes less than 50 % of the current target fixing rate over all variables
1939 (including continuous).
1940
1941- reduce memory usage in symmetry detection by a staggered allocation with decreasing overhead for larger instances
1942
1943- improved full orbitope propagation using a static implementation or a dynamic reordering of orbitope rows by a global rank function
1944
1945- improved detection of packing/partitioning orbitopes
1946
1947- enable an in-tree restart if after a reasonable initialization, the estimated size of the remaining tree is large.
1948
1949
1950Examples and applications
1951-------------------------
1952
1953- added methods to set and get hmin and hmax for optcumulative constraints
1954
1955Interface changes
1956-----------------
1957
1958### New and changed callbacks
1959
1960- new optional callback `SCIP_DECL_DIVESETAVAILABLE` to check preconditions for this dive set, e.g., if an incumbent solution is available,
1961 which is passed as new argument to SCIPcreateDiveset(). SCIPcreateDiveset() has another new parameter "ispublic".
1962
1963- new callback `SCIP_DECL_CONSHDLRCOPY` and `SCIP_DECL_CONSCOPY` in cons_orbisack and cons_symresack
1964
1965- new `idempotent` argument to SCIPgetVarStrongbranchInt() and SCIPgetVarStrongbranchFrac(),
1966 so that statistics are not updated during the call. Likewise, new `updatecol` and `updatestat` arguments to SCIPcolGetStrongbranch().
1967
1968- callback `SCIP_DECL_CONSHDLRENFOLP` can now also return SCIP_SOLVELP as *result, which indicates to the SCIP core that the LP relaxation
1969 should be solved again because the primal feasibility tolerance of the LP has been tightened (using SCIPsetLPFeastol())
1970
1971- extension of SCIP_PQUEUE by a new callback SCIP_DECL_PQUEUEELEMCHGPOS to catch swaps as well as functionality to delete arbitrary elements from the priority queue.
1972
1973### Deleted and changed API methods
1974
1975- LPI:
1976 + now for all lp interfaces consistent requirements on SCIP_LPPAR:
1977 LPITLIM and BARRIERCONVTOL positive or zero; FEASTOL, DUALFEASTOL, LPTILIM strictly positive
1978 + now projecting SCIP_LPPAR values on feasible values for each lp interface
1979 + add interface to Glop
1980 + fixed mapping between scaling parameter values in Gurobi LPI lpi_grb
1981- Symmetry:
1982 + removed method SCIPseparateCoversOrbisack() in cons_orbisack.h since the orbitope constraint
1983 handler has its own implementation of this routine with advanced features now
1984 + renamed SCIPgetGeneratorsSymmetry() to SCIPgetSymmetry() and removed two arguments
1985 + extended method SCIPgetSymmetry(): It is possible to access both the original and
1986 transposed permutations matrix as well as the (independent symmetry) components of a permutation group now.
1987 + arguments of functions SCIPcreateConsOrbisack(), SCIPcreateConsBasicOrbisack(), SCIPcreateConsOrbitope(),
1988 SCIPcreateConsBasicOrbitope(), SCIPcreateConsSymresack(), SCIPcreateConsBasicSymresack(), and SCIPcreateSymbreakCons() extended
1989 by "ismodelcons" to encode whether the constraints are model constraints or not
1990 + the function SCIPgetSymmetry() no longer accepts the parameter recompute, but has parameter permvarmap as new input
1991 + removed SCIPgetPermvarsObjSymmetry(), SCIPsetSymmetryComponentblocked(), SCIPgetSymmetryComponentblocked(),
1992 SCIPgetSyminfoGloballyFixedVars(), SCIPcomputeGroupOrbitsSymbreak, SCIPincludePresolSymmetry(),SCIPincludePresolSymbreak(),
1993 and SCIPincludePropOrbitalfixing()
1994 + add function SCIPcomputeOrbitsComponentsSym() to compute orbits without filtering permutations and indices of orbits for each variable
1995- SCIPallowObjProp() and SCIPallowDualReds() are deprecated and replaced by SCIPallowWeakDualReds() and SCIPallowStrongDualReds(), respectively
1996- Benders' decomposition
1997 + changed SCIPstoreBenderscutCut() in scip_benders.c to SCIPstoreBendersCut(). Where this function used to take a
1998 SCIP_BENDERSCUT pointer, it now accepts a SCIP_BENDERS pointer.
1999 + the functions SCIPsolveBendersSubproblem() no longer accepts the parameter type. The type is not a necessary
2000 argument for the subproblem solving method.
2001 + arguments of functions SCIPbendersSolveSubproblemLP(), SCIPbendersSolveSubproblemCIP(), and SCIPbendersOnlyCheckConvexRelax() changed
2002 - removed SCIPbenderscutGetNAddedCuts() and SCIPbenderscutGetAddedCutData()
2003
2004
2005### New API functions
2006
2007- new argument "onlyifcomplete" in SCIPmatrixCreate() to skip matrix creation right after detecting unsupported constraint types
2008 and new arguments to count statistics when doing a clean-up of inactive variables in the constraints before building the matrix
2009
2010- new argument "threadsafe" in SCIPcopy(), SCIPcopyConsCompression(), SCIPcopyOrig(), SCIPcopyOrigConsCompression and
2011 SCIPcopyBenders(). This argument must only be set to TRUE if the source and target SCIP instances are to be solved in
2012 parallel. Setting this argument to TRUE has a performance cost.
2013
2014- new argument "append" in SCIPsetModifiedDefaultSettingsIpopt()
2015- functions SCIPclearRelaxSolVals(), SCIPsetRelaxSolVal(), SCIPsetRelaxSolVals(), SCIPsetRelaxSolValsSol(), and SCIPmarkRelaxSolValid()
2016 receive an additional argument "relax" to store the relaxation handler as creator of the relaxation solution.
2017
2018- LP:
2019 - SCIProwGetOriginCons() now returns a SCIP_CONS* instead of a SCIP_CONSHDLR*, use SCIProwGetOriginConshdlr() for the previous behavior
2020 - SCIPcreateRowCons() and SCIPcreateEmptyRowCons() now expect a SCIP_CONS* instead of a SCIP_CONSHDLR*,
2021 use SCIPcreateRowConshdlr() and SCIPcreateEmptyRowConshdlr(), respectively, for the previous behavior
2022 - deprecated SCIPlpfeastol() and SCIPchgLpfeastol(), use SCIPgetLPFeastol() and SCIPsetLPFeastol()
2023
2024- new parameter "divecontext" for every method that queries statistics for a diveset. The context can be used to distinguish between the dive set
2025 as single (standalone) heuristic or within Adaptive Diving.
2026- new parameters "divecontext" and "iterlim" to SCIPperformGenericDivingAlgorithm() to control in which context (single,adaptive) statistics are updated.
2027
2028- SCIPcopyVars, SCIPcopy, SCIPcopyConsCompression, and SCIPgetVarCopy do not copy variables that are marked as relaxation-only,
2029 thus it cannot be assumed anymore that each active variable from the master SCIP also has a counterpart in the copy.
2030 SCIPcopy, SCIPcopyConsCompression, and SCIPcopyConss can now return *valid=TRUE if some non-checked and non-enforced constraints were not copied, e.g.,
2031 because they involved relaxation-only variables. Thus, a copy is already regarded as valid if all checked or enforced constraints were copied successfully.
2032
2033- linking constraint handler:
2034 - changed type of vals argument from int* to SCIP_Real* in SCIPcreateConsLinking() and SCIPcreateConsBasicLinking()
2035 - SCIPgetIntvarLinking() has been renamed to SCIPgetLinkvarLinking().
2036 - changed return value of SCIPgetValsLinking() from int* to SCIP_Real*.
2037 - new method SCIPgetBinvarsDataLinking().
2038
2039- SCIPbendersCheckSubproblemOptimality() now returns a boolean indicating whether the subproblem is optimal or not.
2040 Previously this result was returned through a parameter. The change was required to facilitate the integration with
2041 the UG framework.
2042
2043- deleted SCIPcombineTwoInt(), SCIPcombineThreeInt(), SCIPcombineFourInt(); use the appropriate SCIPhashTwo(), ..., SCIPhashSeven() method instead
2044
2045- SCIPsetupBendersSubproblem takes a parameter of the enforcement type.
2046
2047- SCIPcreateNlpiProb takes a hashmap to store the map between the nlrows and the index in the nlrow array.
2048
2049### New API functions
2050
2051- SCIPallowWeakDualReds() and SCIPallowStrongDualReds() replace the deprecated SCIPallowObjProp() and SCIPallowDualReds(), respectively
2052- methods have been added to facilitate the transfer of Benders' decomposition cuts between solvers in UG. These include
2053 SCIPapplyBendersStoredCuts(), SCIPbendersGetNStoredCuts(), SCIPbendersGetStoredCutData() and
2054 SCIPbendersGetStoredCutOrigData().
2055- added SCIPisConvexAbspower()
2056- new functions SCIPsolGetType(), SCIPsolGetRelax(), SCIPsolSetRelax(), SCIPsolSetLPRelaxation(), SCIPsolSetStrongbranch(),
2057 SCIPsolSetPseudo to set or query the new type attribute of a primal solution. The type attribute gives information
2058 about the origin of the solution, ie, whether it was created by a relaxation handler,
2059 by the LP relaxation, by strong branching, by the current pseudo solution, or by a primal heuristic.
2060 The meaning of the argument 'heur' in all creation methods for primal solutions such as SCIPcreateSol() stays unchanged.
2061- added SCIProwGetOriginConshdlr(), SCIPcreateRowConshdlr(), SCIPcreateEmptyRowConshdlr()
2062- new API functions SCIPsetCommonSubscipParams(), SCIPtranslateSubSol(), and SCIPtranslateSubSols() shared by several Large Neighborhood Search heuristics.
2063- new API function SCIPgetLPDualDegeneracy() to get two measures for the dual degeneracy of the current LP
2064- new API functions SCIPdivesetIsAvailable() to check preconditions of a dive set and SCIPdivesetIsPublic() to check if the dive set can be used
2065 by other primal heuristics.
2066- new API functions SCIPcomputeOrbitsSym(), SCIPcomputeOrbitsFilterSym(), SCIPgetPropertiesPerm(), SCIPdetermineBinvarAffectedSym(),
2067 SCIPdetermineNVarsAffectedSym(), SCIPcomputeComponentsSym(), and SCIPextendSubOrbitope(), SCIPgenerateOrbitopeVarsMatrix() for symmetry computations
2068- new API functions SCIPvarIsRelaxationOnly() and SCIPvarMarkRelaxationOnly() to query and set, resp., whether a variable is marked as relaxation-only
2069- new API functions SCIPconshdlrGetNUpdateConss() and SCIPconshdlrGetUpdateConss(), for expert users only
2070- new API function SCIPgetNConflictDualproofsApplied()
2071- new API functions SCIPeventGetOldtype() and SCIPeventGetNewtype() for the new event when changing the variable type
2072- new API function SCIPisConvexConsQuadratic() to check whether a quadratic constraint is convex when a given set of variables would be fixed
2073- new API functions SCIPgetLPFeastol(), SCIPsetLPFeastol(), and SCIPresetLPFeastol() to get, set, and reset (to the default), respectively, the primal
2074 feasibility tolerance for the LP relaxation
2075- new API functions SCIPcleanupConss{Linear,Varbound,Setppc,Logicor,Knapsack}() to clean up inactive variables from those types of linear constraints
2076- new API function SCIPsetBendersSubproblemComp() used to add a custom comparison method for ordering the Benders'
2077 decomposition subproblem solves. The comparison method is used to help with load balancing.
2078- new API function SCIPgetRowObjParallelism to get the objective parallelism of a row
2079- new API function SCIPcolGetAge to get the age of a column
2080- added SCIPhashThree(), SCIPhashFive(), SCIPhashSix(), and SCIPhashSeven() that complement SCIPhashTwo(), SCIPhashFour() to combine 32bit integers to
2081 a 32bit hash value
2082- new API function SCIPgenerateAndApplyBendersOptCut is used to generate a Benders' optimality cut using the dual
2083 solutions. This function can be supplied vectors for the primal and dual solution for generating an optimality cut.
2084 This avoids the need for a SCIP instance to solve the Benders' decomposition subproblem and generating cuts.
2085- new API function SCIPconsAddCoef used for adding a coefficient to a linear-type constraint.
2086- new API functions SCIPconsNonlinearGetRhs, SCIPconsNonlinearGetLhs and SCIPconsNonlinearAddLinearCoef for getting the
2087 RHS and LHS from a nonlinear-type constraint and adding a linear coefficient to the constraint.
2088- new API function SCIPbendersSolSlackVarsActive for checking whether any slack variables from the feasibility phase are
2089 active in the subproblem solution.
2090- new API functions SCIPbendersSetSubproblemType and SCIPbendersGetSubproblemType sets and gets the subproblem type.
2091 This is either:
2092 - Convex constraints with continuous variables
2093 - Convex constraints with discrete variables
2094 - Non-convex constraints with continuous variables
2095 - Non-convex constraints with discrete variables
2096- new API functions SCIPbendersSetSubproblemIsNonlinear() and SCIPbendersSubproblemIsNonlinear() for setting and
2097 identifying whether the Benders' decomposition subproblems contain nonlinear constraints. Similarly, the functions
2098 SCIPbendersSetMasterIsNonlinear() and SCIPbendersMasterIsNonlinear() sets and identifies whether the Benders'
2099 decomposition master problem contains nonlinear constraints.
2100- new API function SCIPapplyBendersDecomposition for applying Benders' decomposition given a decomposition in the DEC
2101 format
2102- new API function SCIPwasNodeLastBranchParent to query if a node has been the parent of the most recent branching in the tree
2103- new API functions SCIPtreemodelInit(), SCIPtreemodelFree(), SCIPtreemodelIsEnabled(), SCIPtreemodelSelectCandidate() related to the new
2104 treemodel way of comparing branching candidates. These functions are only currently used for reliability pscost branching, but they can be used
2105 in other parts of the code.
2106- New function SCIPcalcChildEstimateIncrease() to compute the increase in the child estimation
2107- new API functions SCIPisOrbitalfixingEnabled() and SCIPgetSymmetryNGenerators() to check whether orbital fixing is
2108 enabled and to get the number of generators of the current symmetry group, respectively
2109- new API function SCIPdelNlRow() to remove a row from the NLP
2110
2111### Event system
2112
2113- new event type SCIP_EVENTTYPE_NODEDELETE to react on nodes that are about to be deleted from the tree
2114
2115### Changed parameters
2116
2117- renamed parameter "propagating/orbitalfixing/enableafterrestart" to ".../symmetry/recomputerestart"
2118- Parameter "misc/allowdualreds" is now called "misc/allowstrongdualreds"
2119- Parameter "misc/allowobjprop" is now called "misc/allowweakdualreds"
2120- changed default values of propagation (new value: 1, old value: 5) and separation frequency (new value: -1, old value: 5) in cons_orbitope.c
2121- all primal heuristics that use sub-SCIPs are disabled within the heuristics fast emphasis setting
2122- deleted parameter heuristics/localbranching/useuct, use heuristics/useuctsubscip instead
2123- changed default value of "presolving/symbreak/detectorbitopes" (new value: TRUE, old value: FALSE)
2124- extended range of "misc/usesymmetry" (new range: [0,3], old range: [0,2])
2125- deleted parameter "constraints/orbisack/checkalwaysfeas"
2126- deleted parameter "constraints/orbitope/checkalwaysfeas"
2127- deleted parameter "constraints/symresack/checkalwaysfeas"
2128- deleted parameter "presolving/symmetry/maxgenerators"
2129- deleted parameter "presolving/symmetry/checksymmetries"
2130- deleted parameter "presolving/symmetry/displaynorbitvars"
2131- deleted parameter "presolving/symbreak/conssaddlp"
2132- deleted parameter "presolving/symbreak/addsymresacks"
2133- deleted parameter "presolving/symbreak/computeorbits"
2134- deleted parameter "presolving/symbreak/detectorbitopes"
2135- deleted parameter "presolving/symbreak/addconsstiming"
2136- deleted parameter "propagating/orbitalfixing/symcomptiming"
2137- deleted parameter "propagating/orbitalfixing/performpresolving"
2138- deleted parameter "propagating/orbitalfixing/recomputerestart"
2139- changed default value of "heuristics/coefdiving/freq" (old: 10, new: -1)
2140- changed default value of "heuristics/conflictdiving/freq" (old: -1, new: 10)
2141- changed default value of "heuristics/conflictdiving/lockweight" (old: 1.0, new: 0.75)
2142- replaced parameter "numerics/lpfeastol" by "numerics/lpfeastolfactor" to specify which factor should be applied to the SCIP feasibility
2143 tolerance to initialize the primal feasibility tolerance of the LP solver
2144- enabling aggressive presolving now activates all available presolving plugins,
2145 and decreases the presolving/restartfac parameter correctly with respect to default.
2146- changed default value of heuristics/rins/nodesquot to 0.3 (was 0.1), to compensate
2147 the removal of a hard coded factor of 3.0 in the code without affecting the default behavior
2148 of the RINS heuristic.
2149- changed default value of "constraints/quadratic/empathy4and" (old: 0, new: 2)
2150- changed default value of "propagating/redcost/useimplics" (old: TRUE, new: FALSE)
2151
2152### New parameters
2153
2154- the possibility to define the Benders' decomposition auxiliary variables as implicit integer is provided. This
2155 behavior is controlled with an additional parameter in the Benders' decomposition framework.
2156- added parameter benders/<bendersname>/cutcheck to enable the generation of Benders' decomposition cuts during solution
2157 checking.
2158- constraints/orbitope/usedynamicprop: the possibility to propagate orbitope constraints by reordering the rows based on the
2159 branching strategy is provided (only possible for non-model constraints)
2160
2161- new parameters heuristics/shiftandpropagate/minfixingratelp and heuristics/locks/minfixingratelp to stop the
2162 heuristics after propagating integer fixings if no sufficient fixing of the all variables (including continuous)
2163 could be achieved. These parameters help to avoid solving LP's that are comparable in hardness to the main root LP.
2164
2165- Added parameters branching/midpull and branching/midpullreldomtrig to control by how much to move
2166 the branching point for an external branching candidate closer to the middle of the candidates domain. The
2167 default of 0.75 and 0.5, respectively, uses a point that is 75*alpha% closer to the middle of the domain, where
2168 alpha is the relative width of the candidates domain (width of local domain divided by width of global domain),
2169 if the latter is below 0.5, and alpha=1.0 otherwise. That is, with the default settings, a branching point is
2170 chosen closer to the middle of the candidates domain if the variables local domain is still similar to its
2171 global domain, but is chosen closer to the LP solution if the local domain is much smaller than the global
2172 domain.
2173
2174- Added parameter lp/minmarkowitz to set the Markowitz stability threshold (range 0.0001 to 0.9999).
2175 High values sacrifice performance for stability.
2176
2177- Added parameters benders/<bendersname>/lnsmaxcalls and benders/<bendersname>/lnsmaxcallsroot to the Benders'
2178 decomposition core. These parameters limit the number of Benders' decomposition subproblem checks, for the full
2179 branch-and-bound tree and root node respective, when solving the auxiliary problem of LNS hueristics. These
2180 parameters only have effect if the lnscheck parameter is set to TRUE.
2181
2182- Added parameter cons/linear/maxmultaggrquot to limit the maximum coefficient dynamism of an equation on which
2183 multiaggregation is performed. This replaces a compiler define of the same name.
2184 Default value is 1000, smaller values make multiaggregations numerically more stable.
2185- new global parameter heuristics/useuctsubscip that affects all LNS heuristics using common sub-SCIP parameters
2186
2187- new parameter branching/relpscost/degeneracyaware to switch degeneracy-aware hybrid branching
2188
2189- new parameter separation/rapidlearning/checkexec to check whether rapid learning is allowed to run locally
2190- new parameters separation/rapidlearning/check{degeneracy,dualbound,leaves,nsols,obj} to enable checking the respective feature for local rapid learning
2191- new parameter separation/rapidlearning/maxcalls to limit the number of rapid learning executions
2192- new parameter separation/rapidlearning/nwaitingnodes to set the number of waiting nodes before the dual bound is checked
2193- new parameter separation/rapidlearning/mindegeneracy to set the minimal threshold of degenerate basic-variables
2194- new parameters separation/rapidlearning/minvarconsratio to set the minimal ratio of unfixed variables in relation to basis size
2195
2196- new parameters to control the Benders' decomposition two-phase method.
2197 - constraints/benderslp/depthfreq: after the maxdepth is reached, then the two-phase method will only be called at
2198 nodes at a depth divisible by depthfreq.
2199 - constraints/benderslp/stalllimit: after the maxdepth is reached, if there has been no improvement in the dual bound
2200 for stalllimit number of nodes, then the two-phase method is executed for the next fractional LP solution that is
2201 encountered.
2202 - constraints/benderslp/iterlimit: after the root node, only iterlimit fractional LP solutions are used at each node
2203 to generate Benders' decomposition cuts.
2204
2205- new parameters for symmetry handling
2206 - new parameter "propagating/symmetry/maxgenerators"
2207 - new parameter "propagating/symmetry/checksymmetries"
2208 - new parameter "propagating/symmetry/displaynorbitvars"
2209 - new parameter "propagating/symmetry/conssaddlp"
2210 - new parameter "propagating/symmetry/addsymresacks"
2211 - new parameter "propagating/symmetry/detectorbitopes"
2212 - new parameter "propagating/symmetry/addconsstiming"
2213 - new parameter "propagating/symmetry/ofsymcomptiming"
2214 - new parameter "propagating/symmetry/performpresolving"
2215 - new parameter "propagating/symmetry/recomputerestart"
2216 - new parameter "constraints/symresack/checkmonotonicity"
2217 - new parameter "propagating/symmetry/compresssymmetries"
2218 - new parameter "propagating/symmetry/compressthreshold"
2219 - new parameter "propagating/symmetry/disableofrestart"
2220 - new parameter "propagating/symmetry/symfixnonbinaryvars"
2221
2222- new parameter for enabling shared memory parallelisation for solving Benders' decomposition subproblems. The parameter
2223 benders/<bendersname>/numthreads sets the number of threads used for parallel subproblem solving.
2224
2225- new parameters to control enhancements for solving MINLPs by Benders' decomposition
2226 - benders/<bendersname>/execfeasphase: enables the feasibility phase for solving the Benders' decomposition
2227 subproblems
2228 - benders/<bendersname>/slackvarcoef: the initial coefficient of the slack variable for the feasibility phase
2229 - benders/<bendersname>/checkconsconvexity: should the constraints be checked for convexity. This can be set to FALSE
2230 if you are certain that the NLP subproblem is convex.
2231
2232- new parameter presolving/clqtablefac (default value 2.0) as limit on number of entries in clique table relative to number of problem nonzeros
2233
2234- new parameter conflict/uselocalrows (default: TRUE) to incorporate locally valid cuts / rows for dual proof analysis
2235
2236- new return code SCIP_NOTIMPLEMENTED for functions, e.g., in the LPI that have not been implemented (yet)
2237
2238- new parameter separating/cgmip/genprimalsols that allows to generate initial primal solutions from Gomory cuts
2239
2240- new parameter branching/relpscost/filtercandssym to allow filtering from orbits
2241
2242- new parameter branching/relpscost/transsympscost to transfer pseudo cost information to orbit
2243
2244- new parameters for tree size estimation and restarts:
2245 - estimation/restarts/restartpolicy (default value n)
2246 - estimation/method (default value c)
2247 - estimation/restarts/restartlimit (default value 1)
2248 - estimation/restarts/minnodes (default value 1000)
2249 - estimation/restarts/countonlyleaves (default value FALSE)
2250 - estimation/restarts/restartfactor (default value 2)
2251 - estimation/coefmonoprog (default value 0.3667)
2252 - estimation/coefmonossg (default value 0.6333)
2253 - estimation/restarts/hitcounterlim (default value 50)
2254 - estimation/reportfreq (default value -1)
2255 - estimation/regforestfilename (default value "-")
2256 - estimation/completiontype (default value a)
2257 - estimation/treeprofile/enabled (default value FALSE)
2258 - estimation/treeprofile/minnodesperdepth (default value 20)
2259 - estimation/useleafts (default value TRUE)
2260 - estimation/ssg/nmaxsubtrees (default value -1)
2261 - estimation/ssg/nminnodeslastsplit (default value 0)
2262
2263- new parameter constraints/linear/extractcliques to turn clique extraction off
2264
2265- new emphasis setting emphasis/numerics to increase numerical stability of (mostly) presolving operations such as (multi-)aggregations at the cost of performance.
2266
2267- new parameters for treemodel:
2268 - new parameter branching/treemodel/enable to enable the treemodel in reliability pscost branching and possible
2269 future parts of the code where it could be used.
2270 - new parameter branching/treemodel/highrule to specify which branching rule to use when treemodel thinks the node
2271 is high in the tree.
2272 - new parameter branching/treemodel/lowrule to specify which branching rule to use when treemodel thinks the node
2273 is low in the tree.
2274 - new parameter branching/treemodel/height to specify at which (estimated) height a node is high or low in the tree.
2275 - new parameter branching/treemodel/filterhigh to specify whether to filter dominated candidates in nodes which are
2276 high in the tree.
2277 - new parameter branching/treemodel/filterlow to specify whether to filter dominated candidates in nodes which are
2278 low in the tree.
2279 - new parameter branching/treemodel/maxfpiter to specify the maximum number of fixed-point iterations to use when
2280 computing the ratio of a variable using the fixed-point method.
2281 - new parameter branching/treemodel/maxsvtsheight to specify the maximum height to compute the SVTS score exactly
2282 before approximating it using the ratio.
2283 - new parameter branching/treemodel/fallbackinf defines the fallback strategy to use when the tree size estimates
2284 obtained by SVTS are infinite.
2285 - new parameter branching/treemodel/fallbacknoprim defines the fallback strategy to use when no primal bound is known
2286 and thus SVTS would not be able to compute a tree size (it would be infinite).
2287 - new parameter branching/treemodel/smallpscost defines the value under which pscosts are considered too small to be
2288 the deciding factor for branching, in which case it may be better not to use the treemodel.
2289
2290- new parameters for symmetry handling constraint handlers to enforce that also non-model constraint are copied:
2291 - new parameter "constraints/orbisack/forceconscopy"
2292 - new parameter "constraints/orbitope/forceconscopy"
2293 - new parameter "constraints/symresack/forceconscopy"
2294
2295
2296### Data structures
2297
2298- small changes in constants of hash functions
2299- added fast 2-universal hash functions for two to seven 32bit elements with 32bit output
2300- extended SCIPpqueueCreate() by additional callback argument SCIP_DECL_PQUEUEELEMCHGPOS to catch position changes
2301- new methods SCIPpqueueDelPos() to delete elements at a specific position in the priority queue and SCIPpqueueFind() to
2302 find a specific position. It is recommended to track position changes using the new callback SCIP_DECL_PQUEUEELEMCHGPOS.
2303 In contrast, using SCIPpqueueFind() can be slow because it needs to compare the element it searches for
2304 with each slot in the queue.
2305
2306### Build system
2307
2308- The default value for DFLAGS in the non-cmake buildsystem has changed from -MM to -MMD. This will break the
2309 generation of depend.* files if that was done by a compiler call that relied on -MM. The new preferred way
2310 to handle compilation dependencies is to additionally use $(DFLAGS) when compiling the object files (.o) and
2311 to include the generated .d files in the Makefile, see also "Build system / Makefile" below.
2312
2313Unit tests
2314----------
2315 - new unit test for treemodel.
2316
2317Testing
2318-------
2319
2320 - fixed an issue that may have lead to wrong status reports in the evaluation scripts
2321
2322Build system
2323------------
2324
2325### Cmake
2326
2327- avoid problem with doubly defined object together with CPLEX
2328
2329### Makefile
2330
2331- Removed static object compilation dependency files (depend.*). If using a GCC compatible compiler, then dependency
2332 files are now dynamically created and updated during build. The new dependency files (*.d) reside next to each object
2333 file (.o) in the corresponding obj subdirectory.
2334- added support for building against Ipopt >= 3.13
2335- unify compiler switches for Intel compiler and avoid problem with doubly defined object together with CPLEX
2336
2337Fixed bugs
2338----------
2339
2340- fix and improve memory handling in symmetry computation
2341- fix shown number of applied conflicts in solving statistics
2342- fix wrongly skipping strong branching call and using old information if LP was solved with 0 iterations
2343- fix minor bug in cut score calculation
2344- fixed several bugs related to rounding locks of variables not being updated correctly
2345- small fix in cons_varbound.c to skip changing bounds of multi-aggregated variables in separation callback
2346- fixed issue in SCIPtightenVar* and SCIPinferVar* that occurs for small bound changes
2347- fixed rejecting minimal boundchange that changed sign of variable, even though SCIPisLb/UbBetter approved it
2348- fixed issue in generateCutNonConvex() which is triggered when adding quadratic constraints during the solving process
2349- fixed bug in freeing the reoptimization data if no problem exists
2350- fixed bug in SCIPreoptReleaseData() when freeing all stored constraints
2351- fixed bug when freeing the transformed problem via interactive shell if reoptimization is enabled
2352- fixed two issues related to (near-)redundant logicor constraints in presolving
2353- fixed counting of aggregations in XOR constraint handler
2354- fixed handling of unbounded solutions
2355- fixed update of LP size information when an LP error occured during probing
2356- handle special case of variable bound constraints during aggregating variables
2357- tighten sides of linear constraints before trying to upgrade them to more specialized constraints (knapsack, logic-or etc.) when calling SCIPupgradeConsLinear()
2358- fixed an issue in repair heuristic in the case of loose (noncolumn) variables
2359- allow user to correctly set heuristics/alns/(un)fixtol
2360- fixed an issue in heur_completesol which is triggered during bound widening of unbounded continuous variables
2361- fixed bug in cons_indicator if addopposite is true
2362- fixed bug in sepa_disjunctive: treat case that conflictgraph is empty
2363- added safety check in conversion to rational number to avoid overflow
2364- fixed bug in interval evaluation with power-operator in certain situations
2365- fixed behavior of SCIPmatrixCreate() regarding memory management and column generation
2366- SCIPmatrixCreate() returns complete=FALSE when locks do not add up
2367- fixed bug in sepa_oddcylce when variables are fixed
2368- fixed numerical issues related to tighter constraint sides in varbound constraint handler
2369- fixed update of watchedvars in logicor constraint handler in case of a restart during the tree
2370- fixed treatment of multi-aggregated variables in logicor constraint handler
2371- handle special case of redundant implications
2372- fixed numerical issue related to almost-0-values in pseudosolution conflict analysis
2373- fixed numerical issue related to very large greatest common dividers in linear constraint handler
2374- avoid using implications on multiaggregated variables when propagating implications
2375- fixed creation of (Lagrangian) variable bounds in the OBBT propagator
2376- fixed sorting of primal solutions
2377- fixed cleaning of clean buffer in conflict analysis
2378- avoid probing on variables with huge bounds in shift and propagate heuristic
2379- fix issue in printing solutions for variables that have been added by the dual sparsify presolver
2380- fix issue related to fixing redundant logic-or constraints after presolving
2381- fixed bug when parsing logic-or and and-constraints
2382- fixed wrong assert in updateLazyBounds()
2383- fixed bug in pricestore, which resulted in too many problem variables being added
2384- fixed bug in cons_knapsack where weight of clique was not reset after an infeasibility was detected
2385- fixed bug in presol_inttobinary which did not take into account that the aggregation could be rejected due to numerics
2386- fixed bug in debug solution mechanism in connection to variables created by presol_inttobinary
2387- fixed wrong indexing while undoing the implications from a redundant variable in SCIPshrinkDisjunctiveVarSet
2388- redundancy checks in SCIPnodeAddBoundinfer now take a possible change to an active variable into account
2389- fixed adding already added quadratic rows to NLP relaxation during solve
2390- fixed issue related to variable locks in the varbound constraint handler
2391- fixed bug in the quadratic constraint handler when changing infinite constraint sides
2392- fixed sorting of variables in linear constraint handler
2393- added additional checks to ensure numerical stability of dual proofs
2394- fixed a case when activities of a linear constraint got unreliable but where still used for reductions
2395- ensure that lhs <= rhs for linear constraints (without tolerances)
2396- make handling of read errors in SCIPfread() consistent between version with and without ZLIB
2397- correctly drop variable events in cons_indicator in restart
2398- fixed bug in cons_orbitope with upgrading of orbitope constraints
2399- additional checks in some presolvers for time limit being exceeded
2400- fixed bug in presolving of cons_varbound with multi-aggregated variables
2401- improve numerics in conflict analysis by using double-double arithmetic
2402- fixed bound acceptance condition to avoid inconsistencies
2403- fixed numerics in pseudoobj propagator by using double-double arithmetic
2404
2405Miscellaneous
2406-------------
2407
2408- modified display column for memory usage ("mem"), which reports the memory usage most of the time, but shows the creator name
2409 (heuristic, relaxation handler, LP relaxation, strong branching, pseudo solution) of every new incumbent solution. Together with this change,
2410 heuristic display characters have been unified to represent the type of the heuristic
2411 (diving, Large neighborhood search, propagation, etc.), see also type_heur.h.
2412- added assert that ensures that the locks of a variable have been decreased to 0 when it is freed
2413- added more output for completing a partial solution
2414- checks in debug mode that clean buffer memory is really clean when being freed are now disabled by default
2415- don't compute symmetries if reoptimization is enabled
2416- prefer integral values when fixing an almost-fixed continuous variable in the trivial presolver
2417- changed the name of the variable that is added by the OSiL reader to represent the quadratic or nonlinear parts of the objective function
2418- SCIP_EXPORT is now defined as __attribute__((__visibility__("default"))) if GCC and no SCIP config header is used
2419
2420@page RN60 Release notes for SCIP 6.0
2421
2422@section RN602 SCIP 6.0.2
2423*************************
2424
2425Features
2426--------
2427
2428- The abspower constraint handler now passes more accurate convexity
2429 information to the NLP relaxation.
2430
2431Examples and applications
2432-------------------------
2433
2434- added parsing functionality for optcumulative constraints in CIP format
2435
2436Interface changes
2437-----------------
2438
2439### Interfaces to external software
2440
2441- Updated the Mosek LP solver interface to support Mosek 9.0.
2442
2443Build system
2444------------
2445
2446### Cmake
2447
2448- new target to 'doc' to build documentation
2449- ctests now fail if parameter file not found
2450- add flag STATIC_GMP and improve GMP find module
2451- remove non-API methods from library (API methods use new macro SCIP_EXPORT)
2452- increase minimal required CMake version to 3.3
2453- correct paths and dependency information when installing SCIP
2454
2455Fixed bugs
2456----------
2457- fixed SCIP-Jack presolving bug that could lead to wrong results for Steiner arborescence problems
2458- fixed wrong unboundedness result in case not all constraints were already in the LP and enforcement was
2459 skipped because an optimal solution was found
2460- fixed wrong enforcement of constraints in the disjunction constraint handler
2461- fixed wrong behavior of concurrent solve ignoring initial solutions
2462- fixed bug in concurrent solve when problem was already solved in presolving
2463- aggregate non-artificial integer variable for XOR constraints with two binary variables and delete constraint
2464- copy the objective offset when copying the original problem
2465- fixed bug in SCIPlpiGetBInvARow in lpi_cpx using wrong size of resulting vector
2466- fixed quadratic runtime behavior in sepa_aggregation
2467- fixed statistics of separators
2468- improve numerical stability in varbound constraint handler by using double-double arithmetic
2469- fixed bug in propagation of dual proofs
2470- fixed bugs that arise for multiaggregated indicator variables by disallowing multiaggregation for them
2471- improve numerical stability in SCIPcomputeBilinEnvelope* by using double-double arithmetic
2472- fixed bug related to releasing pending bound changes in tree.c
2473- set STD FENV_ACCESS pragma to on in code that changes floating-point rounding mode
2474- disable GCC optimizations in main interval arithmetic code to prevent wrong optimizations
2475- fixed wrong assert in cons_xor concerning the variable type
2476- fixed different behavior of SCIPisLbBetter and SCIPisUbBetter between having NDEBUG defined or not
2477- correctly handle bound disjunctions in symmetry detection
2478- fixed issue in reliability branching related to the LP error flag not being reset
2479- fixed treatment of near-infinite bounds in shiftandpropagate's problem transformation
2480- fixed handling of infinite values in SCIPcomputeHyperplaneThreePoints()
2481- fixed comparisons of infinite values in heur_intshifting.c and heur_shifting.c
2482- fixed bug related to updating unprocessed cuts in the cutpool
2483- fixed bug related to enabling quadratic constraints during `CONSINITLP`
2484- add missing SCIP_EXPORT for functions used by GCG
2485- fixed memory leak and wrong initialization for trival cases in cons_symresack.c
2486- fixed bug with upgrading to packing/partitioning orbitopes
2487- fixed bug with the status while upgrading in presol_symbreak.c
2488- fixed wrong stage while clearing the conflict store
2489- fixed behavior of SCIPfixVar() by setting infeasible pointer to TRUE if fixval lies outside variable domain
2490- allow tightenVar() in SCIP_STAGE_PROBLEM stage
2491- fixed bug in cumulative constraint handler when separating the LP solution
2492- fixed issues with integer overflow in cumulative constraint handler
2493- fixed bug where the convexity of Benders' decomposition subproblems was checked even when users defined subproblem
2494 solving methods. Now, as per the documentation, the user must explicitly state whether the subproblem is convex
2495- fixed wrong indexing in heur_dualval
2496- fixed issue with basis status in SoPlex LPi
2497
2498Miscellaneous
2499-------------
2500
2501- statistics now output primal/dual bounds if objective limit is reached
2502- memory check in debug mode is now disabled by default
2503- message is now provided to the user to inform that automatic Benders' auxiliary variable lower bound computations are
2504 not activated when user defined subproblem solving methods are present
2505- corrected documentation of the primalgap in SCIP; describe when it will be infinite
2506
2507@section RN601 SCIP 6.0.1
2508*************************
2509
2510Features
2511--------
2512
2513- when using a debug solution every (multi-)aggregation will be checked w.r.t. this solution
2514
2515Performance improvements
2516------------------------
2517
2518- try greedy solution first before solving knapsack exactly using dynamic programming in SCIPsolveKnapsackExactly,
2519 compute greedy solution by weighted median selection.
2520- don't consider implied redcost by default in the reduced cost propagator
2521
2522Interface changes
2523-----------------
2524
2525### Deleted and changed API methods and macros
2526
2527- The preprocessor macro NO_CONFIG_HEADER now needs to be defined when
2528 including SCIP header files from a SCIP build or installation that
2529 has been build via the Makefile-only build system.
2530
2531- The following preprocessor macros have been renamed:
2532 WITH_ZLIB to SCIP_WITH_ZLIB, WITH_GMP to SCIP_WITH_GMP, WITH_READLINE
2533 to SCIP_WITH_READLINE, NO_SIGACTION to SCIP_NO_SIGACTION, NO_STRTOK_R
2534 to SCIP_NO_STRTOK_R, ROUNDING_FE to SCIP_ROUNDING_FE, ROUNDING_FP to
2535 SCIP_ROUNDING_FP, ROUNDING_MS to SCIP_ROUNDING_MS. Note, however, that
2536 the names of macros NO_RAND_R and NO_STRERROR_R have not been changed
2537 so far.
2538
2539### New API functions
2540
2541- SCIPhashmapInsertInt(), SCIPhashmapSetImageInt(), and SCIPhashmapGetImageInt() to use integer values as images in hashmaps
2542
2543### Command line interface
2544
2545- warn about coefficients in MPS files with absolute value larger than SCIP's value for infinity
2546
2547### Changed parameters
2548
2549- default clock type for timing is now wallclock
2550
2551Unit tests
2552----------
2553
2554- added unit tests for exact knapsack solving and (weighted) median selection algorithms
2555
2556Build system
2557------------
2558
2559### Cmake
2560
2561- add missing GMP dependency when compiling with SYM=bliss
2562- add DL library when linking to CPLEX to avoid linker errors
2563- new config.h header defining the current build configuration, e.g. SCIP_WITH_GMP
2564
2565Fixed bugs
2566----------
2567
2568- fixed handling of weights in cons_sos1 and cons_sos2 (NULL pointer to weights)
2569- fixed handling of unbounded LPs in SCIP and in several LPIs; added heuristic method to guess solution
2570- the STO reader is capable of handling scenarios defined using lower case "rhs"
2571- fixed OPB reader for instances without explicit plus signs
2572- correct dual solution values for bound constraints
2573- fixed recognition of variable with only one lock in cons_bivariate, cons_quadratic, and cons_nonlinear
2574- fixed update of constraint violations in solution repair in cons_bivariate, cons_quadratic, and cons_nonlinear
2575- print error message and terminate if matrix entries of a column are not consecutive in mps format
2576- fixed incorrect handling of fixed variables when transfer of cuts from LNS heuristic for Benders' decomposition
2577- fix returning local infeasible status by Ipopt interface if Ipopt finds problem locally infeasible
2578- skip attempt to apply fixings in linear constraint handler during solving stage as LP rows cannot change anymore
2579- fixed bug when reading >= indicator constraints in MPS format
2580- fix issue with nodes without domain changes if we ran into solution limit in prop_orbitalfixing
2581- fixed unresolved reference to CppAD's microsoft_timer() function on builds with MS/Intel compilers on Windows
2582- ignore implications added through SCIPaddVarImplication() that are redundant to global bounds also in the
2583 special case of an implication between two binary variables; also, use implications instead of cliques in the case
2584 of a binary implied variable with nonbinary active representative
2585- fixed bug with aggregated variables that are aggregated in propagation of cons_sos1
2586- fixed some special cases in SCIPselect/SCIPselectWeighted methods
2587- relaxed too strict assertion in Zirounding heuristic
2588- fixed the upgrade routine to XOR constraints: aggregate integer variable if its coefficient has the wrong sign
2589- fixed handling of nonartificial parity variables when deleting redundant XOR constraints
2590- earlier deletion of trivial XOR constraints (at most 1 operator left)
2591- fixed wrong hashmap accesses and added sanity check for the correct hashmap type
2592- avoid copying of unbounded solutions from sub-SCIPs as those cannot be checked completely
2593- corrected the output of the first LP value in case of branch-and-price
2594- fixed possible integer overflow, which led to wrong conclusion of infeasibility, in energetic reasoning of cons_cumulative.c
2595
2596Miscellaneous
2597-------------
2598
2599- do not scale linear constraints to integral coefficients
2600
2601@section RN600 SCIP 6.0.0
2602*************************
2603
2604Features
2605--------
2606
2607- new diving heuristic farkasdiving that dives into the direction of the pseudosolution and tries to construct Farkas-proofs
2608- new diving heuristic conflictdiving that considers locks from conflict constraints
2609- restructuring of timing of symmetry computation that allows to add symmetry handling components within presolving
2610- `lp/checkstability` is properly implemented for SoPlex LPI (spx2)
2611- new branching rule lookahead that evaluates potential child and grandchild nodes to determine a branching decision
2612- limits on the number of presolving rounds a presolver (maxrounds) or propagator/constraint handler (maxprerounds)
2613 participates in are now compared to the number of calls of the particular presolving method, not the number of
2614 presolving rounds in general, anymore
2615- new miscellaneous methods for constraints that have a one-row linear representation in pub_misc_linear.h
2616- a Benders' decomposition framework has been added. This framework provides the functionality for a user to solve a
2617 decomposed problem using Benders' decomposition. The framework includes classical optimality and feasibility cuts,
2618 integer optimality cuts and no-good cuts.
2619- add statistic that presents the number of resolves for instable LPs
2620- new readers for stochastic programming problems in SMPS format (reader_sto.h, reader_smps.h)
2621
2622Performance improvements
2623------------------------
2624
2625- cuts generated from certain quadratic constraints with convex feasible region are now global
2626- performance improvements for Adaptive Large Neighborhood Search heur_alns.c
2627 + all neighborhoods now start conservatively from maximum fixing rate
2628 + new default parameter settings for bandit selection parameters
2629 + no adjustment of minimum improvement by default
2630- improved bound tightening for some quadratic equations
2631- constraint handler checking order for original solutions has been modified to check those with negative check priority
2632 that don't need constraints after all other constraint handlers and constraints have been checked
2633- deactivate gauge cuts
2634
2635Examples and applications
2636-------------------------
2637
2638- new example `brachistochrone` in CallableLibrary examples collection; this example implements a discretized model to
2639 obtain the trajectory associated with the shortest time to go from point A to B for a particle under gravity only
2640- new example `circlepacking` in CallableLibrary examples collection; this example models two problems about packing
2641 circles of given radii into a rectangle
2642- new price-and-branch application for the ringpacking problem
2643- new stochastic capacitated facility location example demonstrating the use of the Benders' decomposition framework
2644
2645Interface changes
2646-----------------
2647
2648### New and changed callbacks
2649
2650- added parameter locktype to `SCIP_DECL_CONSLOCK` callback to indicate the type of variable locks
2651
2652### Deleted and changed API methods
2653
2654- Symmetry:
2655 + removed function SCIPgetTimingSymmetry() in presol_symmetry.h since this presolver does not compute symmetries independent
2656 of other components anymore
2657 + additional argument `recompute` to SCIPgetGeneratorsSymmetry() to allow recomputation of symmetries
2658
2659- Random generators:
2660 + the seed of SCIPinitializeRandomSeed() is now an unsigned int
2661 + the seed of SCIPsetInitializeRandomSeed() is now an unsigned int and it returns an unsigned int
2662 + new parameter for SCIPcreateRandom() to specify whether the global random seed shift should be used in the creation of
2663 the random number generator
2664
2665- Miscellaneous:
2666 + additional arguments `preferrecent`, `decayfactor` and `avglim` to SCIPcreateBanditEpsgreedy() to choose between
2667 weights that are simple averages or higher weights for more recent observations (the previous default).
2668 The last two parameters are used for a finer control of the exponential decay.
2669 + functions SCIPintervalSolveUnivariateQuadExpression(), SCIPintervalSolveUnivariateQuadExpressionPositive(), and
2670 SCIPintervalSolveUnivariateQuadExpressionPositiveAllScalar() now take an additional argument to specify already
2671 existing bounds on x, providing an entire interval ([-infinity,infinity]) gives previous behavior
2672
2673### New API functions
2674
2675- SCIPintervalSolveUnivariateQuadExpressionNegative()
2676- SCIPvarGetNLocksDownType() and SCIPvarGetNLocksUpType()
2677- SCIPaddConsLocksType()
2678- SCIPconsIsLockedTypePos(), SCIPconsIsLockedTypeNeg(), SCIPconsIsLockedType(), SCIPconsGetNLocksTypePos() and SCIPconsGetNLocksTypeNeg()
2679- SCIPstrncpy(), a safe version of strncpy()
2680
2681### Changed parameters
2682
2683- Removed parameters:
2684 - `heuristics/alns/stallnodefactor` as the stall nodes are now controlled directly by the target node limit within the heuristic
2685 - `presolving/symmetry/computepresolved` since this presolver does not compute symmetries independent of other components anymore
2686 - `separating/maxincrounds`
2687
2688### New parameters
2689
2690- `lp/checkfarkas` that enables the check of infeasibility proofs from the LP
2691- `heuristics/alns/unfixtol` to specify tolerance to exceed the target fixing rate before unfixing variables, (default: 0.1)
2692- `propagating/orbitalfixing/symcomptiming` to change the timining of symmetry computation for orbital fixing
2693- `lp/alwaysgetduals` ensure that the dual solutions are always computed from the recent LP solve
2694- `display/relevantstats` indicates whether the small relevant statistics are displayed at the end of solving
2695- `propagating/orbitalfixing/performpresolving` that enables orbital fixing in presolving
2696- `presolving/symbreak/addconsstiming` to change the timining of symmetry computation for symmetry handling inequalities
2697- `propagating/orbitalfixing/enabledafterrestarts` to control whether orbital fixing is enabled after restarts
2698- `benders/∗` new submenu for Benders' decomposition related settings. This includes the settings related to the
2699 included Benders' decompositions and the general Benders' decomposition settings.
2700- `benders/<decompname>/benderscuts/∗` submenu within each included Benders' decomposition to control the Benders'
2701 decomposition cuts. The cuts are added to each decomposition separately, so the setting are unique to each
2702 decomposition.
2703
2704### Data structures
2705
2706- new enum `SCIP_LOCKTYPE` to distinguish between variable locks implied by model (check) constraints (`SCIP_LOCKYPE_MODEL`)
2707 and variable locks implied by conflict constraints (`SCIP_LOCKYPE_CONFLICT`)
2708- expression interpreter objects are now stored in the block memory
2709
2710Deleted files
2711-------------
2712
2713- removed presolving plugin presol_implfree
2714- separated scip.c into several smaller implementation files scip_*.c for better code overview; scip.c was removed,
2715 but the central user header scip.h remains, which contains includes of the separated headers
2716
2717Fixed bugs
2718----------
2719
2720- fixed bug in gcd reductions of cons_linear regarding an outdated flag for variable types
2721- fixed bug in heur_dualval regarding fixing routine for integer variables
2722- suppress debug solution warnings during problem creation stage
2723- fixed check for activated debugging solution in components constraint handler
2724- fixed potential bug concerning solution linking to LP in SCIPperformGenericDivingAlgorithm()
2725- fixed reward computation in ALNS on continuous, especially nonlinear, problems
2726- fixed bug in freeing reoptimization data if problem was solved during presolving
2727- fixed check of timing in heur_completesol
2728- fixed wrong propagation in optcumulative constraint handler
2729- fixed non-deterministic behavior in OBBT propagator
2730- don't disable LP presolving when using Xpress as LP solver
2731- fixed possible `NULL` pointer usage in cons_pseudoboolean
2732- ensured that SCIPgetDualbound() returns global dual bound instead of the dual bound of the remaining search tree
2733- fixed rare division-by-zero when solving bivariate quadratic interval equation
2734- use total memory for triggering memory saving mode
2735- fix parsing of version number in the CMake module for Ipopt
2736- fixed handling of implicit integer variables when attempting to solve sub-MIP in nlpdiving heuristic
2737- added workaround for bug when solving certain bivariate quadratic interval equations with unbounded second variable
2738- fixed bug with releasing slack variable and linear constraint in cons_indicator
2739- fixed problem when writing MPS file with indicator constraints with corresponding empty linear constraints
2740- fixed bug in heur_vbound triggered when new variables were added while constructing the LP
2741- fixed bug with unlinked columns in SCIProwGetLPSolCutoffDistance()
2742
2743Miscellaneous
2744-------------
2745
2746- updated CppAD to version 20180000.0
2747- remove LEGACY mode, compiler needs to be C++11-compliant
2748
2749@page RN50 Release notes for SCIP 5.0
2750
2751@section RN501 SCIP 5.0.1
2752*************************
2753
2754Features
2755--------
2756
2757- SCIP executable handles the `SIGTERM` signal. If the process receives a `SIGTERM`, SCIP terminates the solution process with a
2758 new `SCIP_STATUS` code `SCIP_STATUS_TERMINATE` and displays all relevant statistics before exiting.
2759- add number of conflict constraints found by diving heuristics to statistics
2760- allow output of lower bounds for visualization
2761- added symmetry detection for linking constraints
2762
2763Performance improvements
2764------------------------
2765
2766- disable disaggregation of quadratic constraints by changing the default for `constraints/quadratic/maxdisaggrsize` to 1
2767 (disaggregation can still be very helpful on some instances, but also seems hurtful on others)
2768
2769- Cuts:
2770 - increased threshold when to scale up cuts that are generated by nonlinear constraint handlers
2771 - test additional scaling factors in CMIR cut generation heuristic
2772 - cleaned up implementation of the cut selection procedure and added new cut quality measure
2773 - use random tie-breaking in cut selection
2774
2775Interface changes
2776-----------------
2777
2778### New API functions
2779
2780- new methods SCIPtryTerminate() and SCIPterminated() in scip/interrupt.h for handling of SIGTERM signals.
2781- new method SCIPselectCuts() to run SCIP's cut selection procedure on a given array of cuts
2782
2783### Changed parameters
2784
2785- rename parameter `constraints/orbisack/orbisack/coverseparation` to `constraints/orbisack/coverseparation`
2786
2787### New parameters
2788
2789- `visual/displb` that enables output of lower bounds for visualization
2790- `presolving/symmetry/displaynorbitvars` (whether we display the number of affected variables in the statistics)
2791- `separating/efficacyfac` to change the weight of the efficacy in cut score calculation
2792- `separating/dircutoffdistfac` to change the weight of the directed cutoff distance in cut score calculation
2793
2794### Data structures
2795
2796- new `SCIP_STATUS` code `SCIP_STATUS_TERMINATE` in scip/interrupt.h for handling of SIGTERM signals.
2797
2798Unit tests
2799----------
2800
2801- expanded unit tests of the lpis
2802- added check to unit tests that problem is not solved after every change
2803
2804Fixed bugs
2805----------
2806
2807- fixed LP status to unsolved when marking LP to be resolved if objective limit has changed
2808- copy parameter settings to sub-SCIPs in SCIPcopyLargeNeighborhoodSearch() also when copying only LP rows
2809- fixed a check for fixed variables in Binpacking example
2810- generate deprecation warnings when using SCIPaddCut
2811- fix bug in sepa_gomory if cut is a bound change
2812- fixed handling of infinite bounds in cons_sos1
2813
2814- Constraints:
2815 - fixed bug while scaling linear constraints
2816 - don't delete conflict constraints that were transformed into model constraints during a restart
2817 - fixed treatment of variable aggregations in knapsack constraint handler that led to wrong propagations
2818
2819- LP Interface:
2820 - fixed LPI status after changing objective in lpi_cpx, lpi_grb, lpi_xprs, lpi_msk
2821 - fixed and unified asserts in LPIs
2822 - retrieve interior solution instead of (possibly non-existing) basic solution from mosek after using barrier without crossover in lpi_msk
2823 - fixed bug with `NULL` pointer handling in LPIs
2824
2825- Heuristics:
2826 - fixed wrong cast in LP iteration limit computation in proximity search heuristic
2827 - fixed check for time limit in heur_nlpdiving
2828 - improved numerics and fixed stop criterion in zirounding heuristic
2829
2830@section RN500 SCIP 5.0.0
2831*************************
2832
2833Features
2834--------
2835
2836- new numerical solution violations get printed when checksol is called
2837- added analysis of the clique table which identifies possible aggregations via the search for
2838 strongly connected components and may detect infeasible assignments on the way
2839- added macros to do computations with a higher precision by using double-double arithmetic
2840- extended conflict analysis by analyzing dual solutions of boundexceeding LPs
2841- revised internal debugging mechanism to check against a user given debug solution (debug.h)
2842
2843- Heuristic:
2844 - add new heuristic MPEC that solves a MPEC reformulation of a mixed-binary nonlinear problem by regularized NLP reformulations
2845 - new primal heuristic ALNS that orchestrates eight different LNS heuristics adaptively
2846 using algorithms for the multi-armed bandit problem
2847 - three bandit selection algorithms to face sequential decision problems under uncertainty
2848
2849- Presolving and symmetry:
2850 - added presol_symmetry.c for computing and storing symmetry information of a MIP
2851 - added presol_symbreak.c to detect special symmetry structures and to add symmetry handling constraints
2852 - SCIP can now automatically detect and compute symmetries in MIPs (if a graph automorphism code is linked in)
2853 - added cons_symresack.c to handle permutation symmetries in a binary programs via inequalities and propagation
2854 - added cons_orbisack.c to handle special permutation symmetries in a binary programs via inequalities and propagation
2855 - cons_orbitope.c can now handle full orbitopes as well
2856
2857- Propagator:
2858 - added new propagator orbital fixing
2859 - utilizing linear inequalities to compute stronger linearizations for bilinear terms; the inequalities are computed in
2860 the OBBT propagator
2861
2862- Cuts:
2863 - added API for aggregating rows for generating cuts which uses double-double arithmetic internally
2864 - added filtering of parallel cuts in the cut pool
2865
2866- Plugins:
2867 + added new plugin type `table` for adding user-defined statistics tables
2868 + new presolving plugin presol_sparsify that tries to cancel nonzero coefficients in linear constraints by adding
2869 multiples of linear equalities
2870
2871Performance improvements
2872------------------------
2873
2874- use disjoint set to reduce peak memory usage and time to compute of clique table connectedness information
2875- add and use RESTRICT macro for some pointers
2876- improved the implementation of SCIPvarGetActiveRepresentatives
2877- speed-up reverse propagation
2878- removed bestrelaxsol and directly access relaxation solution instead to decrease overhead when using relaxation handlers
2879- for fast presolving emphasis, disable use of implications in logicor presolving
2880- use limit on the total number of nonzeros added to the clique table during the greedyCliqueAlgorithm of cons_knapsack.c
2881- revised disaggregation of quadratic constraints: the number of created constraints can now be controlled and the
2882 disaggregated constraints are scaled in order to increase numerical accuracy
2883- disabled reformulation of products of a binary variable with a linear term that does not solely involve binary variables
2884- speed up creation of LP in the computation of relative interior points
2885- improved dual ray analysis
2886- drop events of disabled linear constraints to reduce event processing effort
2887
2888- Separation:
2889 - new implementation of zerohalf separator
2890 - enabled cutting plane separation in the tree
2891 - improved cut selection and management
2892 - improved cut post-processing: apply coefficient tightening, enforce maximal dynamism
2893
2894- Heuristics:
2895 - improved selection of rows in CMIR aggregation heuristic
2896 - generate lifted flowcover cuts in CMIR cut generation heuristic
2897 - faster implementation of CMIR cut generation heuristic
2898 - use LP solution polishing during probing and diving mode to activate it during many primal heuristics; remains disabled
2899 during strong branching and OBBT
2900 - improved versions of the clique and variable bound pre-root heuristics that are often able to fix many more variables
2901
2902Interface changes
2903-----------------
2904
2905### New and changed callbacks
2906
2907- New types:
2908 - added new abstract selection algorithm `SCIP_BANDIT` together with callbacks
2909 - added new types for symmetry handling
2910
2911- NLP interface:
2912 - dropped NLP termination status `SCIP_NLPTERMSTAT_UOBJLIM`
2913
2914- NLP callbacks:
2915 - added parameter `objval` to `SCIP_DECL_NLPIGETSOLUTION` for returning the optimal objective value (can be set to `NULL`)
2916
2917- Separation callbacks:
2918 - added parameter `allowlocal` to `SCIP_DECL_SEPAEXECLP` and `SCIP_DECL_SEPAEXECSOL` to switch generation of locally valid cuts
2919 - added parameter `dstatssize` to `SCIP_DECL_NLPIDELVARSET` and `SCIP_DECL_NLPIDELCONSSET`
2920
2921### Deleted and changed API methods
2922
2923- Branching rules:
2924 - removed parameter `allowaddcons` from SCIPselectVarPseudoStrongBranching(), SCIPselectVarStrongBranching(), and
2925 SCIPincludeBranchruleRelpscost()
2926
2927- Constraint Handlers:
2928 - generalized SCIPcreateConsOrbitope() and SCIPcreateConsBasicOrbitope() method to three orbitope types (full, partitioning, packing)
2929
2930- Cutting plane separation methods:
2931 - changed function signature of SCIPcalcMIR()
2932 - changed function signature of SCIPcalcStrongCG()
2933 - new method SCIPaddRow() to replace deprecated SCIPaddCut()
2934 - removed parameter `scaling` from SCIPgetRowprepViolation()
2935 - added parameter `allowlocal` to SCIPseparateSol()
2936
2937- LP interface:
2938 - replaced LP parameters `SCIP_LPPARAM_LOBJLIM` and `SCIP_LPPARAM_UOBJLIM` by `SCIP_LPPARAM_OBJLIM`
2939
2940- NLP interface:
2941 - SCIPnlpStatisticsCreate() and SCIPnlpStatisticsFree() now require a pointer to blockmemory as parameter
2942 - added parameter `objval` to SCIPnlpiGetSolution() of NLPIs for returning the optimal objective value (can be set to `NULL`)
2943 - added parameter `varnameslength` to SCIPexprParse()
2944 - added parameter `dstatssize` to SCIPnlpiDelVarSet() and SCIPnlpiDelConsSet()
2945 - added modifier const to `exprtree` parameter of SCIPnlpiChgExprtree()
2946
2947- Primal heuristics:
2948 - SCIPheurPassIndicator() has a new parameter which allows to pass the objective of the solution
2949
2950- Relaxator methods:
2951 - added parameter `includeslp` to SCIPmarkRelaxSolValid(), SCIPsetRelaxSolVals() and SCIPsetRelaxSolValsSol();
2952 - removed parameter `includeslp` from SCIPrelaxCreate() and SCIPincludeRelax()
2953 - removed functions SCIPrelaxIncludesLp() and SCIPrelaxSetIncludesLp()
2954 - replaced method SCIPgetRelaxFeastolFactor() by SCIPrelaxfeastol() and added SCIPchgRelaxfeastol()
2955
2956- Misc:
2957 - changed return type of SCIPcliqueGetId() from `int` to `unsigned int`
2958 - SCIPsolveParallel() is deprecated; use SCIPsolveConcurrent() instead
2959 - removed SCIPvarGetCliqueComponentIdx(); the connectedness information of the clique table is now stored as a
2960 `SCIP_DISJOINTSET` member of the clique table and cannot be publicly accessed
2961 - added parameter `copytables` to SCIPcopyPlugins()
2962 - SCIPsolveParallel() has been deprecated, use the new method SCIPsolveConcurrent() instead
2963 - allowed SCIPgetNConss() in stage `SCIP_STAGE_INITSOLVE`
2964
2965### New API functions
2966
2967- SCIPaddRow() to replace deprecated SCIPaddCut()
2968- methods to display linear constraint classification types; use SCIPclassifyConstraintTypesLinear()
2969 after reading a problem to classify linear constraint types
2970- public methods SCIPvariableGraphBreadthFirst() and SCIPvariableGraph{Create,Free}() to
2971 perform breadth-first search on the variable constraint graph used by the GINS and ALNS heuristics
2972- SCIPsetProbingLPState() to install given LP state and/or norms at the current probing node
2973- SCIPbranchcandGetLPMaxPrio() and SCIPbranchcandGetExternMaxPrio() to query the maximal branching priority of given
2974 branching candidates; also added SCIPbranchcandGetNPrioLPCands() to access the number of LP candidates with this priority.
2975- SCIPupdateSolIntegralityViolation(), SCIPupdateSolBoundViolation(), SCIPupdateSolLPRowViolation(),
2976 SCIPupdateSolConsViolation() and SCIPupdateSolLPConsViolation() for updating numerical solution violations, as well as
2977 SCIPactivateSolViolationUpdates() and SCIPdeactivateSolViolationUpdates() for activating/deactivating violation updates globally
2978- SCIPsetSubscipDepth() to set the depth of SCIP as a copied subproblem during problem stage
2979- SCIPdivesetGetNSols() to query the number of found solutions from a diveset.
2980- SCIPnextafter() that wraps different nextafter methods to return the next representable value after a given value
2981- SCIPlinConsStats{Create,Free,GetTypeCount,GetSum}() and SCIPprintLinConsStats() to work with linear constraint classification through the C API
2982- SCIPgetRowNumIntCols() that returns the number of integer columns in a row
2983- SCIPsetSlackVarUb() to control upper bound of slack variable in cons_indicator
2984
2985- Data structures:
2986 - methods SCIPrandomCreate() and SCIPrandomFree() are no longer public and should be replaced by SCIPcreateRandom() and
2987 SCIPfreeRandom(), respectively (the new methods respect the global parameter `randomization/randomseedshift` automatically)
2988 - methods SCIPdigraphCreate() and SCIPdigraphCopy() are no longer public and should be replaced by SCIPcreateDigraph() and
2989 SCIPcopyDigraph(), respectively, which receive a SCIP argument and are more robust towards future interface changes
2990
2991- Bilinear:
2992 - SCIPgetAllBilinearTermsQuadratic() to access data of all existing bilinear terms in quadratic constraints
2993 - SCIPaddBilinearIneqQuadratic() to propose an inequality with two variables that appear in a bilinear term
2994 - SCIPcomputeBilinEnvelope{1,2}() to compute a linearization of a bilinear term when considering at most two linear inequalities
2995
2996- Clique:
2997 - SCIPcliqueGetIndex() which returns the unique identifier for the given clique
2998 - SCIPgetNCliquesCreated() which returns the number of cliques created so far
2999
3000- Cutting plane separation methods:
3001 - SCIPisCutNew() that returns whether a cut is already present in the global cut pool
3002 - SCIPgetSepaMinEfficacy() to access separating/minefficacy(root)
3003
3004- Interfaces:
3005 - interface methods to create and use bandit algorithms implemented as SCIP core plugins
3006 - interface methods for aggregating rows and computating MIP cuts, see cuts.h
3007 - interface method SCIPsetRandomSeed() to (re)set a random number generator seed
3008
3009### Command line interface
3010
3011- new interactive shell functionality to display linear constraint classification types;
3012 use `display linclass` after reading a problem to classify linear constraint types
3013- new command line parameter `-r` to pass a nonnegative integer as random seed.
3014
3015### Interfaces to external software
3016
3017- added interface to the NLP solver WORHP
3018- added interface to the NLP solver FilterSQP
3019- added interface to graph automorphism algorithms in `src/symmetry/` (initially only to BLISS)
3020- unify handling of objective limit in LPIs by replacing LPI parameters `SCIP_LPPAR_LOBJLIM` and `SCIP_LPPAR_UOBJLIM` by
3021 `SCIP_LPPAR_OBJLIM`
3022- dropped support for MOSEK < 7.0.0.0
3023
3024### Changed parameters
3025
3026- changed and removed several parameters for zerohalf separator
3027- replaced `constraints/quadratic/disaggregate` by `constraints/quadratic/maxdisaggrsize` to bound
3028 the total number of created constraints when disaggregating a quadratic constraint
3029- new value 3 for parameter `lp/solutionpolishing` to enable LP polishing only during probing and diving mode
3030- parameter `conflict/useboundlp` has new values `d` (only dual solution analysis) and `b` (both, conflict and dual solution analysis)
3031
3032- Heuristics:
3033 - fixed typo `heuristics/completesol/maxunkownrate` has changed to `heuristics/completesol/maxunknownrate`
3034 - replaced parameter `heuristics/{clique,vbounds}/minfixingrate` by `heuristics/{clique,vbounds}/minintfixingrate` and
3035 `heuristics/{clique,vbounds}/minmipfixingrate`, which check the fixing rate before LP solving and after sub-MIP presolve
3036
3037- Separating:
3038 - parameter `separating/maxstallrounds` only applies to nodes in the tree (not the root node, anymore); use the new
3039 parameter `separating/maxstallroundsroot` for the root node
3040 - moved parameters for flowcover and cmir separators to `separating/aggregation`
3041
3042- Removed parameters:
3043 - `constraints/{abspower,bivariate,nonlinear,quadratic,soc}/scaling`
3044 - `constraints/{abspower,bivariate,quadratic,nonlinear}/mincutefficacysepa`
3045 - `constraints/{abspower,bivariate,quadratic,nonlinear}/mincutefficacyenfofac`
3046 - `constraints/soc/minefficacy`
3047 - `conflict/usemir`
3048 - `conflict/prefermir`
3049 - `heuristics/clique/{multiplier,initseed}`
3050 - `separating/feastolfac`
3051 - `separating/orthofac`
3052 - `separating/cgmip/allowlocal` (use parameter passed to separation callback instead)
3053 - `separating/{gomory,strongcg}/maxweightrange`
3054
3055### New parameters
3056
3057- `conflict/prefinfproof` (prefer infeasibility proof to boundexceeding proof)
3058- `conflict/sepaaltproofs`
3059- `constraints/indicator/maxsepanonviolated` to stop separation after separation of non violated cuts
3060- `constraints/orbisack/coverseparation` (whether orbisack cover inequalities should be separated)
3061- `constraints/orbisack/orbiSeparation` (whether facet defining inequalities for orbisack should be separated)
3062- `constraints/orbisack/coeffbound` (maximal value of coefficients in orbisack facet inequalities)
3063- `constraints/orbisack/checkpporbisack` (check whether orbisacks can be strengthened by packing/partitioning constraints)
3064- `constraints/orbisack/checkalwaysfeas` (whether conscheck returns always `SCIP_FEASIBLE`)
3065- `constraints/orbitope/checkpporbitope` (check packing/partitioning orbitopes)
3066- `constraints/orbitope/sepafullorbitope` (separate full orbitopes)
3067- `constraints/orbitope/checkalwaysfeas` (whether conscheck returns always `SCIP_FEASIBLE`)
3068- `constraints/quadratic/{usebilinineqbranch,minscorebilinterms,bilinineqmaxseparounds}`
3069- `constraints/quadratic/disaggrmergemethod` to change the strategy of how to merge independent blocks of quadratic constraints
3070- `constraints/quadratic/mincurvcollectbilinterms` to change the minimal curvature of constraints
3071 to be considered when returning bilinear terms to other plugins
3072- `constraints/quadratic/binreformbinaryonly` to disable reformulation of products of binary and non-binary variables
3073- `constraints/symresack/ppsymresack` (check whether symresacks can be strengthend by packing/partitining constraints)
3074- `constraints/symresack/checkalwaysfeas` (whether conscheck returns always `SCIP_FEASIBLE`)
3075- `expbackoff` to all separators which increases the frequency exponentially over the depth in the tree
3076- `heuristics/completesol/{beforepresol,maxlpiter,maxcontvars}`
3077- `heuristics/{clique,vbounds}/maxbacktracks` to limit the number of backtracks in the fix-and-propagate phase
3078- `heuristics/{clique,vbounds}/uselockfixings` to enable fixing of additional variables based on variable locks
3079- `heuristics/vbounds/{feasvariant,tightenvariant}` to specify the fixing variants used by the vbounds heuristic
3080- `lp/refactorinterval` to change the refactorization interval of the LP solver
3081- `misc/debugsol` to specify a debug solution that should be checked during the solve
3082- `misc/usesymmetry` to determine whether symmetry handling should be used
3083- `presolving/symbreak/conssaddlp` (whether symmetry handling inequalities should be added to the LP)
3084- `presolving/symbreak/addsymresacks` (whether symresacks should be used to handle symmetries)
3085- `presolving/symbreak/computeorbits` (whether symmetry orbits should be computed)
3086- `presolving/symbreak/detectorbitopes` (whether it should be checked if some symmetries can be handled by orbitopes)
3087- `presolving/symmetry/computepresolved` (Whether symmetries are computed after presolving)
3088- `presolving/symmetry/maxgenerators` (maximal number of generators generated by symmetry detection)
3089- `presolving/symmetry/checksymmetries` (whether validity of computed symmetries should be verified)
3090- `propagating/obbt/{itlimitfactorbilin,minnonconvexity,createbilinineqs}`
3091- `propagating/vbounds/minnewcliques` to specify the minimum number of new cliques to trigger another clique table analysis
3092- `propagating/vbounds/{maxcliquesmedium,maxcliquesexhaustive}` to limit the number of cliques relative to the
3093 number of binary variable for performing clique table analysis
3094- `separating/maxincrounds`
3095- `separating/maxlocalbounddist`, `separating/maxcoefratio` and `separating/intsupportfac`
3096- if PaPILO >= 2.1: `presolving/milp/maxbadgesizepar` to limit the maximal badge size if PaPILO is called in parallel mode
3097- if PaPILO >= 2.1: `presolving/milp/maxbadgesizeseq` to limit the maximal badge size if PaPILO is called in sequential mode
3098
3099### Data structures
3100
3101- new type `SCIP_Shortbool` (equal to uint8_t) for storing Boolean values in a more compact manner
3102- new disjoint set data structure `SCIP_DISJOINTSET` to incrementally update connectedness information for a graph on nodes {0,...,n-1}
3103- new red black tree data structure defined in `src/scip/rbtree.{c,h}`
3104- new object `SCIP_LINCONSSTATS`, see type_cons.h, to work with linear constraint classification through the C API
3105- added new type `SCIP_TABLE` together with callbacks to output SCIP statistics
3106
3107Unit tests
3108----------
3109
3110- added several tests for the LP interface
3111- added tests that cover nonempty linear constraint classification types
3112- added tests for the double double arithmetic, the new red black tree data structure, the nlpi, obbt, interval arithmetics,
3113 symmetry computation, objective function changes in probing, computing envelopes of bilinear function, relaxation enforcement
3114
3115Build system
3116------------
3117
3118- added interface to the NLP solver WORHP; set `WORHP=true` in order to link to WORHP
3119- added interface to the NLP solver FilterSQP; set `FILTERSQP=true` in order to link to FilterSQP
3120
3121### Cmake
3122
3123- added support for sanitizers in debug mode and options SANITIZE_ADDRESS, SANITIZE_MEMORY, SANITIZE_UNDEFINED, SANITIZE_THREAD
3124- added option SYM to specify which graph automorphism package (bliss, none) should be used, if available
3125- disable non-standard compliant floating point optimizations in combination with intel compilers
3126- improve Visual Studio compilation
3127- only accept IPOPT version 3.12.0 or higher
3128- preserve correct rpath in library (e.g. path to libipopt) when installing
3129
3130### Makefile
3131
3132- new flag `DEBUGSOL={true,false}` to enable checks against a user given debug solution
3133- added flag SYM to specify which graph automorphism package (bliss, none) should be used
3134- default value for ZIMPL in the Makefile is now `false`
3135
3136Fixed bugs
3137----------
3138
3139- fix wrong statistic display of diving leaf solutions
3140- fixed order of SCIPcalcCliquePartition() in corner case where no cliques are available
3141- fix treatment of infinite lower bound in proximity objective cutoff
3142- fixed minor issue in expression graph simplification
3143
3144- Separator:
3145 - fix linear knapsack relaxation during separation if a binary variable does not have a solution value in [0,1].
3146 - fixed potential ressource leaks in SCIPsolveLinearProb(), expr.c, sepa_eccuts, cons_cumulative.c, cons_nonlinear.c
3147 - fixed bug in cons_orbitope.c, where wrong terminating index in separation of SCIs was used
3148 - fixed wrong mapping of permuted basis indices in gomory separator
3149 - fixed integer objective separator for objective scales < 1
3150
3151- Presolver:
3152 - fixed numerical issues in boundshift presolver when aggregating integer variables
3153 - fixed aggregation of variables in boundshift presolver that contain large variable bounds
3154
3155- Heuristic:
3156 - fixed bug in feasibility pump heuristic when switching on the `usefp20` parameter
3157 - fixed handling of LOOSE variables in locks heuristic
3158 - fixed creation of conflicts in clique heuristic for incomplete LPs
3159
3160- Constraints:
3161 - fixed bug in mps reader. Reader now prints `OBJSENSE` section and tries to generate unique names of constraints
3162 - fixed upgrade to a varbound constraint if abspower constraint contains a multi-aggregated variable
3163 - fixed several bugs related to hashing of constraints/rows in cutpool.c and cons_linear.c
3164 - fixed registration of almost fixed nonlinear variables in abspower constraints
3165
3166- Propagator:
3167 - fixed releasing of variables in the genvbounds propagator in case the problem could be solved during presolving of a restart
3168 - fixed numerical issues in bound widening of variable bound constraint handler and vbound propagator during conflict analysis
3169
3170@page RN40 Release notes for SCIP 4.0
3171
3172@section RN401 SCIP 4.0.1
3173*************************
3174
3175Features
3176--------
3177
3178- added parsing functionality to cardinality constraint handler for CIP format
3179- allow to relax objective limit in reoptimization in presolved stage
3180- suppress excessive printing about numerical troubles in LP on default verblevel (high)
3181
3182Performance improvements
3183------------------------
3184
3185- only accept passed improving solutions in heur_indicator
3186- add and use RESTRICT macro for some pointers
3187- sorting of parents and children for some expression types is now independent of memory layout
3188
3189- Constraints:
3190 - widened a bottleneck in simplifying long signomial sums in a nonlinear constraint
3191 - unified and extended code that improves numerics of cuts generated by nonlinear constraint handlers
3192
3193- Separation:
3194 - stop separation in cons_indicator after maxsepanonviolated many non violated separated cuts
3195 - improve choice of variable to enter support in separation of cons_indicator
3196
3197Interface changes
3198-----------------
3199
3200### New API functions
3201
3202- SCIPvalidateSolve() to compare solving result with an external primal and dual reference value
3203- SCIPisObjChangedProbing() to check whether the objective function has changed during probing mode
3204- SCIPgetDualSolVal() to get the dual solution value of a constraint
3205- SCIPisLPPrimalReliable() and SCIPisLPDualReliable() to check whether the current primal / dual LP solution
3206 were successfully checked for feasibility
3207
3208### Command line interface
3209
3210- New option in the interactive shell to validate the solution against an external primal and dual reference value
3211- added command line option `-o` and command `validatesolve` in interactive shell
3212 to validate the solution against an external primal and dual reference value.
3213
3214### Interfaces to external software
3215
3216- Updated and new interfaces to Mosek 8.1, GAMS and Gurobi
3217- new LP interface to Glop (Google OR tools); CMake only
3218
3219### Changed parameters
3220
3221- renamed parameter `heuristics/completesol/maxunkownrate` to `heuristics/completesol/maxunknownrate`
3222
3223Testing
3224-------
3225
3226- add options to make test target (see Makefile section)
3227
3228Build system
3229------------
3230
3231### Cmake
3232
3233- New CMake build system alongside the usual Makefile setup
3234
3235### Makefile
3236
3237- added make options for specifying EXECUTABLE and OUTPUTDIR variables for the make test target
3238
3239Fixed bugs
3240----------
3241
3242- fixed unintended behavior of interrupt signal handler inside SCIP copies
3243- fixed uninitialized values in SCIP's digraph data structure after calling SCIPdigraphResize()
3244- fixed issue related to SCIPcreateFiniteSolCopy() not being able to remove all infinite fixings
3245- fixed issue in SCIPcopyLimits() w.r.t. soft time limit
3246- fixed bug in dynamic resizing of hashtables and hashmaps
3247- added workaround for bug in primal simplex of cplex 12.7.1.0 occuring when attempting to solve LPs without rows without presolving
3248- fixed bug in binpacking example that might have led to doing the same branching several times
3249- fixed memory issue in binpacking example
3250- in GAMS writer, forbid also various parenthesis characters in gams symbol names
3251- added missing definition of `SCIP_UNUSED` in memory.h if def.h is not included
3252- treat reopt bugs: Avoid numerical problems with changing objective; fix check for changed objective
3253- fixed reading issue in mps reader: integer variables fixed to 0 or 1 are treated as binaries now,
3254 allowing to use them as indicator variables
3255- afternode heuristics are now called even if the node limit was reached and the solving process will be stopped
3256 after the current node
3257- fixed bug when activating probing mode with a non-empty separation storage
3258
3259- LP interfaces:
3260 - fixed guard against using old Gurobi versions in lpi_grb.c: Gurobi 7.5 was not permitted
3261 - fixed wrong handling of unboundedness status in lpi_grb.c
3262 - fixed wrong handling of row basis status in lpi_grb.c
3263
3264- Propagator:
3265 - fixed bug in shift and propagate--variable information with a negation transformation is correctly reset after backtracking
3266 - fixed bug in genvbounds propagator when applying a restart after the root node
3267
3268- Constraints:
3269 - fixed bug in varbound coefficient tightening: if a varbound constraint only contained one variable afterwards,
3270 it may have been deleted without applying the induced bound, if the change was too small, this is now forced
3271 - fixed potential wrong locks update after a varbound constraint became redundant in coefficient tightening
3272 - fixed potentially wrong cleanup of fixed variables in nonlinear constraint handler
3273 - fixed memory leak in OSiL reader when using SOS constraints
3274
3275- Solution:
3276 - improved handling of infinite values in a primal solution in quadratic and nonlinear constraints
3277 - fixed bug in computing violation and cut for certain nonlinear constraints when LP solution is slightly out of bounds
3278 - fixed debug solution check that appeared in probing mode when the objective function has changed
3279 - relaxed a too strong assert concerning solutions close to the objective limit
3280
3281@section RN400 SCIP 4.0.0
3282*************************
3283
3284Features
3285--------
3286
3287- Introduced support for partial or infeasible user solutions, which SCIP tries to complete/repair heuristically
3288- implemented linear time methods for (weighted) median selection for joint arrays of various types
3289- added adaptive solving behavior of SCIP based on solving phases and heuristic transitions, if enabled via `solvingphases/enabled`
3290- can now solve relaxations within probing
3291- in case of multiple relaxators the best solution is saved instead of the last one
3292- added write callback for reader_bnd
3293- added possibility to use a reference value for advanced analysis of the tree search. If a finite reference value
3294 (an objective value in original objective space) is passed via misc/referencevalue, SCIP keeps track of the
3295 number of nodes exceeding the reference value and the number of early backtracks -- path switches in the tree when
3296 a child node with lower bound smaller than the reference value was available.
3297- added reading capabilities for partial solutions with extension *.mst
3298- new global shift off all random seeds (randomization/randomseedshift) and unification of all existing random seeds
3299- use new macros SCIPdebugMsg(), SCIPsetDebugMsg(), SCIPstatDebugMsg() at all places where it makes sense
3300- new random number generator in pub_misc.h
3301- add check whether variables have been released when freeing SCIP
3302- a print callback can now be specified for user expressions
3303
3304- LP Solutions:
3305 - will now enforce relaxation solution instead of lp or pseudosolution if lowerbound is better and the whole lp is included in the relaxation
3306 - new feature solution polishing to improve integrality of LP solutions
3307
3308- Constraints:
3309 - new constraint handler for cardinality constraints
3310 - added interval-evaluation of sine and cosine
3311 - allow to create constraints of constraint handlers that don't need constraints
3312 - New constraint handlers cardinality and components
3313
3314- Conflicts:
3315 - implement a storage for conflicts to have more control over active conflicts
3316 - Improved conflict analysis through central conflict pool and dual ray analysis for primal infeasible LPs; can now analyze dual
3317 unbounded rays of primal infeasible LPs
3318
3319- Presolving:
3320 - New presolvers that disaggregate SOC constraints and reformulate QP's by adding KKT conditions
3321 - new presolving step for variables contained in a single quadratic constraint with proper square coefficients
3322 - add new presolving step to disaggregate second order cone constraints
3323 - new presolving method presol_qpkktref to add the KKT conditions of a QP
3324 - implemented and extended stuffing presolving in linear constraint handler
3325 - new components constraint handler which replaces the components presolver; it searches for independent subproblems
3326 and solves small ones as sub-SCIPs during presolve, larger ones are solved alternatingly during the main solving process
3327 - new presolving timing FINAL: presolving methods with this timing are only called once after all other presolvers with timings
3328 FAST, MEDIUM and EXHAUSTIVE are finished; during this timing only reductions are allowed that are self-contained, e.g.,
3329 fixing all variables and deleting all constraints of an independent component; note that reductions found in this timing
3330 do not trigger a new presolving round
3331
3332- Separation and Cuts:
3333 - can now separate perspective cuts for indicator constraints
3334 - add sepa_convexproj, a separator which projects onto convex relaxation and build gradient cuts at the projection
3335 - add sepa_gauge, a separator which computes an interior point of a convex relaxation and performs a binary search in the segment joining
3336 the interior point and the point to separate until it finds a point in the boundary of the feasible region where to build a gradient cut
3337 - changed handling of coupling constraints in cons_indicator; the cuts will not be added to the pool, but are separated by default
3338 - concurrent solving mode that allows to run multiple SCIP instances, that share solutions and global variable bounds, in parallel
3339 - Revised pseudo random number generation and introduced central random seed for all plugins
3340
3341- Heuristics:
3342 - new Graph induced neighborhood search (GINS) primal heuristic that uses neighborhoods
3343 based on distances in the variable constraint connectivity graph.
3344 In addition, the heuristic supports a rolling horizon-like procedure to solve auxiliary problems
3345 for neighborhoods with increasing distance from the starting neighborhood.
3346 - new primal heuristic LP face that tries to find an integer solution inside the optimal LP face.
3347 - new heuristic that tries to complete partial solutions
3348 - the subnlp heuristic now gives ownership of a found solution to the heuristic that constructed the starting point, if any;
3349 as a consequence, MIP heuristics may now be shown more frequently for having found a solution when solving MINLPs, even
3350 though the solutions required an additional NLP solve
3351 - new multistart heuristic for NLPs
3352
3353- Propagator:
3354 - add prop_nlobbt, a nonlinear optimization-based bound propagator solving two convex NLP relaxations for each variable
3355 - nodes can now be postponed; currently, this can only be triggered by BEFORELP propagation callbacks
3356
3357- Statistic:
3358 + Extended statistic output displayable via the interactive shell
3359 + new statistic computed: `Root LP Estimate` that shows the root LP best-estimate with every pseudo-cost update
3360 + added leaf statistics about LP objective limit|feasible|infeasible leaves to the statistics output and
3361 to the callable library: SCIPgetNObjlimLeaves(), SCIPgetNFeasibleLeaves(), SCIPgetNInfeasibleLeaves()
3362 + next to the number of found solution, also the number of new best solutions is now printed for each heuristic
3363 (and relaxation solutions) in the statistics in the `Primal Heuristic` section.
3364
3365Performance improvements
3366------------------------
3367
3368- Extended the presolving timings by an additional timing FINAL for self-contained reductions
3369- Randomized tie-breaking in different parts of the code to reduce performance variability
3370- use connectedness information of the clique table to speed up the clique partitioning algorithm
3371- knapsack approximation algorithms use linear-time weighted median selection instead of sorting
3372- improved greedy solution in SCIPsolveKnapsackApproximatelyLT() for the flow cover separation
3373- reduce performance variability by using random numbers as tie-breaker for external branching candidates
3374
3375- Heuristics:
3376 - adjusted most Large Neighborhood Search heuristics such that they collect their variable fixings first in an array,
3377 and only create and populate a sub-SCIP if enough variables will be fixed.
3378 - reduce performance variability by using a small perturbation in the undercover heuristic
3379 - 1-opt heuristic can now be repeatedly executed as long as new incumbents are found
3380
3381- Constraints:
3382 - Improved and extended stuffing inside of linear constraint handler
3383 - Changed handling of coupling constraints in cons_indicator
3384 - SCIP supports constraint compression for problem copies; constraint compression denotes the immediate
3385 removal of fixed variables from constraint data at creation time to reduce memory requirements.
3386
3387- Propagation:
3388 - rewrote the propagate-and-cut-and-price loop so that successful propagations with DURINGLPLOOP timing, bound changes found by separation,
3389 and new primal solutions now trigger a new round of node solving, starting with propagation; improved tuning of propagation and heuristic timings
3390 - tuned propagation methods of several constraint handlers
3391 - make more use of SCIPmarkConsPropagate() to mark constraints for propagation and improved the internal handling of marked constraints
3392 - improve propagation of absolute-value expression in the case that the sign of the argument is fixed
3393
3394Interface changes
3395-----------------
3396
3397### New and changed callbacks
3398
3399- Concurrent SCIP:
3400 - extended interface to support concurrent solving mode
3401
3402- Constraint Handlers:
3403 - new optional callback `CONSENFORELAX` to enforce a relaxation solution, see \ref CONS
3404 - `CONSINITLP` callback now has a new parameter `infeasible`, which is a pointer to store whether infeasibility
3405 was detected while building the initial LP relaxation
3406
3407### Deleted and changed API methods
3408
3409- setting a parameter to a non-valid value now produces an error message instead of a warning
3410- bound reader uses angle bracket around variable names
3411- the parameters of SCIPlpiChgObj(), SCIPlpiSetBase(), SCIPlpiSetState(), SCIPlpiSetNorms() have been declared as const
3412- SCIPapplyHeurSubNlp() can now return the solution found by the sub-NLP heuristic
3413
3414- Random:
3415 - methods SCIPrandomGetInt() substitutes SCIPgetRandomInt() (marked to be deprecated)
3416 - methods SCIPrandomGetReal() substitutes SCIPgetRandomReal() (marked to be deprecated)
3417 - methods SCIPrandomPermuteArray() substitutes SCIPpermuteRandomArray() (marked to be deprecated)
3418 - methods SCIPrandomPermuteIntArray() substitutes SCIPpermuteRandomIntArray() (marked to be deprecated)
3419 - method SCIPrandomGetSubset() substitutes SCIPgetRandomSubset() (marked to be deprecated)
3420
3421- Conflict Analysis:
3422 - added parameters `conftype` and `iscutoffinvolved` to SCIPinitConflictAnalysis()
3423 that indicate the type of the conflict and whether the current cutoff bound is used or not
3424
3425- Constraint Handlers:
3426 - added parameter `infeasible` to SCIPinitlpCons()
3427
3428- Copying:
3429 - added parameters `fixedvars`, `fixedvals`, `nfixedvars` to SCIPcopyVars()
3430 - added parameters `fixedvars`, `fixedvals`, `nfixedvars` to SCIPcopyOrigVars()
3431 - renamed parameter `success` to `valid` in SCIPgetConsCopy()
3432
3433- Hashmap and Hashtable:
3434 - removed function SCIPcalcHashtableSize() since not required anymore for `SCIP_HASHTABLE` and `SCIP_HASHMAP`
3435 - based on the initial size `SCIP_HASHTABLE` and `SCIP_HASHMAP` choose an appropriate size internally to allow insertion of that
3436 many elements without resizing
3437 - `SCIP_MULTIHASH` behaves like the old `SCIP_HASHTABLE` and SCIPcalcMultihashSize() should be used as replacement for
3438 SCIPcalcHashtableSize()
3439
3440- Nonlinear Relaxation:
3441 - added parameter `curvature` to SCIPcreateNlRow()
3442
3443- Parameters:
3444 - the following new methods return a bool indicating whether the given value is valid for the parameter instead of printing a warning
3445 message and returning an error code if the value is invalid
3446 - renamed method SCIPcheckBoolParam() to SCIPisBoolParamValid()
3447 - renamed method SCIPcheckLongintParam() to SCIPisLongintParamValid()
3448 - renamed method SCIPcheckCharParam() to SCIPisCharParamValid()
3449 - renamed method SCIPcheckStringParam() to SCIPisStringParamValid()
3450 - renamed method SCIPcheckRealParam() to SCIPisRealParamValid()
3451 - in param.c/h: the new methods return a bool whether the given value is valid for the parameter instead of printing a warning message
3452 and returning an error code if the value is invalid
3453 - rename SCIPparamCheckBool() to SCIPparamIsValidBool()
3454 - rename SCIPparamCheckString() to SCIPparamIsValidString()
3455 - rename SCIPparamCheckChar() to SCIPparamIsValidChar()
3456 - rename SCIPparamCheckLongint() to SCIPparamIsValidLongint()
3457
3458- Primal Heuristics:
3459 - added parameter `initialseed` to SCIPcreateDiveset()
3460 - introduced new type `SCIP_HEURTIMING` for primal heuristic timing masks
3461 - changed type of parameter `timingmask` from unsigned int to `SCIP_HEURTIMING` in SCIPincludeHeur(), SCIPincludeHeurBasic()
3462
3463- Relaxators:
3464 - new parameter `includeslp` for SCIPincludeRelax() and SCIPincludeRelaxBasic()
3465 to indicate whether relaxation includes all linear rows and can be enforced
3466
3467- Reoptimization:
3468 - rename method SCIPgetReopSolsRun() to SCIPgetReoptSolsRun()
3469
3470- Solutions:
3471 - added parameter `completely` to SCIPtrySol(), SCIPtrySolFree(), SCIPcheckSol() to check all constraints when
3472 printing violations
3473
3474- Variables:
3475 - removed SCIPvarGetLbAtIndex() and added SCIPgetVarLbAtIndex()
3476 - removed SCIPvarGetUbAtIndex() and added SCIPgetVarUbAtIndex()
3477 - removed SCIPVarGetBdAtIndex() and added SCIPgetVarBdAtIndex()
3478 - removed SCIPvarWasFixedAtIndex() and added SCIPgetVarWasFixedAtIndex()
3479 - Removed method SCIPvarGetNBinImpls()
3480
3481### New API functions
3482
3483- added functions for concurrent solving mode (see concurrent.h, concsolver.h)
3484- SCIPcreateNlpiProb(), SCIPupdateNlpiProb() and SCIPaddNlpiProbRows() to create and update a nonlinear relaxation
3485- SCIPgetNObjlimLeaves(), SCIPgetNFeasibleLeaves(), SCIPgetNInfeasibleLeaves() for statistics output
3486 about LP objective leaves
3487- SCIPcheckCopyLimits() which can be used to check that enough time and memory is left to run a sub-SCIP after
3488 subtracting time and memory used by the main-SCIP and SCIPcopyLimits() which copies these limits accordingly and disables
3489 all other limits (need to be set by the plugin, if needed)
3490- SCIPcopyLargeNeighborhoodSearch() in heuristics.h that supports compressed copying and two kinds of problem copy: the MIP-relaxation or
3491 a 1-1 problem copy (by copying the constraints and not the LP relaxation)
3492- SCIPsolveProbingRelax() to solve a relaxation within probing
3493- SCIPgetLastStrongbranchingLPSolstat() to query the LP statuses after strong branching on a variable
3494- SCIPinitializeRandomSeed()
3495- SCIPswapReals() to swap two real values
3496- SCIPgetNNZs() to get the number of active non-zeros in the transformed/presolved problem
3497
3498- Debug Messages:
3499 - SCIPprintDebugMessage(), SCIPsetPrintDebugMessage(), SCIPstatPrintDebugMessage() that output debug messages and also print the
3500 subscip depth; the first two output via the message handler; also added macros SCIPdebugMsg(), SCIPsetDebugMsg(), SCIPstatDebugMsg()
3501 - SCIPdebugMsgPrint()/SCIPsetDebugMsgPrint() that output a message without `[debug]` prefix via the message handler (compare SCIPdebugPrintf())
3502
3503- Solution:
3504 - SCIPisDualSolAvailable() to query the dual solution availability
3505 - SCIPlpiSetIntegralityInformation() to improve SoPlex' solution polishing
3506
3507- Constraints:
3508 - library methods SCIPcopyConsCompression(), SCIPcopyOrigConsCompression() that accept an array of variables that are immediately
3509 fixed in the copy. Alternatively, local instead of global bounds can be used for compression.
3510 - library methods SCIPenableConsCompression(), SCIPisConsCompressionEnabled(), SCIPcopyConsCompression(), SCIPcopyOrigConsCompression()
3511 - SCIPgetIntVarXor() to access integer variable of XOR constraints
3512 - SCIPcreateConsCardinality() to create a cardinality constraint
3513 - SCIPcreateConsBasicCardinality() to create a basic cardinality constraint
3514 - SCIPchgCardvalCardinality() to changes cardinality value of cardinality constraint (i.e., right hand side of cardinality constraint)
3515 - SCIPaddVarCardinality() to add a variable to a cardinality constraint
3516 - SCIPappendVarCardinality() to append a variable to a cardinality constraint
3517 - SCIPgetNVarsCardinality() to get the number of variables in a cardinality constraint
3518 - SCIPgetVarsCardinality() to get the array of variables in a cardinality constraint
3519 - SCIPgetCardvalCardinality() to get the cardinality value of a cardinality constraint (i.e., right hand side of cardinality constraint)
3520 - SCIPgetWeightsCardinality() to get the array of weights of a cardinality constraint
3521 - SCIPgetLinvarMay{Decrease,Increase}Quadratic() to get index of a variable in linear term of quadratic constraint that may be decreased
3522 without making any other constraint infeasible
3523
3524- Parameters:
3525 - add SCIPparamIsValidInt() and SCIPparamIsValidReal() to param.c/h
3526 - add missing functions SCIPisIntParamValid() and SCIPisRealParamValid() to scip.c/h
3527
3528### Command line interface
3529
3530- new command line parameter `-v` to print detailed build options
3531
3532### Interfaces to external software
3533
3534- Interfaces for Python and Java are, among others, now available via http://www.github.com/scip-interfaces
3535- Revised documentation of the SCIP C-API to group methods more comprehensively by topics
3536- dropped support for Ipopt < 3.11
3537- Additional I/O-functionalities for debugging and logging in SCIP and in the AMPL interface
3538- updated CppAD to 20160000
3539- for users of the ampl interface, the display/logfile option has been added to set the name of a
3540 file to write the SCIP log to (additionally to stdout)
3541
3542- LP Interfaces:
3543 - SCIP uses the lpi_spx2 interface by default
3544 - Improved Gurobi interface that can handle ranged rows (requires Gurobi >= 7.0.2)
3545 - the CPLEX LPI now also compiles with CPLEX 12.7.0.0
3546
3547### Changed parameters
3548
3549- setting a value for a fixed parameter will no longer return with an error, if the new value equals the one to which the parameter is fixed
3550- changed value of parameter `separating/clique/cliquedensity` to 0.0 such that the separator always constructs a dense clique table
3551 which proved to be faster on the benchmarks MMM and stableset.
3552- parameters `misc/permutationseed`, `misc/permuteconss` and `misc/permutevars` changed to `randomization/permutationseed`,
3553 `randomization/permuteconss` and `randomization/permutevars`
3554- parameters `conflict/useinflp` and `conflict/useboundlp` are now of type char (before bool)
3555- all parameters of the components presolver (starting with `presolving/components/`) are now parameters of the components
3556 constraint handler (starting with `constraints/components/`)
3557
3558### New parameters
3559
3560- class randomization
3561- `branching/sumadjustweight` to adjust branching scores by adding a sum epsilon in order to keep score differences
3562 near zero, which are otherwise completely disregarded (they are adjusted to at least sum epsilon)
3563- `concurrent/∗ ` and `parallel/∗ ` for configuring the concurrent solving mode
3564- `constraints/cardinality/branchbalanced` to decide whether to use a balanced branching scheme in the enforcing of cardinality
3565 constraints
3566- `constraints/cardinality/balanceddepth` to set the maximal depth until balanced branching is turned off
3567- `constraints/cardinality/balancedcutoff` to determine that balanced branching is only used if the branching cut off value
3568 w.r.t. the current LP solution is greater than a given value
3569- `constraints/indicator/sepaperspective` to turn on separation of perspective cuts for indicator constraints
3570- `constraints/indicator/sepapersplocal` to decide whether local cuts can be used for perspective cuts for indicator constraints
3571- `constraints/quadratic/projectedcuts` to enable convex quadratics to generate gradients cuts at the
3572 projection of the point onto the region described by the constraint, which is supporting
3573- `lp/solutionpolishing` to enable LP polishing only at the root LP or always
3574- `misc/referencevalue` to pass a reference value for further analysis of the tree search, see also in `features`
3575- `presolving/qpkktref/addkktbinary` to allow the presence of binary variables for the KKT update
3576- `presolving/qpkktref/updatequadbounded` to add the KKT conditions to QPs only if all variables are bounded
3577- `presolving/qpkktref/updatequadindef` to add the KKT conditions to QPs only if the quadratic matrix is indefinite
3578- `randomization/lpseed` to set the initial seed of the LP solver
3579- `solvingphases/enabled` to activate adaptive behavior during the solution process; several further parameters
3580 in the solvingphases-section to control how to switch the parameters and whether a restart should be performed between the phases.
3581
3582### Data structures
3583
3584- new `SCIP_REGRESSION` data structure in pub_misc.h to incrementally compute a best-fit line through pairs of observations
3585- add maximum branch-and-bound tree depth constant `SCIP_MAXTREEDEPTH` (replaces SCIPgetDepthLimit() and SCIPtreeGetDepthLimit())
3586- new files heuristics.c/heuristics.h to collect methods that are frequently used by heuristics
3587- merged dive.c/pub_dive.h with heuristics.c/heuristics.h, removed dive.c/pub_dive.h
3588- separated header pub_misc.h from repeated methods for sorting and (weighted) median selection;
3589 those are also available in separate headers pub_misc_sort.h
3590 and pub_misc_select.h, but included into pub_misc.h
3591
3592Unit tests
3593----------
3594
3595- New unit testing system built on the Criterion framework
3596
3597Build system
3598------------
3599
3600### Makefile
3601
3602- All makefiles in `examples/` and `applications/` have been updated.
3603- `make.project` defines a variable `SCIP_VERSION` containing the SCIP version number
3604- revise sub-makefiles for MSVC on MinGW
3605- make shared libraries aware of their dependencies
3606- sub-makefile for CrayXC systems added
3607
3608- Places:
3609 - All objective files are now placed in `obj/static` or `obj/shared`, depending on `SHARED=false` or `SHARED=true`, respectively.
3610 - All internal and external libraries are placed in `lib/static` and `lib/shared`, the include files are in `lib/include`.
3611 - The binaries now contain an rpath to the SCIP directory, such that shared libraries are found.
3612
3613- Linking:
3614 - link binary to shared libs when compiling with `SHARED=true`
3615 - External projects (including make.project) can use the makefile variable LINKCXXSCIPALL or LINKCCSCIPALL to link all SCIP libraries.
3616 - Building with `SHARED=true` automatically generates the combined library libscipsolver.so for easier linking
3617
3618- Targets:
3619 - Running `make help` lists all makefile options.
3620 - `make install` copies now all header files
3621 - new target `dll` to build Windows dlls with MSVC
3622 - rename `dll` target to `windowslib`
3623
3624Fixed bugs
3625----------
3626
3627- fixed bug in event system: bound change events of the new focus node must be processed, even if the bound
3628 is the same as at the last focus node
3629- avoid numerically unstable (multi-)aggregations
3630- fixed bug in XML reader concerning comments
3631- the AMPL interface now writes a solve status (solve_result_num) into the .sol file
3632- in the cmpres.awk (allcmpres.sh) output, the counts in the time column are now with respect to the
3633 whole set of processed instances (as with fail and solv), while before it was with respect to the
3634 set of instances where no solver failed (eval set); thus, now proc = fail + time + solv.
3635- writing of solutions or parameters to a file now works also with the message handler set to quiet
3636- ignore lower and upper bound tightenigs beyond +/-infinity during solving
3637- time limit of SCIP-infinity is converted to LPI-infinity when setting it
3638- fix LP activity of a row that has been modified
3639
3640- Propagation:
3641 - fixed possible segmentation fault in genvbounds propagator
3642 - fixed bug with sorting of propagators in presolving: the order can be changed by calling probing; thus, there is a copy of the
3643 propagators, which is sorted by presolving priority
3644 - added missing capturing and releasing mechanism in genvbounds propagator
3645 - fix wrong propagation of product expressions
3646
3647- Constraints:
3648 - fixed wrong representation of SOC constraints in NLP
3649 - fixed a few issues within redundant constraint detection of (specialized) linear constraint handlers
3650 - fixed issue in reader_opb concerning writing of fixed variables contained in no constraints
3651
3652- Memory:
3653 - fixed memory bug in `SCIP_DIGRAPH`
3654 - improved counting of memory consumption by using more block memory and counting all allocated memory
3655 - fix memory leaks in TSP example
3656 - return `SCIP_ERROR` when a memory exception is caught in SoPlex (was `SCIP_LPERROR`)
3657 - fixed memory leak in OSiL reader
3658
3659- Objective:
3660 - fixed bug while changing the objective value of an original value after transforming the problem
3661 - fixed bug with solutions from previous runs not satisfying an objective limit
3662 - SCIPisObjIntegral() now works correctly in `SCIP_STAGE_PROBLEM`
3663
3664- Heuristics:
3665 - fixed two bugs in heur_indicator: use improvesols parameter now and update pointer to indicator constraint handler
3666 - fix wrong NLP representation of logic-or constraints in the dual value heuristic
3667 - correct handling of implicit integer variables with fractional solution value in simplerounding heuristic
3668 - fixed bug in heur_octane with uninitialized ray direction
3669
3670@page RN32 Release notes for SCIP 3.2
3671
3672@section RN321 SCIP 3.2.1
3673*************************
3674
3675Features
3676--------
3677
3678- new `force` parameter in (root)redcost propagator to run the propagator also with active pricers
3679
3680Performance improvements
3681------------------------
3682
3683- do not transfer solutions to original space, if SCIP is being freed
3684- modified implication graph analysis of SOS1 constraint handler; a new component allows to deduce zero fixings of variables
3685- made SOS1 constraint handler specific diving selection rule faster for the case that the SOS1 constraints do not overlap
3686- improved disjunctive cuts by the `monoidal cut strengthening` procedure of Balas and Jeroslow
3687
3688Examples and applications
3689-------------------------
3690
3691- several improvements of SCIP-Jack (STP application): extended presolving for STP variants, STP-specific branching
3692 rule, dual heuristic to generate initial LP relaxation
3693 SCIP-Jack is now competitive with problem specific state-of-the-art solvers on several well-known STP variants,
3694 e.g., the (rooted) prize-collecting Steiner tree problem.
3695- MultiObjective application renamed to PolySCIP; several improvements: better command line argument processing,
3696 overhaul of much of the source code, installation via CMake
3697
3698Interface changes
3699-----------------
3700
3701- made debug solution functionality thread safe (see debug.h for further information)
3702
3703### Deleted and changed API methods
3704
3705- add SCIPcomputeHyperplaneThreePoints() to compute a hyperplane containing three given 3-dimensional points
3706- SCIPsolveLinearProb() now uses a 1-dimensional matrix representation
3707
3708### Command line interface
3709
3710- added interactive shell command `display finitesolution` to print solution with infinite fixings removed,
3711 added reference to that method to `display solution` output if there are infinite fixings
3712- new interactive shell command `write history` to write the command line history (only when compiled with Readline)
3713
3714### Interfaces to external software
3715
3716- significantly improved Python interface to support user callbacks as well as linear and quadratic expressions
3717
3718### New parameters
3719
3720- `constraints/sos1/branchingrule` to decide whether to use neighborhood, bipartite, or SOS1 branching (this parameter
3721 replaces the old parameters `constraints/sos1/neighbranch`, `constraints/sos1/bipbranch`, and `constraints/sos1/sos1branch`)
3722- `constraints/sos1/depthimplanalysis` to limit the number of recursive calls of implication graph analysis
3723- `constraints/sos1/perfimplanalysis` to perform an implication graph analysis to deduce variable fixings and
3724 additional SOS1 constraints (this parameter replaces the old parameter `constraints/sos1/updateconflpresol`)
3725- `misc/transsolorig` for transfering transformed solutions to the original space (default: true)
3726- `propagating/rootredcost/onlybinary` to propagate root reduced costs of binary variables only
3727
3728### Data structures
3729
3730- renamed MIP matrix structure to `SCIP_MATRIX`
3731- changed the numeric values for `PRESOLTIMING` flags
3732
3733Build system
3734------------
3735
3736### Makefile
3737
3738- new target `dll` to build Windows dlls with MSVC
3739- add new compiling flag OPENSOURCE to allow/forbid the usage of third party software
3740
3741Fixed bugs
3742----------
3743
3744- fixed wrong objective sense when copying the original problem
3745- fixed a bug in merge step of cliques during clean up phase; method did not correctly handle infeasibility in the case of multiple
3746 variable-negation pairs
3747- fixed a previously untreated case in the linear cons simplification where coefficients only differ by slightly more than an epsilon
3748- fixed bug in parsing emphasis parameters which formerly led to completely wrong results
3749- fixed bug in the computation of the Wilcoxon test
3750- do not use the relative and absolute gap limit if no primal solution has been found so far
3751- fixed bug in conflict.c with wrong reset of bounds used
3752- fixed bug with transferring solutions to new runs (need to recompute objective before checking)
3753- fixed issue with infinite values when checking cuts for redundancy
3754- fixed library problems on Windows operating systems
3755
3756- Variables:
3757 - fixed wrong check when computing cuts for factorable quadratic functions bound tightening of a single variable
3758 - fixed wrong handling of loose variables in OBBT
3759 - fixed freeing of hash for binary variables
3760 - fixed bug during the computation of branching points for continuous variables which are almost fixed to +/- SCIPinfinity()
3761 - treated the case of integer variables as intermediate variables in the process of obtaining the active variable for a
3762 given binary variable
3763
3764- LP:
3765 - fixed a bug in dive.c that occurred when lpsolvefreq was set to 1; after a cutoff, the solution values of the
3766 linked LP solution might have become invalid
3767 - do not analyse an infeasible LP for conflicts during diving mode when LHS/RHS of rows were changed
3768 - use LPi infinity when reverting bound changes in conflict analysis
3769
3770- Heuristics:
3771 - fixed bug in heur_simplerounding in connection with relaxators
3772 - fixed bug in feaspump heuristic where last solution candidates were not updated correctly
3773 - fixed bug with infinite shift values in heur_shifting
3774 - fixed bug in shiftandpropagate heuristic: the heuristic did not correctly handle intermediate, global bound changes of the selected variable
3775 after its tentative fixing led to a cutoff.
3776
3777- Propagator:
3778 - (root) reduced cost propagators are not run anymore when doing branch-and-price,
3779 since they may install upper bounds on variables which might interfere with the
3780 pricing (they may be enabled again by their force parameters)
3781 - fixed too hard assertion in pseudoobj propagator
3782 - fixed a bug in shiftandpropagate where column positions after sorting are now correctly linked to their variables after sorting
3783 - fixed potential memory leak in genvbound propagator
3784
3785- Presolving:
3786 - fixed inconsistency in knapsack constraint handler data during presolving
3787 - fixed some problem with reoptimization when the problems are infeasible or have been solved in presolving
3788 - fixed endless loop in knapsack constraint handler when continuous variables change their types to binary during presolving
3789 - squares of binary variables might not have been replaced by the binary variable itself in presolve,
3790 if the variable was originally general integer and only became binary during presolve (due to bound tightening)
3791 - fixed bug in dive.c avoiding a check of constraints in the presence of indicator constraints
3792
3793- Constraints:
3794 - fixed numerical problems in computation of cuts for bivariate functions in quadratic constraint handler
3795 - fixed bug in quadratic constraint handler when computing lifted-tangent inequalities
3796 - fixed bug in nonlinear constraint handler when replacing a violated nonlinear constraint leads to an infinite
3797 - fixed bug in SOS1 constraint handler with inconsistent data structure after restart
3798 - fixed wrong handling of negated variables in bound tightening procedure of SOS1 constraint handler
3799 - fixed bug in simple fixing heuristic of SOS1 constraint handler
3800 - fixed two bugs in pseudoboolean constraint handler with wrong sorting of and constraints
3801 - fixed issue: constraints being parallel to objective function (after restart) sometimes led to wrongly stating infeasible
3802 - fixed bug during coefficient tightening in varbound constraint handler
3803 - handle cutoffs in cons_indicator detected by infeasible inequalities
3804 - fixed late change of type of slack variables in cons_indicator, if the bounds are not integral
3805 - fixed initsol and exitsol of cons_indicator, if problem has already been solved
3806 - fixed bug in cons_indicator with changing type of slackvariable
3807
3808@section RN320 SCIP 3.2.0
3809*************************
3810
3811Features
3812--------
3813
3814- added reoptimization feature for optimization problems with changed objective function or tighter feasible region
3815- the original problem can now be permuted directly after reading (if `misc/permutationseed` has value >= 0)
3816- added methods to compute strongly connected components with Tarjan's Algorithm
3817- added method to propagate implications of SOS1 variables
3818- convex quadratic contraints can now generate gradient cuts which are supporting to the feasible region
3819- SoPlex interface can now (re)store dual steepest edge weights
3820- extended expression parsing to support power, realpower and signpower operators; started support for user-defined operators
3821 in expression trees/graphs
3822- possibility to set a soft time limit which becomes active only after the first primal solution was found
3823- added matrix module for getting access to the internal mixed inter linear problem matrix
3824- better handling of large values returned by the LP solver
3825- added more checks to SCIP{alloc,realloc,duplicate}BufferArray() to handle overflows properly
3826- new plugin for reoptimizing a sequence of optimization problem that differ in the objective function, e.g., sequences arising from
3827 column generation
3828- new plugin `compr` for rearranging the search tree, currently this only works on the reoptimization tree
3829- moved assertions in comparison methods from scip.c to set.c
3830
3831- Constraints:
3832 - we can now upgrade quadratic constraints with one bilinear term to SOC constraints
3833 - we can also upgrade general quadratic constraints with a single negative eigenvalue to SOC constraints
3834
3835- Branching:
3836 - tighter reliability notions introduced for reliability branching, based on pseudo-cost relative errors
3837 and comparing candidates with the best pseudo-candidate using a 2-sample student-T test. These methods
3838 are used in disjunction with the existing reliability notion that uses a fixed number as reliability
3839 threshold for every variable before turning off strong-branching. This means, the classical method
3840 must be turned off by setting parameters minreliable and maxreliable to 0. The behavior is
3841 controlled through several parameters.
3842 - new distribution branching rule to base decisions on row activity (normal) distribution over domain space
3843 - can now output information for BAK: Branch-and-bound Analysis Kit
3844 - new score in hybrid reliability pseudocost branching that prefers nonlinear variables when solving MINLPs
3845 - new branching rule multaggr which allows to branch on general disjunctions defined by fractional multi-aggregated variables
3846 - new branching rules for SOS1 constraints for branching on a neighborhood or a complete bipartite subgraph of
3847 the conflict graph. In addition to variable domain fixings, it is sometimes also possible to add complementarity
3848 constraints to the branching nodes. This results in a nonstatic conflict graph, which may change dynamically
3849 with every branching node.
3850 - new branching rule nodereopt to reconstruct the tree after changing the objective function
3851
3852- Reader:
3853 - the MPS reader can now read semi-integer variables, they are handled by creating bound disjunction constraints
3854 - the MPS reader can now handle objective constants given as (the negation of) the RHS of the objective row
3855
3856- Separation:
3857 - obbt propagator applies now additional separation and propagation in order to learn stronger and more bound tightenings
3858 - extended probing mode to allow separation and objective coefficient changes
3859 - improved separation procedure of SOS1 constraint handler, including bound (clique) cuts and implied bound cuts
3860 - new disjunctive cut separator for SOS1 constraints
3861 - new edge-concave cut separator for quadratic constraints
3862
3863- Presolver:
3864 - Improved coordination of presolvers. There are three timings for presolvers now, FAST, MEDIUM and EXHAUSTIVE.
3865 Each presolving callback can specify one or more of these timings in which it will be called later.
3866 Within a presolving method, the current timing can be checked and the algorithms to be performed selected based on
3867 the timing. In one presolving round, first all presolving methods with timing FAST are called, sorted by priority.
3868 If they found enough reductions, a new round is started, otherwise, all presolving methods with timing MEDIUM are
3869 called. Again, with enough reductions, a new presolving round is started, too few reductions lead to running
3870 the EXHAUSTIVE presolvers. Similar to the delay concept used before, we are not neccessarily running all EXHAUSTIVE
3871 presolvers but stop as soon as one of them found enough reductions, starting a new presolving round immediately.
3872 - new presolving components for SOS1 constraints, including bound tightening and clique extension
3873 - new presolver tworowbnd for improving variable bounds and detecting redundant constraints added
3874 - new presolver dualagg for aggregating single up-/downlocked variables by a binary variable added
3875 - new presolver implfree for aggregating implied free variables added
3876 - new presolver redvub which can detect redundant variable upper bound constraints added
3877 - new presolver stuffing for fixing of singleton continuous variables added
3878
3879- Heuristic:
3880 - improved clique and variable bound heuristics
3881 - new heuristic distribution diving that bases its score function on the changes regarding solution density
3882 - variable histories can be transferred between sub-SCIPs solved by LNS heuristics and the component presolver
3883 and the main SCIP to reuse this information.
3884 - new heuristic heur_indicator that tries to make partial solutions with indicator constraints feasible. It also
3885 tries to improve them (or external solutions) by a one-opt local search.
3886 - new heuristic (heur_bound) which fixes all integer variables to their lower/upper bounds and solves the remaining LP
3887 - modified diving heuristics to handle SOS1 constraints
3888 - new primal heuristic for reoptimization 'ofins': objective function induced neighborhood heuristic
3889 - new heuristic for reoptimization which constructs solutions based in the changes between the objective function and the optimal
3890 solution before changing the objective function
3891
3892- Statistic:
3893 - extended variable branching statistics in the interactive shell by sample variance of unit gains
3894 - extended statistic output of interactive shell by more information on diving heuristic behavior
3895
3896Performance improvements
3897------------------------
3898
3899- improved treatment of nonlinearities in hybrid reliability pseudo cost branching
3900- using sparsity information of the SoPlex LP
3901
3902- Constraints:
3903 - improved vartype upgradability from continuous to implicit variables in cons_linear.c, depending on their objective coefficients
3904 - improved propagation of SOS1 constraint handler using the information from a conflict
3905
3906- Heuristics:
3907 - zi rounding heuristic uses buffer data structures, thereby decreasing total memory usage of SCIP
3908 - adjusted (hard) diving heuristics to solve fewer LPs. LP's are resolved only if a parameter-defined
3909 percentage of the variable bounds changed through domain propagation or at a predefined frequency.
3910 - some of the diving heuristics additionally consider indicator variables and SOS1 variables as candidate variables and try to
3911 make these constraint types feasible before passing a rounded solution to SCIPtrySol()
3912
3913- Presolving:
3914 - new presolving/propagation algorithm using the gcd for ranged rows and equations in cons_linear
3915 - added presolving levels (FAST, MEDIUM and EXHAUSTIVE) to allow better balancing of presolvers
3916
3917- Separation:
3918 - improved separation procedure of SOS1 constraint handler
3919 - improved separation procedure for convex quadratic constraints
3920
3921Examples and applications
3922-------------------------
3923
3924- two new applications for multi-objective optimization (PolySCIP) and the Steiner Tree Problem in Graphs
3925- new application for solving Steiner tree problems: SCIP-Jack can handle both the classical Steiner tree problem in graphs
3926 and 10 of its variants
3927
3928Interface changes
3929-----------------
3930
3931### New and changed callbacks
3932
3933- new callback function `SCIP_DECL_CONSGETDIVEBDCHGS` to provide
3934 constraint handler method to suggest dive bound changes during the generic diving algorithm, see type_cons.h for details
3935- new callback `SCIP_DECL_DIVESETGETSCORE` to implement scoring function to guide diving
3936
3937### Deleted and changed API methods
3938
3939- avoid potential comparisons of different infinity values by adjusting the LP solution value
3940- SCIPintervalSign(), SCIPintervalAbs(), SCIPintervalMax(), SCIPintervalMin(), SCIPexprgraphGetNodePolynomialMonomialCurvature(),
3941 and SCIPexprgraphTightenNodeBounds() need an infinity value to decide whether an interval is empty or not
3942- SCIPgetFeasibilityQuadratic() and SCIPgetActivityQuadratic() returns now a `SCIP_RETCODE` and needs an additional `SCIP_Real*` to
3943 store the result
3944- methods which support statistical tests in pub_misc.h, SCIPstudentTGetCriticalValue(), SCIPcomputeTwoSampleTTestValue() etc.
3945- SCIPsolveLinearProb() solves a linear problem of the form Ax=b for a regular square matrix A
3946- Added parameter `freesubscip` to SCIPapplyProximity()
3947
3948- Data structures:
3949 - Renamed method SCIPdigraphGetSuccessorsDatas() to SCIPdigraphGetSuccessorsData()
3950 - Renamed method SCIPdigraphGetNodeDatas() to SCIPdigraphGetNodeData()
3951 - Renamed method SCIPdigraphSetNodeDatas() to SCIPdigraphSetNodeData()
3952
3953- Constraint Handlers:
3954 - Renamed method SCIPconshdlrGetPropTimingmask() to SCIPconshdlrGetPropTiming()
3955 - new method SCIPconshdlrSetPropTiming()
3956 - Removed method SCIPconshdlrIsPresolvingDelayed()
3957 - Removed method SCIPconshdlrWasPresolvingDelayed()
3958 - SCIPmakeSOS1sFeasible() based on solution values, fixes variables to zero to turn all SOS1 constraints feasible
3959 - removed `delay(presol)` parameter from SCIPinclude{Conshdlr,Presol,Prop}() and added `(presol)timing` parameter
3960 - new parameter `presoltiming` for method SCIPpresolCons()
3961 - SCIPvarIsSOS1() returns whether some variable is involved in an SOS1 constraint
3962 - SCIPgetConflictgraphSOS1() gets conflict graph of SOS1 constraints
3963 - Added parameter `presoltiming` to SCIPpropCumulativeCondition()
3964 - Removed parameter `delaypos` from SCIPsetConshdlrPresol()
3965 - Added parameter `presoltiming` to SCIPsetConshdlrPresol()
3966 - Removed parameter `delaypos` from SCIPincludeConshdlr()
3967 - Added parameter `presoltiming` to SCIPincludeConshdlr()
3968 - Added parameter `consgetdivebdchgs` to SCIPincludeConshdlr() to provide a divebdchg-callback for the constraint handler
3969 to include
3970
3971- Branching Rules:
3972 - Added parameter `forcestrongbranch` to SCIPselectVarStrongBranching()
3973 - Added parameter `executebranching` SCIPexecRelpscostBranching()
3974 - Added parameters `ndomredsdown` and `ndomredsup` to SCIPgetVarStrongbranchWithPropagation()
3975
3976- LP and Cutting Planes:
3977 - Added parameters `inds` and `ninds` to SCIPgetLPBInvRow(), SCIPgetLPBInvCol(), SCIPgetLPBInvARow(), SCIPgetLPBInvACol(), and
3978 SCIPcalcStrongCG()
3979 - Added parameters `maxweight`, `weightinds`, `nweightinds`, and `rowlensum` to SCIPcalcMIR()
3980
3981- Variables:
3982 - SCIPvarGetNodeSOS1() returns node of SOS1 variable in the conflict graph
3983 - SCIPnodeGetVarSOS1() returns SOS1 variable associated to some given node in the conflict graph
3984 - Removed method SCIPvarGetNBinImpls()
3985
3986- Presolving:
3987 - Removed parameter `delaypos` from SCIPincludePresolBasic()
3988 - Added parameter `presoltiming` to SCIPincludePresolBasic()
3989 - Removed parameter `delaypos` from SCIPincludePresol()
3990 - Added parameter `presoltiming` to SCIPincludePresol()
3991 - Removed parameters `presoldelay` and `presoltiming` from SCIPincludePresol()
3992 - Removed parameters `presoldelay` and `presoltiming` from SCIPsetPropPresol()
3993
3994- Misc:
3995 - Added parameter `isequation` to SCIPaddClique()
3996 - Removed parameter `writeimplications` from SCIPwriteCliqueGraph()
3997 - Removed method SCIPallocBufferSize()
3998 - Removed method SCIPduplicateBufferSize()
3999 - Removed method SCIPreallocBufferSize()
4000 - Removed method SCIPfreeBufferSize()
4001 - Removed method callback SCIPdialogExecConflictgraph()
4002
4003### New API functions
4004
4005- started support for user-defined operators in expression trees/graphs (see SCIPexprCreateUser()),
4006 interface will likely change again in future SCIP versions
4007- new methods for mixed inter linear matrix access (see pub_matrix.h) added
4008- SCIPcomputeArraysIntersection() to compute the set intersection of two ordered arrays
4009- SCIPcomputeArraysSetminus() to compute the set difference of two ordered arrays
4010- SCIPcutGetLPActivityQuot() in pub_cutpool.h to get the potion of LP's where this cut was sharp in an optimal basis.
4011- SCIPpresolGetTiming(), SCIPpresolSetTiming(), SCIP{conshdlr,prop}GetPresolTiming(), and SCIP{conshdlr,prop}SetPresolTiming()
4012- SCIPdigraphSetNSuccessors() sets the number of successors of some digraph node to a given value
4013
4014- Diving:
4015 - SCIPcreateDiveset() to add a diveset to a heuristic. Heuristics may have multiple divesets under different names
4016 - SCIPperformGenericDivingAlgorithm() that performs diving with periodic LP resolve according to the diveset argument.
4017
4018- Constraints:
4019 - new setter function SCIPsetConshdlrGetDiveBdChgs() in scip.h to set dive bound change callback for this constraint handler
4020 - SCIPaddDiveBoundChange() to add a diving bound change to the diving bound change storage of SCIP together with the information if this is a
4021 bound change for the preferred direction or not, to be used by constraint handlers inside the getDiveBdChgs-callback
4022 - SCIPchgCoefLinear() and SCIPdelCoefLinear() to modify linear constraint during problem creation
4023
4024- Memory:
4025 - BMSallocClearBlockMemoryArray()/SCIPallocClearBlockMemoryArray() and
4026 BMSallocClearBufferMemoryArray(), SCIPallocClearBufferArray() to allocate arrays that are initialized to 0
4027 - SCIPbuffermem() to get buffer memory;
4028
4029- Sort:
4030 - added new sorting functions SCIPsortRealRealRealBoolBoolPtr(), SCIPsortDownRealRealRealBoolBoolPtr()
4031 - added new sorting functions SCIPsortIntIntIntReal(), SCIPsortDownIntIntIntReal(), SCIPsortRealIntInt(), SCIPsortDownRealIntInt()
4032
4033- Param:
4034 - SCIPwriteParam() to write a single parameter to a file
4035 - SCIPcheckParam{Bool,Char,...}() to check whether a parameter value is within the feasible domain
4036
4037- Quadratic:
4038 - SCIPchgLhsQuadratic(), SCIPchgRhsQuadratic(), SCIPchgLinearCoefQuadratic(), SCIPchgSquareCoefQuadratic(),
4039 and SCIPchgBilinCoefQuadratic() to modify quadratic constraints during problem creation
4040 - SCIPgetFeasibilityQuadratic() and SCIPgetActivityQuadratic() to get the feasibility and activity of a quadratic constraint in a given solution
4041 - SCIPaddSquareLinearization(), SCIPaddSquareSecant(), SCIPaddBilinLinearization() and SCIPaddBilinMcCormick()
4042 in cons_quadratic.h to compute linear under- and overestimation for bilinear and quadratic terms
4043
4044### Command line interface
4045
4046- extended variable branching statistics and statistic output in the interactive shell (see Statistic section)
4047- submenu for setting `vbc` settings renamed to `visual`
4048- at the end of a command line run the best solution can now be output in the orignal space
4049
4050### Interfaces to external software
4051
4052- in the AMPL interface, variable and constraint attributes (flags) can now be set via suffixes, where 0 (unset) stands
4053 for the default, 1 for TRUE and other values for FALSE; see SCIPcreateVar() and SCIPcreateCons() for their meaning;
4054 for variables, `initial` and `removable` are recognized;
4055 for constraints, `initial`, `separate`, `enforce`, `check`, `propagate`, `dynamic` and `removable` are recognized
4056- the AMPL interface now passes an initial guess, if specified, as a solution (that will be checked for feasibility) to SCIP
4057
4058### Changed parameters
4059
4060- rowrepswitch set to 2.0, so row representation is activated if LP has at least 2 times more rows than columns
4061- one can now set emphasis parameters at the beginning of a settings file; it should start with `emphasis:` and
4062 the contain the emphasis string, e.g., `emphasis: feasibility` or `emphasis: heuristics off`.
4063
4064- Renamed parameters:
4065 - `vbc/filename` to `visual/vbcfilename`
4066 - `vbc/realtime` to `visual/realtime`
4067 - `vbc/dispsols` to `visual/dispsols`
4068
4069### New parameters
4070
4071- added parameter to switch pseudo cost update in diving heuristics (enabled by default)
4072- `branching/relpscost/confidencelevel` to set the confidence level to be used by statistical tests
4073- `branching/relpscost/higherrortol` to define the highest reliability threshold for relative error based reliability
4074- `branching/relpscost/lowerrortol` to define a lower reliability threshold for relative error based reliability
4075- `branching/relpscost/nlscoreweight` for weight of nonlinear score when branching on MINLPs
4076- `branching/relpscost/usedynamicconfidence` to use a dynamic confidence level based on the amount of
4077 strong-branching simplex-iterations compared to the overall simplex iterations (default is FALSE)
4078- `branching/relpscost/usehyptestforreliability` to enable strong branching decisions based on a 2-sample student-T test of all prior
4079 pseudo-cost observations between the best pseudo-candidate and the candidate for which to decide whether strong-branching should be applied
4080- `branching/relpscost/userelerrorreliability` to enable relative error based reliability
4081- `branching/relpscost/skipbadinitcands` for skipping strong-branching candidates whose estimated gain
4082 is significantly worse than the one of the locally best (sb or pseudo) candidate
4083- `constraints/linear/multaggrremove` to perform multi-aggregations in linear constraint handler only if the constraint can be removed afterwards
4084- `constraints/linear/rangedrowpropagation` to disabled newly implemented propagtion algorithm for ranged rows and equations
4085- `constraints/quadratic/advanced/interiorcomputation` to select the way of computing and interior point for gauge cuts
4086- `constraints/quadratic/gaugecuts` to enable convex quadratics to generate gradients cuts which are supporting
4087- `constraints/soc/generalsocupgrade` to allow general quadratics to be upgraded to soc
4088- `constraints/SOS1/addcomps` to add local complementarity constraints to the branching nodes (can be used in combination
4089 with neighborhood or bipartite branching)
4090- `constraints/SOS1/addbdsfeas` to define a minimal feasibility value for local bound (clique) inequalities in order to be
4091 added to the branching node
4092- `constraints/SOS1/addcompsdepth` to define the maximal depth for adding complementarity constraints
4093- `constraints/SOS1/addcompsfeas` to define a minimal feasibility value for local complementarity constraints in order to be
4094 added to the branching node
4095- `constraints/SOS1/autocutsfromsos1` to automatically switch to separating bound cuts from SOS1 constraints if the SOS1
4096 constraints do not overlap
4097- `constraints/SOS1/autosos1branch` to switch to SOS1 branching if the SOS1 constraints do not overlap
4098- `constraints/SOS1/conflictprop` to define whether to use conflict graph propagation
4099- `constraints/SOS1/bipbranch` to branch on a complete bipartite subgraph of the conflict graph
4100- `constraints/SOS1/boundcutsdepth` to define the node depth of separating bound (clique) cuts
4101- `constraints/SOS1/boundcutsfreq` to define the frequency for separating bound (clique) cuts
4102- `constraints/SOS1/boundcutsfromgraph` to define whether to separate bound (clique) inequalities from the conflict graph
4103- `constraints/SOS1/boundcutsfromsos1` to define whether to separate bound (clique) inequalities from SOS1 constraints
4104- `constraints/SOS1/fixnonzero`: If neighborhood branching is used, then fix the branching variable (if positive in sign)
4105 to the value of the feasibility tolerance
4106- `constraints/SOS1/implcutsdepth` to define the node depth of separating implied bound cuts
4107- `constraints/SOS1/implcutsfreq` to define the frequency for separating implied bound cuts
4108- `constraints/SOS1/implprop` to define whether to use implication graph propagation
4109- `constraints/SOS1/maxaddcomps` to define the maximal number of complementarity constraints added per branching node
4110- `constraints/SOS1/maxboundcuts` to define the maximal number of bound (clique) cuts separated per branching node
4111- `constraints/SOS1/maxboundcutsroot` to define the maximal number of bound (clique) cuts separated per iteration in the root node
4112- `constraints/SOS1/maximplcuts` to define the maximal number of implied bound cuts separated per branching node
4113- `constraints/SOS1/maximplcutsroot` to define the maximal number of implied bound cuts separated per iteration in the root node
4114- `constraints/SOS1/maxextensions` to define maximal number of extensions that will be computed for each SOS1 constraint in presolving
4115- `constraints/SOS1/maxsosadjacency` to define that the adjacency matrix of the conflict graph is not created in presolving if
4116 the number of SOS1 variables is too large
4117- `constraints/SOS1/maxtightenbds` to define the maximal number of bound tightening rounds per presolving round
4118- `constraints/SOS1/neighbranch` to branch on a neighborhood of the conflict graph
4119- `constraints/SOS1/nstrongiter` to define the maximal number LP iterations to perform for each strong branching round
4120- `constraints/SOS1/nstrongrounds` to define the maximal number of strong branching rounds to perform for each node (only
4121 available for neighborhood and bipartite branching)
4122- `constraints/SOS1/sos1branch` to branch on a single SOS1 constraint, i.e., a clique of the conflict graph
4123- `constraints/SOS1/sosconsprop` to define whether to use SOS1 constraint propagation
4124- `constraints/SOS1/strthenboundcuts` to define whether to strengthen bound (clique) cuts in case bound variables are available
4125- `constraints/SOS1/updateconflpresol` to update the conflict graph during the presolving procedure
4126- `display/allviols` to print all violated constraints of the best solution during checksol in the scip shell
4127- `heuristics/indicator/improvesols` that turns on the improvement of external solutions by one-opt
4128- `heuristics/∗diving/lpresolvedomchgquot` to determine the percentage of changed domains since previous LP to trigger
4129 an LP resolve [default: 0.15] (* stands for eight diving heuristics to support this feature)
4130- `heuristics/∗diving/lpsolvefreq` to determine the frequency for resolving LP's during the execution of
4131 this heuristic [default: 1, use 0 for a dynamic setting based on the number of domain reductions]
4132 (* stands for eight diving heuristics to support this feature)
4133- `heuristics/shiftandpropagate/binlocksfirst` to set if binaries without locks should be preferred in ordering
4134- `heuristics/shiftandpropagate/maxcutoffquot` to select a maximum percentage of allowed cutoffs before stopping the heuristic (default is 0.0)
4135- `heuristics/shiftandpropagate/selectbest` to trigger if shiftandpropagate should select the best candidate in every round
4136 (set to FALSE for static order) (default is FALSE)
4137- `limits/autororestart` for triggering an automatic restart after this many nodes, or -1 for no auto restart [default is -1]
4138- `limits/softtime` to set a soft time limit (active only after first primal solution was found)
4139- `misc/allowobjprop` to allow objective function propagation
4140- `misc/allowdualreds` to allow dual reductions
4141- `misc/outputorigsol` to control whether at the end of a command line run the solution should be output in the orignal space
4142- `numerics/checkfeastolfac` to scale feasibility tolerance when checking the feasibility of best found solution
4143 after the solving process finished (e.g., checksol in scip shell)
4144- `separating/cutselrestart` for cut selection during restart copy process (`a`ge, activity `q`uotient) [default is `a`]
4145- `separating/cutselsubscip` for cut selection for sub SCIPs (`a`ge, activity `q`uotient) [default is `a`]
4146- `separating/disjunctive/maxconsdelay` to delay separation of disjunctive cuts if number of SOS1 constraints is larger than predefined value
4147- `separating/disjunctive/maxdepth` to define the node depth of separating disjunctive cuts
4148- `separating/disjunctive/maxinvcuts` to define the maximal number of disjunctive cuts investigated per iteration in a branching node
4149- `separating/disjunctive/maxinvcutsroot` to define the maximal number of disjunctive cuts investigated per iteration in the root node
4150- `separating/disjunctive/maxrank` to define the maximal permissible rank of a disjunctive cut that could not be scaled to integral coefficients
4151- `separating/disjunctive/maxrankintegral` to define the maximal permissible rank of a disjunctive cut that could be scaled
4152 to integral coefficients
4153- `separating/disjunctive/maxrounds` to define the maximal number of separation rounds of disjunctive cuts in a branching node
4154- `separating/disjunctive/maxweightrange` to define the maximal valid range of simplex tableau row weights
4155
4156### Data structures
4157
4158- new enum `SCIP_CONFIDENCE_LEVEL` for different levels of confidence for statistical tests.
4159- new struct `SCIP_DIVESET` that bundles options for SCIP's diving heuristics; all hard diving heuristics (those
4160 without `obj` at the beginning) include diveset and implement only the scoring callback.
4161- rename all file `*_vbc.?` to the more generic `*_visual.?`
4162- moved buffer memory handling to blockmemory/memory.?;
4163 remove files type_buffer.h, struct_buffer.h buffer.h buffer.c;
4164 removed functions SCIP*buffer*() from scip.? and replaced them by macros;
4165 redesigned buffer interface to be similar to block memory; added checks for strange sizes
4166
4167Testing
4168-------
4169
4170- added scripts and targets for testing with xpress (see Makefile section)
4171
4172Build system
4173------------
4174
4175### Makefile
4176
4177- new parameter `DELHEADERS` for `uninstall`-target: scip headers are only removed when invoking `make uninstall DELHEADERS=true`
4178- added scripts check_xpress.awk, check_xpress.sh, evalcheck_xpress.sh and check_cluster_xpress.sh and target
4179 `testclusterxpress` and `testxpress`
4180
4181Fixed bugs
4182----------
4183
4184- fixed bug in primal.c and tree.c by using SCIPinfinity() as a cutoffbound to delete child nodes
4185- fixed bug in lp.c which leads to wrong primal and dual feasibility
4186- fixed wrong handling of infinite activities and primal values in sepastore.c and lp.c
4187- fixed bug that led to an erroneous warning about the clock type
4188- fix behavior of `make install` which now sets symbolic links and short links to binaries and libraries
4189- fix bug which lead to wrong global bound tightenings in prop_genvbounds.c
4190- fix call to random generator for Windows operating systems in misc.c
4191- fixed again a bug in backward propagation of linear expressions in expression graph
4192- fixed bug in prop_symmetry.c, where an incorrect weak symmetry handling constraint got added.
4193
4194- NLP:
4195 - fixed bug in heur_nlpdiving.c: wrong counting of fix variables
4196 - fix wrong handling of `SCIP_NLPSOLSTAT_LOCALINFEASIBLE` solution status in nlp.c
4197 - fix characterization of logic or constraints in SCIP's NLP relaxation
4198
4199- Branching:
4200 - fixed wrong comparison when executing branching rule for external branching candidates
4201 - fix spatial branching on implicit integer variables
4202 - fix wrong comparisons of values larger/less than +/- SCIPinfinity() in branch.c, lp.c and sol.c
4203 - fixed problem with lpisrelax flag in probing mode when doing branch-and-price
4204
4205- Constraint Handlers:
4206 - try to handle fixings of multi-aggregated variable in cons_sos1 presolving and avoid error
4207 - fixed bug in pseudoboolean constraint handler about negated variables
4208 - fixed assert in cons_soc.c: now soc with 1 lhs variable are allowed
4209 - fixed wrong assert in cons_indicator (slack variables might be replaced by active variables that have nonzero objective)
4210 - fix late creation of auxiliary LP in cons_nonlinear.c, which lead to a segmentation fault with lpi_spx2.cpp
4211 - fixed bug in cons_abspower.c: do not generate cuts with infinity right-hand-side anymore
4212 - fixed setting of enforcement flag for constraints created by reformulation in nonlinear constraint handlers
4213 - fixed bug in cons_indicator with handling local bounds
4214
4215- Memory:
4216 - fix potential memory leak in SoPlex LP interfaces when setting invalid basis
4217 - fix potential memory leak in method SCIPgetConsCopy()
4218 - fix potential memory leak in method detectRedundantConstraints() of the knapsack constraint handler
4219
4220- Interval arithmetic:
4221 - fix handling of infinite intervals in SCIPintervalIsEmpty()
4222 - fixed bug in intervalarith.c: bivariate quadratic equations may have been solved wrongly if second variable is unbounded
4223
4224- Quadratic Constraints:
4225 - fix wrong sorting of bilinear terms in cons_quadratic
4226 - fix potentially tightening of LB/UB of a variable to +/- infinity in cons_quadratic
4227 - fixed bug in cons_quadratic.c which leads to an overflow when SCIP allocates memory for a dense matrix
4228 - fixed bug in cons_quadratic.c: do not generate linearization cuts for disabled constraints
4229 - fix missing clean phase of bilinear terms with zero coefficient in cons_quadratic.c
4230
4231@page RN31 Release notes for SCIP 3.1
4232
4233@section RN311 SCIP 3.1.1
4234*************************
4235
4236Features
4237--------
4238
4239- use clock average to reduce number of system calls via `timing/rareclockcheck` parameter
4240- added copy mechanism for conjunction constraints
4241- added revised lpi_xprs for using XPRESS as LP solver
4242
4243Performance improvements
4244------------------------
4245
4246- improved solving of LPs in OBBT propagator
4247- improved activity-delta computation and thereby propagation for linear constraints
4248- improved memory management of proximity heuristic
4249- disabled statistic timing in all subscips via new parameter `timing/statistictiming`
4250
4251Interface changes
4252-----------------
4253
4254### New and changed callbacks
4255
4256- rename array arcdatas in digraph to arcdata
4257- changes in clock type are now transferred to SoPlex
4258- corrected wrong primal bound in statistics for unbounded problems
4259- forbid to call SCIPfixVar() in `SCIP_STAGE_PRESOLVED` stage, which is not allowed since it calls SCIPchgVarLb/Ub()
4260
4261### Deleted and changed API methods
4262
4263- rename SCIPdigraphGetNodeDatas() to SCIPdigraphGetNodeData();
4264- rename SCIPdigraphSetNodeDatas() to SCIPdigraphSetNodeData()
4265- SCIPapplyProximity() has an additional parameter freesubscip, which causes the method to free
4266 the created subscip automatically at the end.
4267
4268### New API functions
4269
4270- SCIPhasPerformedPresolve() to check, e.g., whether LP duals are accessible
4271- SCIPconvertRealTo[Long]Int() to convert reals that represent integers to [long] ints.
4272- SCIPisDualfeasEQ() and related to perform checks w.r.t. to the dual feasibility tolerance
4273- SCIPdeleteSubproblemProximity() to free proximity subproblem manually as external caller
4274
4275### Command line interface
4276
4277- added dialog for writing the finite solution (calling SCIPcreateFiniteSolCopy() before writing)
4278
4279### Interfaces to external software
4280
4281- AMPL interface now returns dual multipliers if problem is an LP and presolving was turned off
4282
4283### Changed parameters
4284
4285- changed default value of parameter `heuristics/proximity/minimprove` to 0.02; previous value was 0.25
4286- changed default value of parameter `heuristics/proximity/usefinallp` to FALSE
4287
4288### New parameters
4289
4290- `timing/rareclockcheck` to call the system time less frequently, based on the current average time interval
4291 between two calls to SCIPsolveIsStopped(); the default value is FALSE
4292- `timing/statistictiming` to enable/disable all timers for statistic output of SCIP; the default value is TRUE
4293
4294### Data structures
4295
4296- renamed MIP matrix structure to `SCIP_MATRIX`
4297- changed the numeric values for `PRESOLTIMING` flags
4298
4299Build system
4300------------
4301
4302### Makefile
4303
4304- added Makefile support for cygwin 64 Bit
4305- allow to turn off block and buffer memory by the makefile parameters NOBLKMEM, NOBUFMEM, NOBLKBUFMEM;
4306 also remove the now superfluous makefiles for noblkmem, nobufmem, noblkbufmem
4307
4308Fixed bugs
4309----------
4310
4311- fixed wrong conversion of reals representing negative integer values
4312- in debug mode, SCIP checks that no NaN's are introduced in SCIPsolSetVal()
4313- fixed bug 697 (and 699), calling SCIPsolve() after the problem was already solved and SCIPfreeSolve() was called now
4314 does nothing anymore
4315- added support for character `#` in variable names in old non-linear CIP format (i.e., names without `<` and `>`)
4316- fixed bug 702, removed too hard assert when casting too big values into `SCIP_Longint`
4317- branching for continuous variables with unbounded intervals now takes `branching/clamp` into account
4318- forbid aggregations with scalar smaller feastol or larger 1/feastol
4319- fixed bug 683, not recognizing errors/segfaults especially in free stage of SCIP by improving the check scripts
4320- fixed bug where quieting a message handler also disabled writing to files other than stdout
4321- fixed bug 708, special case of implications led to a fixing
4322- fixed bug, variable bounds detected wrong infeasibility
4323- another bug fix when computing the original variable sum of a given variable in SCIPvarGetOrigvarSum()
4324- fixed setting solution value of multi-aggregated var in xml-solution case
4325- fixed bug changing the variable type of an negated variable
4326- fixed numerical troubles in SCIPcreateFiniteSolCopy()
4327- fixed bug in SCIPpermuteProb(): if called before transforming the problem, data structures were not initialized yet
4328- fixed bug in aggregation procedure if two variables were of non-binary type but for one of the variables
4329 SCIPvarIsBinary() returned true
4330- treat activities of pseudo solutions as invalid when containing positive and negative infinity contributions
4331- fixed bug in GMI example: fractionality of slack variable is now computed correctly
4332- fixed LP interface of CPLEX: functions getBInv* return the correct sign of the coefficients.
4333- fixed bug in SCIPpermuteProb(), when called in transformed stage and non-active constraints exist
4334
4335- Dual:
4336 - use dual feasibility tolerance for comparisons regarding reduced costs
4337 - fixed bug in prop_dualfixing: don't fix variables to infinite values during solving
4338 - fixed sign of the dual multipliers returned by AMPL interfaces for maximization
4339
4340- Objective and Time Limit:
4341 - fixed wrong output of status when an objective limit was imposed but not reached yet
4342 - fixed the rare case that branching was performed even though strong branching found global bound changes leading to
4343 an infeasible/objlimit LP
4344 - fixed bug that objective limit was not reset correctly during SCIPfreeTransform() for maximization problems
4345 - fixed bug that hitting the time limit while solving a pure LP and then continuing the solving process lead to
4346 not solving the LP, but always creating a single child node until maximum depth is reached
4347
4348- Heuristic:
4349 - fixed bug leading to an incorrect dual bound when solving probing LPs within a DURINGPRICINGLOOP heuristic
4350 - fixed bug in proximity heuristic which attempted to enter diving mode even at nodes without a constructed LP
4351 - fixed wrong pseudo cost updates during diving heuristic execution after backtracking
4352 - fixed bug in heur_oneopt: avoid bound violations if shift value is negative due to infeasibilities
4353 - fixed bug that reaching a solution limit by beforenode heuristics lead to disregarding the current node if the
4354 optimization process was restarted later
4355 - fixed bug in trysol heuristic not saving the best solution in maximization problems
4356
4357- Presolve:
4358 - fixed bug in presolving of abspower constraints that lead to wrong variable locks
4359 - allow to call SCIPmarkConsPropagate() in INITPRESOLVE stage
4360 - fixed bug in components presolver with handling of dual fixable variables: unboundedness was not detected,
4361 better handle components with single variables by dual fixing propagator
4362 - issues in component solving by presol_components do not lead to stopping the overall process, anymore, the component
4363 is just disregarded
4364
4365- Memory:
4366 - fixed bug with freeing problem: need to reset objective limit
4367 - fixed memory leaks in case of erroneous parsing of constraints, e.g., non-linear constraints
4368 - fixed missing memory allocation for node data in digraphs
4369
4370- Constraints:
4371 - fixed bug in cons_quadratic which leads to wrong min/max activities
4372 - removed wrong break in cons_pseudoboolean
4373 - fixed bug in cons_varbound.c using the wrong constraint side for updating an upper bound
4374 - fixed bug in presolve of cons_nonlinear: wrong constraint upgrades may have been performed due to outdated bound
4375 information in expression graph
4376 - fixed bug in cons_setppc, wrongly aggregating variables if dual-presolving was disabled
4377 - fixed bug in cons_sos1: locks and events were not initialized if constraint was added to transformed problem
4378 - fixed bug in cons_setppc with dual presolving disabled
4379 - corrected copy of disjunction constraints
4380
4381- Reading:
4382 - allow to read numbers like `42856.` in lp-format
4383 - fixed bug(?) in reader_mps: variables are now written in columns section even of they occur in no constraint
4384 and have an objective coefficient of 0 (otherwise, CPLEX and Gurobi cannot read the file)
4385 - fixed bug with reading `>=1` indicator constraints in LP-files
4386 - fixed bug in reader_lp which created two indicator constraints with the same name to trigger an equality
4387 - fixed bug when reading indicator constraints for linear constraints (equations/ranged rows) from MPS files
4388
4389@section RN310 SCIP 3.1.0
4390*************************
4391
4392Features
4393--------
4394
4395- added breadth first search node selection
4396- new node selection rule UCT which balances exploration and exploitation by considering node visits
4397- added possibility to not set a cutoff bound in the LP solver (can be enabled by setting `lp/disablecutoff` to TRUE)
4398- added missing debugging solution check for cliques
4399- added a data pointer to each node of the `SCIP_DIGRAPH`
4400- SCIPgetVarCopy() will now copy the original bounds when called for an original variable
4401- added upgrade of continuous variables to implicit variables for linear equations even if the coefficient is
4402 not equal to 1
4403- probing supports implicit binary variables
4404- added scaling to computation of relative interior point in SCIPcomputeLPRelIntPoint()
4405
4406- Solution:
4407 - added two methods to iterate over a sparse solution (`SCIP_SPARSESOLUTION`), see pub_misc.h
4408 - it is now possible to add an offset for the original problem instance, all original solutions will be initialized with
4409 this value and updated, when the offset is changed
4410 - extended and corrected dual feasibility checks for LP solution (controlled by parameter `lp/checkdualfeas`)
4411
4412- Cuts and Separation:
4413 - the rank of cuts is now stored and taken into account to improve numerical stability
4414 - added possibility to separate a cutpool w.r.t. a given solution (instead of LP-solution)
4415
4416- Branching:
4417 - new branching rule `cloud branching` that considers several alternative LP optima
4418 - additional vbc output added: branching information is printed earlier and also for nodes which were cut off
4419 - added support for strong branching with domain propagation in full strong and reliability pseudo cost branching
4420 - added strong branching with domain propagation support: in SCIPstartStrongbranch(), support for propagation can
4421 be enabled (uses the probing mode, some overhead compared to standard strong branching), after that
4422 SCIPgetVarStrongbranchWithPropagation() can be used to perform strong branching on a variable with previous domain
4423 propagation; similar to probing, valid bounds for variables are collected
4424 - strong branching with propagation can be enabled in fullstrong and relpscost branching rule
4425 - added possibility to store pricing norms of the LP solver (in addition to basis information) to speed up LP solving
4426 after a backtrack, e.g. in probing or strong branching with domain propagation
4427 - a pricer can now return that no further pricing should be done but rather early branching, even if it added variables
4428
4429- LP interface:
4430 - SoPlex (>= 1.7.0.5) can compute condition number of current basis matrix via LP interface
4431 - LPI files (lpi*.[h|c]) all moved from src/scip to src/lpi
4432
4433- Constraints:
4434 - added propagation method to cons_xor relying on Gaussian elimination, which can also produce feasible solutions
4435 - added first implication detection in cons_linear
4436 - cons_indicator can now try to construct feasible solutions from a cover
4437 - added possibility to forbid upgrading of linear constraints
4438 - new initial constraints are now added to the LP before solving a probing LP
4439 - first implementation of parsing for nonlinear constraints in CIP format
4440 - added upgrade from varbound constraints to set-packing constraints
4441 - added upgrade from bounddisjunction constraints to set-packing/logicor constraints
4442 - cumulative constraint handler adds disjunctive constraints (cumulative with capacity 1) for all jobs which cannot
4443 be processed in parallel
4444 - added new clique extraction algorithm for linear constraints
4445 - the slack variables of indicator constraints can now be scaled
4446 - added redundancy check of sides of ranged row varbound constraint
4447 - added coefficient tightening for ranged row varbound constraint
4448 - XOR constraint handler can add two extended formulations (flow/asymmetric, parameter `addflowextended/addextendedform`)
4449 - added multi-aggregation for binary variables with at most two uplocks and two downlocks, which emerge from set-
4450 partitioning or set-packing constraints
4451 - added upgrade from quadratic constraints to set-packing constraints
4452 - generalized the linking constraint handler
4453
4454- Reader:
4455 - can now read and write CIP-files with (multi-)aggregated variables
4456 - all readers now take the global parameters `reading/dynamic{conss|cols|rows}` and `reading/initialconss` into account
4457 - added reader_pbm, which writes the constraint-variable incidence matrix in pbm format (possibly scaled to given size)
4458 - reader_osil can now read SOS1 and SOS2 constraints
4459 - reader_lp and reader_mps are now able to write and-constraints in form of their (weak/strict) relaxation
4460 - added reading capability to GAMS reader (if compiling with GAMS=true, requires a GAMS system)
4461 - added capability of writing SOS1/2 constraints to GAMS reader (introduces extra variables and equations)
4462
4463- Heuristic:
4464 - new primal heuristics dual value
4465 - new LNS heuristic called `proximity`, which solves a problem in which a local branching constraint replaces the
4466 objective function which in turn is treated as additional constraint
4467 - new LP-based rounding heuristic (heur_randround) whose randomized rounding is biased towards the LP solution value;
4468 the heuristic uses the probing mode of SCIP to generate conflict clauses on the fractional variables
4469
4470- Presolving:
4471 - added new dual presolving for setppc-constraints
4472 - changed dualfix presolver to propagator such that dual fixing can also be applied during repropagation of the root node
4473 - added full-dual presolving step in setppc constraint handler
4474 - dual solution can now be displayed for pure LPs when no presolving was performed
4475 - added clique presolving for xor constraints
4476 - added presolving using pairs of variable bound constraints that use the same variables
4477 - added more presolving to cons_indicator, checking whether indicator/slack variables are aggregated
4478 - added presolve.{c,h} which should be used for all preprocessing mechanisms executed from within SCIP, corresponding to
4479 solve.{c,h} and also for presprocessing methods which can be called from different plugins or from the core to avoid
4480 code doubling
4481 - return error if variable should be fixed to infinity after presolving (LP-solvers do not handle this consistently)
4482 - in verblevel `SCIP_VERBLEVEL_FULL`, the number of non-zeros will be output for the original and presolved model
4483 - new presolving step for tightening logicor constraints using implication and clique information
4484 - several new presolving steps for linear and knapsack constraints, using gcd information and many more
4485
4486- Statistic:
4487 - added average gap based on primal-dual integral to solution statistics; can be disabled via parameter
4488 `misc/calcintegral`
4489 - the statistics now include the value of the first LP solved at the root node (without cuts)
4490 - added new statistic which distinguishes between internal nodes and leaves which got processed
4491 - new section `Root Node` in statistics, listing objective value, iterations and solving time for the first LP solved
4492 at the root node as well as final dual bound of the root node and LP iterations for processing the root node
4493 (those where listed in the `Solutions` section before, named `Root Dual Bound` and `Root Iterations`)
4494
4495Performance improvements
4496------------------------
4497
4498- allow multiaggregation of binary variables
4499- shorten conflicts and deriving global boundchanges from conflicts
4500- apply lowerbound provided by pricers already during pricing loop, stop pricing if the lower bound computed by pricing
4501 already exceeds the cutoff bound
4502- improved performance of SCIPcliquelistDel(), SCIPcliquetableAdd(), SCIPcliquetableCleanup()
4503
4504- LP Solution:
4505 - strong branching LP solutions are checked for integrality
4506 - improved LP reoptimization for branch-and-price applications
4507 - improved numerical stability checks for LP solution
4508 - faster feasibility check of LP solutions (controlled by parameters `lp/checkprimfeas` and `lp/checkdualfeas`)
4509
4510- Presolver:
4511 - improved methods SCIPlpiGetBInv{Row,Col,ACol} for row representation in SoPlex LP interface
4512 - improved performance of method SCIPsolRetransform() when called during presolving with many aggregations
4513 - minor presolving performance improvements in cons_logicor.c and cons_knapsack.c
4514 - dual fixing presolver was turned into a propagator
4515 - many presolving improvements in constraint handlers
4516 - improved dual-presolving for setppc constraints in special cases
4517
4518- Constraints:
4519 - major improvements in pseudo-boolean constraint handler
4520 - performance improvement in domain propagation by marking constraints for propagation
4521 - added more constraint upgrading possibilities
4522 - improved handling of initial constraints created during solving
4523 - disabled scaling in feasibility check of nonlinear constraint handlers
4524 - conflict consisting of exactly two binary variables will be handled as set-packing constraint instead of an logicor
4525 constraint and the corresponding clique information is globally added
4526 - fasten repropagation for set-packing and -partitioning constraints
4527 - improved merging of and-constraints
4528 - disabled multi-aggregation in linear constraint handler when coefficients differ too much
4529 - improved multi-aggregation in linear constraint handler when only one variable in the aggregation has infinity
4530 contribution
4531 - added upgradability for implicit binary variable cases for linear constraints
4532
4533Examples and applications
4534-------------------------
4535
4536- new textbook Gomory mixed integer cuts example
4537
4538Interface changes
4539-----------------
4540
4541- removed all message length parameters in message.c and for printing error messages (not needed anymore)
4542
4543### New and changed callbacks
4544
4545- Domain Propagation:
4546 - added parameter `nmarkedconss` to SCIP_DECL_CONSPROP() callback which gives the number of constraints marked
4547 for propagation (these constraints are listed first in the conss array given as parameter).
4548
4549- Primal Heuristics:
4550 - Added parameter `nodeinfeasible` to SCIP_DECL_HEUREXEC() callback which states whether the current subproblem was
4551 already detected to be infeasible. In this case, the current LP solution might not respect local bounds and the
4552 heuristic must not assume that it does.
4553
4554- Variable Pricers:
4555 - Added parameter `stopearly` to callback method SCIP_DECL_PRICERREDCOST(). This boolean pointer should be used by the pricer
4556 to state whether early branching should be performed, even if new variables were added in the current pricing round.
4557
4558- Branching Rules:
4559 - new possible return value `SCIP_DIDNOTFIND` for SCIP_DECL_BRANCHEXECLP(), SCIP_DECL_BRANCHEXECPS(), and
4560 SCIP_DECL_BRANCHEXECEXT() callbacks to state that the branching rule searched, but did not find a branching.
4561
4562### Deleted and changed API methods
4563
4564- SCIPcalcMIR() takes an additional parameter sidetypes to determine which side of the rows to use
4565 (relevant for ranged rows)
4566- SCIPvarParseOriginal() and SCIPvarParseTransformed() now return the end of the parsed string
4567- SCIPgetConsCopy() now always captures the created constraint
4568
4569- Branching:
4570 - Added parameter `nfracimplvars` to SCIPgetLPBranchCands()
4571 - SCIPgetLPBranchCands() can be used to retrieve the number of implicit integer variables with fractional LP solution
4572 value via an additional pointer; the corresponding implicit integer variables can be accessed together with their
4573 fractionalities and solution values in the same way as binary and integer variables before; the arrays are sorted such
4574 that binary and integer variables precede the implicit integer variables; the method SCIPbranchcandGetLPCands()
4575 has been modified in the same way
4576
4577- LP and Cutting Planes:
4578 - Added parameter `sidetypes` to SCIPcalcMIR() to specify the specify row side type to be used.
4579 - Added parameter `cutrank` to SCIPcalcMIR() and SCIPcalcStrongCG() which stores the rank of the returned cut;
4580 via SCIProwChgRank() the rank of a cut can be changed (default rank is 0)
4581 - Added parameter `infeasible` to SCIPaddCut() which is a pointer to store whether the cut is infeasible for the
4582 local bounds.
4583 - SCIPgetLPObjval() now returns the LP value of the current (suboptimal) basis if the iteration limit is hit during LP
4584 solving (instead of -infinity); this value is not necessarily a valid dual bound and must not be used as such, but can
4585 be used as an objective estimate, e.g., if strong branching is simulated using the probing mode
4586 - removed parameter `normtype` from function SCIPcomputeLPRelIntPoint()
4587
4588- Misc:
4589 - Added parameter `lazyconss` to SCIPwriteMIP() to swith writing removable rows as lazy constraints.
4590 - Added parameter `enablepropagation` to SCIPstartStrongbranch(), which can be used to enable strong branching
4591 with domain propagation.
4592 - SCIPstartStrongbranch() has a new parameter `propagate` to enable or disable propagation support for strong branching
4593 - New method SCIPgetVarStrongbranchWithPropagation() which performs strong branching with propagation on a variable.
4594 - Added parameter `endptr` to SCIPparseVar() which stores the final string position after parsing.
4595
4596### New API functions
4597
4598- added SCIPdebugCheckConss() to the debugging mechanism and therefore created a `SCIP_SOL` (in original space) in debug.c
4599- before copying solutions to the original solution candidate storage, infinite solution values can now be removed using SCIPcreateFiniteSolCopy()
4600- SCIPsortLongPtrRealBool(), SCIPsortLongPtrRealRealBool(), SCIPsortLongPtrRealRealIntBool() and corresponding
4601 methods for sorting, insertion and deletion
4602- SCIPstoreSolutionGap() in scip.c, to store the gap when the first and last solution is found
4603- SCIPwriteCliqueGraph() which allows to write a graph with node weights for fractional variables
4604
4605- Separation:
4606 - SCIPconshdlrIncNCutsFound(), SCIPsepaIncNCutsFound() and SCIPsepaIncNCutsFoundAtNode() to increase the number of found cuts
4607 - SCIPseparateSolCutpool() to separate a cutpool w.r.t. a given solution
4608
4609- Constraint Handlers:
4610 - New method SCIPconshdlrGetStrongBranchPropTime() which returns the time used for domain propagation methods
4611 of the constraint handler during strong branching.
4612 - New method SCIPconsIsMarkedPropagate() which returns whether a constraint is marked for propagation.
4613 - New methods SCIPconsAddUpgradeLocks() and SCIPconsGetNUpgradeLocks() to increase or get the number of upgrade
4614 locks of a constraint.
4615 - New method SCIPgetNCheckConss() which returns the number of checked constraints.
4616
4617- Data structures:
4618 - New methods SCIPsparseSolGetFirstSol() and SCIPsparseSolGetNextSol() to get the first sparse solution
4619 or iterate over the sparse solutions, respectively.
4620 - New methods for the `SCIP_QUEUE` data structure in pub_misc.h to handle a (circular) queue, e.g., SCIPqueueCreate(),
4621 SCIPqueueFree(), SCIPqueueInsert(), SCIPqueueRemove(), SCIPqueueFirst(), SCIPqueueIsEmpty(), SCIPqueueNElems()
4622 - New method SCIPgmlWriteNodeWeight() to write a node section including weight to a .gml graph file.
4623 - New methods for hash tables: SCIPhashtableRemoveAll(), SCIPhashtableGetNElements(), SCIPhashtableGetLoad()
4624 - New methods in pub_misc.h to handle a resource activity, e.g., SCIPactivityCreate(), SCIPactivityFree(),
4625 SCIPactivityGetVar(), SCIPactivityGetDemand() ...
4626 - New methods for digraphs: SCIPdigraphResize() to resize the graph and SCIPdigraphSetNodeDatas() and
4627 SCIPdigraphGetNodeDatas() to set and get the data attached to the nodes.
4628
4629- Domain Propagation:
4630 - New method SCIPpropGetStrongBranchPropTime() which returns the time spent by a domain propagator during strong branching.
4631 - New methods SCIPmarkConsPropagate() and SCIPunmarkConsPropagate() to (un)mark a constraint for propagation.
4632
4633- LP and Cutting Planes:
4634 - New methods SCIPchgRowLhsDive() and SCIPchgRowRhsDive() to change left and right hand side of a row during diving.
4635 - Added parameter `cutoff` to SCIPsolveDiveLP(), SCIPsolveProbingLP(), and SCIPsolveProbingLPWithPricing()
4636 which is a pointer to store whether the diving/probing LP was infeasible or the objective limit was reached.
4637 - SCIPgetFirstLP{Dual/Lower}boundRoot() which return the value of the first LP solved at the root node
4638 - SCIPgetNRootFirstLPIterations() which returns the number of LP iterations for the first LP solved at the root node
4639 - SCIPlpiGetNorms(), SCIPlpiSetNorms() and SCIPlpiFreeNorms() for getting the LP pricing norms from the LP
4640 solver, loading them back into the solver and freeing the data
4641 - New method SCIPgetFirstLPTime() and SCIPgetNRootFirstLPIterations() to return time and iterations for the first LP solve
4642 and SCIPgetFirstLPDualboundRoot() and SCIPgetFirstLPLowerboundRoot() to return the first root LP dual and lower bound.
4643 - New method SCIPprintDualSol() which prints the dual solution for a pure LP (works only with preprocessing disabled).
4644 - New method SCIPisCutApplicable() which returns whether a cut is good enough to be applied.
4645
4646- Message Handler:
4647 - the main output routine of message.c (`bufferMessage` now handleMessage) has been rewritten: it now does not need
4648 a copy of the string to be output anymore, which makes the code much simpler (and also faster); it is passed a
4649 function pointer to the output function and uses it to directly output the (buffered) messages
4650 - New generic messagehandler output callback method SCIP_DECL_MESSAGEOUTPUTFUNC().
4651 - Removed parameter `msglength` from callback method SCIP_DECL_ERRORPRINTING().
4652 - New method SCIPmessageVPrintError() to print an error message.
4653 - Removed method SCIPmessagePrintWarningHeader().
4654
4655- Parameters:
4656 - New method SCIPparamGetCharAllowedValues() to get the allowed values for a char parameter.
4657 - New method SCIPgetParam() to get the parameter with a given name.
4658
4659- Variables:
4660 - SCIPapplyProbingVar() in prop_probing.h
4661 without deteriorating its objective value
4662 - SCIPshrinkDisjunctiveVarSet(), which takes an set of variables with corresponding bounds and boundtypes, and
4663 tries to derive global boundchanges and also to shorten this set of variables by using cliqe, implication and
4664 variable bound information
4665 - SCIPselectVarStrongBranching() to get the variable that fullstrongbranching would select
4666 - New method SCIPvarGetValuehistory() to get the value-based history of a variable.
4667
4668- Misc:
4669 - New method SCIPdoNotMultaggr() which returns whether multi-aggregation was disabled.
4670 - New method SCIPcreateFiniteSolCopy() to create a copy of a solution with infinite fixings removed.
4671 - New method SCIPadjustImplicitSolVals() which sets implicit integer variables to an integer value in the given
4672 solution without deteriorating its objective value.
4673 - New method SCIPcopyOrig() to copy the original problem. Analoguosly, use SCIPcopyOrigProb(), SCIPcopyOrigVars(),
4674 and SCIPcopyOrigConss() to copy original problem data, variables, or constraints, respectively.
4675 - New method SCIPwriteCliqueGraph() to write the clique graph in GML format into a given file
4676 - New method SCIPaddOrigObjoffset() to add an offset to the objective function.
4677 in original space and updates all orignal solutions correspondingly
4678 - New method SCIPcopyImplicationsCliques() to copy implications and cliques to a copied SCIP instance.
4679 - New method SCIPgetOpenNodesData() which returns all unprocessed nodes.
4680 - Added parameter `endline` to SCIPprintDisplayLine() to switch printing a newline symbol at the end of the line.
4681 - New method SCIPgetNLimSolsFound() returning the number of feasible primal solution respecting the objective limit.
4682
4683### Command line interface
4684
4685- allow dialog option to write clique graph
4686- dual solution values can now be obtained in the interactive shell after solving a pure
4687 LP without presolving
4688
4689### Interfaces to external software
4690
4691- new SoPlex 2.0 interface, can be enabled with `LPS=spx2`
4692- add support for SOS1 and SOS2 constraints to AMPL interface (see `interfaces/check/testset/SOS/sos?a.mod` for example)
4693- added copy of GAMS interface from COIN-OR/GAMSlinks project; GAMS-reader in SCIP can now read model instances from .gms files
4694- beta version of a python interface for the scipoptsuite is now available under interfaces/python
4695- beta version of a Java native interface is now available under `interfaces/jni`
4696
4697### Changed parameters
4698
4699- parameter `branching/scorefunction` has new value `q` for for `q`uotient branching score function
4700- replaced parameter `lp/checkfeas` by two parameters `lp/checkprimfeas` and `lp/checkdualfeas` to decide on primal and dual
4701 feasibility checks individually
4702- removed all local parameters `reading/(READER)/dynamic{conss|cols|rows}` and replaced them by global parameters
4703 `reading/dynamic{conss|cols|rows}`
4704- changed default value of parameter `numerics/dualfeastol` to 1e-7 for safer dual bounds from LP solver
4705- new possible values for parameter `heuristics/shiftandpropagate/sortkey` for sorting variables w.r.t. their norm,
4706 default changed from `u` to `v`, which means sorting downwards by violations
4707
4708- Constraints:
4709 - changed type of parameters `constraints/bivariate/scaling`, `constraints/quadratic/scaling`, `constraints/soc/scaling`
4710 from boolean to character
4711 - changed default for `constraints/{abspower,bivariate,nonlinear,quadratic,soc}/scaling` to off
4712 - changed default max coefficient for big-M constraint to be initial from 1e6 to 1e9
4713
4714- Separation:
4715 - changed default value of gomory cut separation parameter `separating/gomory/maxrank` from 0 to 3, to take also gomory
4716 cuts that could not be scaled to integral coefficients, with maximal rank 3 into account
4717 - remove parameter `separating/closecuts/relintnormtype`
4718
4719### New parameters
4720
4721- `branching/checksol` and `branching/heursbsol` to specify whether the strong branching LP solution
4722 should be checked for feasibility and whether a simple rounding heuristic should be run on this solution
4723- `branching/firstsbchild` and `branching/forceall` to specify the first child node to be
4724 investigated during strong branching (`u`p, `d`down, `a`uto) and whether always both children should be solved (only for
4725 strong branching with domain propagation, per default, the second child is not looked at when the first is infeasible)
4726- `conflict/fullshortenconflict` to decide whether we want to stop shortening a conflict set, when no
4727 global bound changes can be found anymore
4728- `conflict/maxvarsdetectimpliedbounds` to decide whether the a valid conflict of what maximal length
4729 will be used to derive global bound changes
4730- `constraints/{linear,knapsack}/detectcutoffbound` and `constraints/{linear,knapsack}/detectlowerbound`
4731 to enable/disable detection of constraint parallel to the objective function that will add an cutoffbound or an
4732 lowerbound respectively and these constraints will be prevented from entering the LP
4733- `constraints/and/upgraderesultant` to upgrade resultants of and constraints from binary to implicit binary variables, default is TRUE
4734- `constraints/abspower/scaling` and `constraints/nonlinear/scaling`
4735- `constraints/indicator/scaleslackvar` for scaling of the slack variable in indicator constraints
4736- `constraints/indicator/trysolfromcover` for trying to construct a feasible solution from a cover
4737- `constraints/linear/checkrelmaxabs` for checking linear constraints with a side of 0.0 relative to
4738- `constraints/linear/detectpartialobjective` to enable/disable the detection of sub-equations of the objective function
4739- `constraints/logicor/strengthen`, should pairwise constraint comparison try to strengthen constraints by removing superflous non-zeros?
4740- `constraints/xor/addextendedform` to add an extended formulation in XOR-constraints
4741- `constraints/xor/addflowextended` to add use the extended flow formulation in XOR-constraints
4742- `heuristics/<heurname>/lplimfac` for LNS heuristics to limit the number of LPs solved in a subproblem
4743 the maximum absolute value in the activity instead of 1.0
4744- `heuristics/shiftandpropagate/fixbinlocks` for fixing binary variables with no locks in one direction to the corresponding bound
4745- `heuristics/shiftandpropagate/collectstats` which decides whether variable statistics are collected
4746- `heuristics/shiftandpropagate/impliscontinuous` to decide whether implicit integer variables are treated as continuous variables
4747- `heuristics/shiftandpropagate/preferbinaries` and `heuristics/shiftandpropagate/stopafterfeasible`,
4748 which decide whether binaries should be shifted first and the shifting should be stopped when no violations are left
4749- `lp/disablecutoff` to toggle usage of LP cutoff bound (0: enabled, 1: disabled, 2: auto = disabled if pricers are used)
4750- `misc/calcintegral` (default TRUE) to trigger calculation of primal-dual integral
4751- `misc/finitesolutionstore` to switch whether infinite fixings should be removed from solutions before
4752 copying them to the original solution store
4753- `misc/permuteconss` and `misc/permutevars` to control whether variables and/or constraints should be permuted, if permutationseed != -1
4754- `presolving/components/feastolfactor` to increase the feasibility tolerance in all sub-SCIPs, when solving a component
4755- `propagating/obbt/conditionlimit` to discard instable LP bases
4756- `reading/(READER)/initialconss` that determines whether model constraints are initial
4757- `reading/cipreader/writefixedvars` for disabling printing of fixed variables in CIP format
4758- `reading/lpreader/aggrlinearization-ands` and `reading/mpsreader/aggrlinearization-ands` to enable/disable
4759 the printing of the weak or strict relaxation of and-constraints in LP and MPS format, respectively
4760- `reading/lpreader/linearize-and-constraints` and `reading/mpsreader/linearize-and-constraints` to
4761 allow and-constraints to be linearized when printing in LP and MPS format, respectively
4762- `separating/feastolfac` to allow dynamic decrease of relaxation feasibility tolerance depending on feasibility to applied cuts,
4763 i.e., allow relaxation solutions to have a primal infeasibility of at most this factor times the infeasibility of applied cuts
4764- `separating/gomory/sidetypebasis` to decide whether the sides of ranged rows should be determined from the basis status
4765- `separating/oddcycle/cutthreshold` to run odd cycle separation if not enough cuts have been found
4766- `separating/zerohalf/delayedcuts` to use the delayed cutpool for the zerohalf separator
4767- `write/allconss` to enable that all constraints are written
4768- `write/genericnamesoffset` when writing a generic problem to define an offset on the variable numbering
4769
4770### Data structures
4771
4772- New structure to store value-based branching and inference history (see pub_history.h).
4773- new data structure for (circular) queues (`SCIP_QUEUE`)
4774- hash tables will now increase dynamically
4775- Moved LP solver interfaces to subdirectory `src/lpi`.
4776
4777Testing
4778-------
4779
4780- added McNemar tests and Wilcoxon signed rank tests to cmpres.awk evaluation scripts
4781- added passing MEM option of testgams(cluster) target as workspace option to GAMS jobs
4782- extended test scripts by statistical tests
4783
4784Build system
4785------------
4786
4787### Makefile
4788
4789- default flag for ZIMPL is now `auto`, which means that it is built if and only if GMP is available (GMP=true)
4790- fixed make install for older Mac systems where install command does not have option -t
4791- dropped support for Ipopt < 3.10
4792
4793Fixed bugs
4794----------
4795
4796- fixed bug when adding (global) clique, implications or variable bound information in solving stage that lead to
4797 global bound changes which contradict local bounds and therefore need to be stored as pending bound changes
4798- unlinking a solution now copies solution values smaller than SCIPepsilon() avoiding some feasible solution in the
4799 transformed problem to be infeasible in the original problem
4800- fixed bug when flushing the warning buffer when SCIP is closed
4801- fixed bug when a bound change contradicts a local bound and is stored as pending, but the contradicting local
4802 bound becomes global afterwards (--> node where pending bound change is valid can be cut off)
4803- fixed statistics bug: externally given solutions and new solutions found while transforming existing ones
4804 are now listed in line `other solutions` of primal heuristics statistics
4805- fixed bug in random generators SCIPgetRandomInt() and SCIPgetRandomReal() for large intervals
4806- make sure that bound changes of negated original variables are correct
4807
4808- Branching:
4809 - fixed bug w.r.t. changing the variable branching priority beyond the problem stage
4810 - allow again branching on continuous variables with huge bounds
4811
4812- Separation:
4813 - fixed bug in sepa_cgmip computeObjWeightSize() w.r.t. equal sized rows
4814 - fixed wrong bound calculation in sepa_rapidlearning
4815 - fixed bug in flowcover separator to exclude unconstrained rows in aggregation
4816
4817- LP and Interfaces:
4818 - fixed bug that lead to resolving the LP after diving instead of restoring the buffered solution
4819 - fixed rare bug with conflict analysis and LP/LPI having different states after diving
4820 - fixed several bugs in lpi_grb
4821 - fixed wrong strong branching results in lpi_grb.c and an invalid write
4822 - fixed bug in handling max-function in ampl interface; added support for min-function
4823
4824- Presolving:
4825 - fixed bug in prop_dualfix w.r.t. to fixing of variables to infinity after presolving
4826 - fixed wrong presolving finished status which sometimes occurred when the time limit was hit during presolve
4827 - fixed bug where a limit on presolving rounds was exceeded by 1
4828 - fixed minor bugs in presolving in cons_setppc.c and cons_logicor.c
4829 - fixed minor bug in cons_linear w.r.t. disabled presolving
4830
4831- Propagators:
4832 - fixed bug in genvbounds propagator occurring when objective offset or scale changes after a restart
4833 - fixed bug in genvbounds propagator by replacing non-active variables on right-hand side after presolving
4834
4835- Readers:
4836 - fixed memory bug in reader_mps
4837 - fixed several minor bugs with handling of memory when writing aggregated variables (reader_lp, reader_mps)
4838 - fixed bug in reader_lp when writing bilinear terms (product sign was missing)
4839 - fixed bug in reading indicator constraints in mps-format
4840 - nonlinear readers now create auxiliary objective variables and constraints always as initial and not removable
4841 in order to avoid unbounded LPs due to loose variables with infinite best bound
4842
4843- Constraints:
4844 - fixed several bugs where variables or constraints were not freed correctly
4845 - do not multi-aggregate variables if the constant would be a huge value in order to avoid numerical troubles
4846 - fixed bug with infinite multi-aggregation constants
4847 - fixed output of aggregated variables in indicator constraints in lp and mps-format
4848 - improved handling of initial constraints: constraints which are initial, but added during the search to an already
4849 treated node are kept and added to the LP at every node where they are active
4850 - fixed bug in cons_superindicator concerning names of upgraded constraints
4851 - fixed bug in cons_indicator with trying to create solution in problem stage
4852 - fixed bug in cons_orbitope with fixing upper right triangle in non-root nodes
4853
4854Miscellaneous
4855-------------
4856
4857- new SCIP Optimization Suite homepages
4858
4859@page RN30 Release notes for SCIP 3.0
4860
4861@section RN302 SCIP 3.0.2
4862*************************
4863
4864Features
4865--------
4866
4867- reading erroneous CIP files can now output some indication of syntax errors
4868- can now run splint on core files
4869- cons_xor now uses the integral variable in propagation
4870- allowed to switch on/off the solution debugging
4871
4872Performance improvements
4873------------------------
4874
4875- improved SCIPlpiAdd{Cols,Rows}() in SoPlex LPi
4876
4877Examples and applications
4878-------------------------
4879
4880Interface changes
4881-----------------
4882
4883### New API functions
4884
4885- SCIPmarkColNotRemovableLocal() and SCIPmarkRowNotRemovableLocal() to forbid removal of an column/row
4886 from the LP in the current node
4887- SCIPmessageVPrintError()
4888
4889### Command line interface
4890
4891- can now output the solutions in the solution pool in the interactive shell
4892
4893### Interfaces to external software
4894
4895- updated Mosek LP interface to compile with Mosek 7
4896
4897Fixed bugs
4898----------
4899
4900- fixed bugs in solution counting
4901- fixed fieldtypes in sorting template
4902- fixed bug concerning the userinterrupt flag, which was not reset
4903- fixed solution collection when counting solutions
4904- fixed bug with storing original solutions
4905- fixed bug with infinite multi-aggregation constants
4906- fixed bug that removing reverse implication did not reset closestvblpcount
4907- fixed bug that duplicate solutions stopped copying of solutions to original solution candidate store
4908- forbid branching on variables with huge bounds; such huge values cannot be enumerated with fixed precision
4909 floating point arithmetics
4910- fixed bug that Ipopt's error message was not fully shown due to exiting before the message handler buffer was emptied
4911- unlinking a solution now copies solution values smaller than SCIPepsilon() avoiding some feasible solution in the
4912 transformed problem to be infeasible in the original problem
4913- allow to add columns (rows) with nonzero indices beyond current number of rows (columns) in SoPlex LPi
4914- updated get.ASL script to cope with broken ftp access to netlib server
4915
4916- Memory:
4917 - fixed bugs with freeing C++ object data for problem and variables
4918 - fixed memory leak in lp.c (probably never occurred so far since array was not used)
4919 - fixed bug in sepa_zerohalf.c where the maxcuts(root) parameters led to an invalid memory allocation call
4920
4921- LP:
4922 - fixed assert in solve.c with branched status and LP reached the objective limit
4923 - fixed bug in heur_oneopt.c and heur_clique.c which was caused by side-effects when calling SCIPconstructLP(); when
4924 adding new variables in this method (e.g. adding new variables needed for a relaxation), this changes the variables
4925 array of SCIP
4926 - fixed problem that diving did not save status for infeasible LPs
4927 - fixed bug in SCIPlpComputeRelIntPoint() with wrong iteration limit and with wrong recompution
4928 - fixed bug that old LP size was not updated for deadend if no LP was solved
4929
4930- Expressions:
4931 - fixed issues with ungraceful termination when encountering unsupported expression operands in AMPL interface
4932 - fixed bug in backward propagation of linear expressions in expression graph
4933
4934- Propagation:
4935 - fixed potential performance issue with tree depth always assumed to be zero when propagating in probing mode
4936 - fixed bug in prop_vbound w.r.t. creation of variables during the search
4937 - fixed several bugs in propagation of cons_xor: need to take integral variables into account
4938 - fixed bug in cons_abspower.c handling infinity values in propagation
4939 - fixed bug in cons_and.c when a constraint was not correctly propagated which led to wrong dual-presolve reductions
4940 - fixed bug in cons_abspower: wrong infinity check when propagating bounds
4941
4942- Presolving:
4943 - fixed bug that the number aggregated variables were not counted in presol_inttobinary.c
4944 - fixed bug in presol_domcol: locks are now checked to see whether rounding was forbidden for a variable
4945
4946- Reader:
4947 - fixed bug in reader_gms.c w.r.t. writing nonlinear expressions with polynomials with constants
4948 - fixed bugs in parsing bounds from CIP-files, in reader_gms and AMPL interface
4949 - fixed bug when reading a mps formated file with a missing bound in the bound section
4950
4951- Constraints:
4952 - fixed bug in cons_bounddisjunction with satisfied literal of multi-aggregated variable
4953 - fixed bug in upgrade method of cons_soc
4954 - fixed issue with negated variables in cons_xor.c
4955 - fixed several asserts in cons_xor presolving
4956 - fixed bug in cons_xor.c calling method on null pointer row
4957 - fixed bug using a too hard comparison on the objective-infeasible-decision in constraint enforcement
4958 - fixed possible cycling in enforcement of nonlinear constraints due to too early removal of newly added cuts from LP
4959 - fixed bug wrongly removing constraints locally while counting
4960 - fixed bugs in cons_bivariate.c when the nonlinear function is not differentiable on the boundary of the domain
4961 - fixed bug in cons_indicator.c:SCIPmakeIndicatorFeasible() with handling fixed variables
4962 - fixed bug in cons_integral: check integrality of implicit integer variables when a solution is checked for feasibility
4963 - fixed bug in Undercover with `pseudo-`quadratic constraints
4964 - fixed bug with quadratic constraints not being upgraded
4965 - fixed bug in intervalarith.c: bivariate quad. equations may have been solved wrongly if second variable is unbounded
4966
4967- Separation:
4968 - fixed bug in sepa_zerohalf.c not copying the displays to the subscip, but still changing a display parameter there
4969 - fixed iteration limit determination in sepa_closecuts
4970 - fixed bug in sepa_closecuts: need to make sure that variable values of separation point satisfy bounds
4971 - fixed bugs in sepa_oddcylce: number of arcs have to be adjusted, handle implicit binary variables,
4972 fixed bug in heuristic separation method, fixed asserts
4973 - fixed wrong bound calculation in sepa_rapidlearning
4974
4975@section RN301 SCIP 3.0.1
4976*************************
4977
4978Features
4979--------
4980
4981- added delayed cutpool which only gets separated if the sepastore is empty after a separation round
4982- sepa_cgmip can now take the objective row into account
4983- added possibility to run clang compiler
4984- statistics now include output on number of solutions that respect objective limit
4985
4986Performance improvements
4987------------------------
4988
4989- also copying active tight cuts from the delayed cut pool when calling SCIPcopyCuts()
4990- sort genvbounds only when root node is finished; apply more often
4991
4992Examples and applications
4993-------------------------
4994
4995Interface changes
4996-----------------
4997
4998- when using an objective limit, heuristic characters are not displayed any longer for worse solutions
4999
5000### Deleted and changed API methods
5001
5002- fixed spelling in the method name SCIPgmlWriteClosing()
5003
5004### New API functions
5005
5006- SCIPgetNLimSolsFound() to get number of solutions that respect the objective limit
5007
5008Fixed bugs
5009----------
5010
5011- fixed issue with applying the effective root depth during the search
5012- fixed bug concerning usage of dualbound and lowerbound
5013- fixed bug trying to color probing nodes, which are not added to the vbc output anymore
5014- fixed bug in sorting template
5015- fixed bug leading to removing a ranged row parallel to the objective function, although one of the sides was still needed
5016- fixed a bug correcting the binvarssorted flag in cons_linear.c
5017- fixed bug in cons_varbound.c not resolving multi-aggregated variables
5018- relaxed assert in SCIPvarCh{Lb,Ub}{Global,Local} that new bound must be tighter to feastol
5019- fixed contra-intuitive behavior when using SCIP with objective limits and solution limit at the same time;
5020 SCIP now only stops when sufficiently many solutions better than the objective limit have been found
5021- fixed bug when adding binary implications with non-vartype binary variables
5022- fixed bug adding binary implications on binary variables with type != `SCIP_VARTYPE_BINARY`
5023- fixed bug concerning different tolerances for reached objective limit in case of pricing with fastmip
5024
5025- LP:
5026 - fixed bug which disabled iteration limit in SCIPlpSolveAndEval()
5027 - ensure consistency of LP bounds during OBBT diving, i.e., that lower <= upper holds exactly
5028 - set lpsolstat to `SCIP_LPSOLSTAT_NOTSOLVED` in SCIPchg{Lp,Dual}feastol()
5029 - use tighter dual feasibility tolerance for LPs solved during optimization-based bound tightening
5030 - fixed bug with unflushed LP arising from global bound changes in strong branching
5031
5032- Constraints:
5033 - fixed issue with deleting varbound constraints in case the bound change was not applied
5034 - fixed bugs in parsing dis-/conjunctive constraints
5035 - fixed bug with handling of empty logicor and bounddisjunction constraints
5036 - fixed issue in cumulative constraint and separation
5037 - fixed bug when sorting knapsack constraints with the same weights
5038 - fixed bug resulting in trying to delete an upgraded linear constraint a second time in exitpre callback
5039 - fixed minor bug in conjunctive constraint handler printing wrong constraint
5040 - fixed bug in disjunctive constraint handler when enforcing a constraint
5041 - fixed behaviour change of indicator constraint handler when solving another instance after solving one using the
5042 interactive shell
5043 - fixed several issues in cumulative constraint handler
5044 - fixed bug in cumulative constraint handler w.r.t. getting active variables
5045 - fixed bug in cumulative constraint handler concerning conflict analysis
5046
5047- LPI and Interfaces:
5048 - fixed bug in CppAD in connection with abspower constraints
5049 - fixed bug in CppAD when using signpower functions with expression pointers that do not fit into an unsigned int
5050 - better handling of generalized (Lagrangian) variable bounds that are not in the LPI
5051 - fixed wrong basis rstat values in CPLEX LPI
5052 - fixed bug with LP not being flushed after bound changes on columns that are not in the LPI
5053 - methods SCIPlpiIs{PrimalFeasible,DualFeasible,DualUnbounded}() in SoPlex LPi now check that the LP is not perturbed,
5054 which may happen when stopping due to iteration or time limit
5055 - fixed inconsistencies between methods SCIPlpiIs{PrimalFeasible,DualFeasible,Optimal,...} in SoPlex LPi
5056
5057- Propagation:
5058 - fixed bug when adding linear constraints with non active variables in solving process, during propagation this
5059 resulted in changing the row, which is not possible for unmodifiable constraints/locked rows
5060 - fixed small issue in pseudo objective propagator w.r.t. propagating the lower bound globally
5061 - fixed bug in cons_orbitope: in rare cases one cannot repropagate
5062 - fixed bug of wrong result code in propagation in prop_genvbound.c
5063
5064- Presolve:
5065 - fixed bug in copying nonlinear constraints during presolve (resulted
5066 in wrongly declaring instances as infeasible when using component presolve)
5067 - fixed bug in copying nonlinear constraints during presolve (nonlinear part was not copied)
5068
5069- Heuristics:
5070 - fixed wrong solving status (OPTIMAL) in case an unbounded solution was provided or found by heuristic before presolve
5071 - fixed bug in heur_subnlp running with tightened tolerances: sumepsilon must be tightened like feastol and epsilon
5072 - fixed bug in nlp diving heuristic for fractional variables with values slightly outside of their domain
5073
5074- Numerics:
5075 - fixed several numeric issues
5076 - fixed numerical bug in conflict.c relaxing bounds while keeping an infeasibility proof
5077 - fixed feasibility decision bug when replacing inactive variables by their active counterparts, which might change the
5078 redundancy status of a bounddisjunction constraint due to numerics
5079 - fixed numerical bug adding a relaxed bound for conflict analysis in cons_varbound
5080 - fixed numerical bug in conflict analysis of genvbounds propagator
5081
5082@section RN300 SCIP 3.0.0
5083*************************
5084
5085Features
5086--------
5087
5088- SCIPcomputeLPRelIntPoint() with normtype=`s` now uses homogenized LP for computing rel.int. point too and allow to
5089 set relaxrows = FALSE
5090- new column showing the pseudo objective value
5091- digraph structure added to misc.c and pub_misc.h that can be used to handle directed graphs, compute undirected
5092 components in the graph and sort these components (almost) topologically
5093- SCIP does now print an info message when the root LP could not be solved or is unbounded
5094- added counter and clock for SCIPcopy() calls
5095- correct initialization of steepest edge weights with SoPlex 1.6.0.4
5096- parameters can now be fixed, which means that their value cannot be changed unless they are unfixed, first;
5097 the fixing status of a parameter is copied to sub-SCIPs, which allows to ensure that certain parameters
5098 are also not changed when, e.g., heuristics change emphasis settings or also specific parameters
5099- automatic transfer of original solutions (e.g., provided by the user, from solution pool, after restart, from heuristic
5100 adding original solution during solve) to the transformed space (might fail due to, e.g., dual fixings)
5101- added possibility to use GUBs for lifting knapsack cuts (disabled)
5102- added pre- and post-conditions in doxygen documentation for all methods of scip.{c,h}
5103- added zeroobj heuristic that solves a copy of the problem without an objective function and with quite strict limits
5104 on the number of nodes and LP iterations
5105- complete reworking of the vbounds propagator: it now takes into account variable bounds, cliques and implications,
5106 stores bounds of variables which were changed and performs a forward propagation from these bounds, i.e., tries to
5107 derive new bounds for other variables; during propagation, bound changes are propagated in an (almost) topological order
5108
5109- Constraints:
5110 - full version of cumulative constraint handler
5111 - new constraint handler `superindicator` for indicator constraints with slack constraints of arbitrary type
5112 - implemented first clique lifting procedure in cons_setppc.c (by default is off)
5113 - the conjunction and disjunction constraint handlers are now able to parse their CIP output format
5114
5115- Memory:
5116 - better handling of memory limits, in particular for large problems
5117 - estimate memory consumption for sub-SCIP and do not copy them if close to memory limit
5118
5119- Presolve:
5120 - time for initpre and exitpre methods is now also measured in presolving time
5121 - added dual presolving for and-constraints difficult instances (no guarantees)
5122 - oneopt can now be called before presolving
5123 - added a presolving step in the disjunctive constraint handler, removing disjunction, where a sub-constraint was
5124 deleted, which means this sub-constraint is redundant, which again means it is always TRUE or will be enforced by
5125 another constraint
5126 - added new presolver convertinttobin, which converts bounded integer variables to their binary representation, e.g.
5127 for integer variable 0 <= x <= 10 the binary variables y0, y1, y2 and y3 are created, such that
5128 1 y0 + 2 y1 + 4 y2 + 8 y3 <= 10 and x = 1 y0 + 2 y1 + 4 y2 + 8 y3
5129 - added new presolver gateextraction, which tries to find and-gates/constraints which are linearized
5130 e.g. (x + y + z >= 1, x + y <= 1 and x + z <= 1 => x == AND(~y,~z)), in special cases it also detects set-partitioning
5131 constraints e.g. (x + y + z >= 1, x + y <= 1, x + z <= 1 and y + z <= 1 => x + y + z == 1));
5132 gate-extractor is also able to detect logicor constraints and set-packing/-partitioning constraints with the same
5133 variables, to upgrade these both constraints to a set-partitioning constraint
5134 - added new presolver components, that searches for independent components in the problem structure and solves
5135 these components as sub-SCIPs when they are small enough (per default <= 20 discrete variables, nodelimit of 10000)
5136 - added new presolver domcol that looks for dominated columns in a MIP and tries to fix them
5137
5138- Reader:
5139 - CNF reader now creates feasibility instances per default, usage of an objective has to be set by a parameter
5140 - added reader for MI(NL)Ps in OSiL (Optimization Services Instance Language) format
5141
5142- Statistic:
5143 - new statistics and new statistic output messages
5144 - number of presolving calls of plugins is counted and displayed in the statistics,
5145 can be accessed via SCIPpresolGetNCalls() and SCIP{prop/conshdlr}getNPresolCalls()
5146 - the statistics shows for a branching rule the number of calls for LP, extern and pseudo candidates
5147 - new switch `SCIP_STATISTIC` and new macros SCIPstatisticMessage(), SCIPstatisticPrintf() and SCIPstatistic() to output
5148 statistic and execute code lines which are only needed therefor. Works as `SCIP_DEBUG` and SCIPdebugXyz()
5149 - added statistics on the number of cuts/rows that have actually been applied to the lp for each constraint handler and separator;
5150 use SCIPcreate(Empty)RowCons() and SCIPcreate(Empty)RowSepa() to support the statistics.
5151
5152- NLP:
5153 - new propagators obbt and genvbounds for MINLP
5154 - new NLPI parameter `SCIP_NLPPAR_FASTFAIL` to enable convergence checks in NLP solver to stop early on seemingly
5155 - added nlpdiving heuristic that comprises several diving heuristics using an NLP relaxation
5156
5157Performance improvements
5158------------------------
5159
5160- improved scaling by choosing the smallest scaler
5161- if first root lp is solved and the optimality is rejected by SCIP, there won't be an unnecessary solving of the lp
5162 from scratch again
5163- several performance improvements for Pseudo-Boolean optimization, pseudo objective propagator
5164- streamlined initlp functions in cons_indicator, cons_sos1, cons_sos2 (add rows only if needed)
5165- improved time used for adding implications
5166- speed up in SCIPboolarrayExtend() in misc.c replacing a for loop with BMSmoveMemoryArray() call
5167- speed up in var.c changing some recursive calls into iterative calls and reducing the number of VARFIX event that are
5168 thrown for fixation, aggregation or multi-aggregations
5169- revised reduced cost propagator
5170- increased performance in SCIPcliqueAddVar(), adding a variable to a clique
5171- tighten primal and dual feasibility tolerances independently if they are not reached in LP solving
5172
5173- Probing:
5174 - if probing reached the end of all variables it will restart the probing cycle correctly
5175 - improved probing by ordering the variables differently and applying the one-branch before the zero-branch
5176
5177- Constraints:
5178 - improved scaling of linear constraints, linear constraints with integral variables will now be scale with
5179 1e+06/MAX(maximal absolute coefficient, 1.0) instead of 1e+03/MAX(maximal absolute coefficient, 1.0);
5180 if all coefficients are in absolute value equal they will be scaled by that
5181 - added clique presolving for and-constraints, which checks if two operands or one operand and the resultant are in a
5182 clique and then fixes the resultant to 0 and in the former case we can delete the and-constraint too
5183 - speed up in linear constraint handler replacing aggregated variables
5184 - when all nonlinearities have been fixed and the number of nonfixed variables is 1 in cons_nonlinear/cons_quadratic/
5185 cons_bivariate, handle it by a bound change instead of adding a linear constraint
5186
5187- Separation:
5188 - automatically turn off separation in sepa_oddcycle if it was too unsuccessful within the last calls
5189 - use faster Dijkstra variants in sepa_oddcycle
5190 - improved tcliquegraphAddImplicsVars() in sepa_clique.c to faster add possible variables
5191 - changed emphasis settings: knapsack disaggregation is now allowed in fast presolving, CG-MIP separator disabled in
5192 aggressive separation
5193
5194- Reader:
5195 - improved lp-, mps-, opb-reading time
5196 - speed up mps reader asking parameters only once
5197
5198- Heuristics:
5199 - added parameters mincoveredrel and mincoveredabs to heur_undercover to only run if problem is sufficiently nonlinear
5200 - improved intdiving heuristic by activating backtracking to a different fixing value
5201 - heur_undercover treats indicator constraints as nonlinear and fixes the binary variable for linearization
5202
5203Examples and applications
5204-------------------------
5205
5206- new examples for scheduling and usage of the callable library with nonlinear problems
5207- the error messages are not handled via the message handler anymore; per default the error message a written to stderr
5208
5209Interface changes
5210-----------------
5211
5212- introduced basic inclusion and creation methods to simplify usage of the SCIP library
5213- allowed to start diving mode even if LP is not flushed, not solved, or not solved to optimality
5214- changed the message handler system within SCIP heavily such that it is thread save
5215- the resolve propagation methods for the constraint handler and propagator getting a new parameter called relaxedbd;
5216 explaining/resolving this relaxed bound is sufficient
5217- default integer comparer SCIPsortCompInt() (see pub_misc.h)
5218
5219- LP interface:
5220 - SoPlex LPI supports setting of `SCIP_LPPAR_DUALFEASTOL` when using SoPlex version 1.6.0.5 and higher.
5221
5222- Problem:
5223 - Forbid problem modifications in `SCIP_STAGE_{INIT,EXIT}PRESOLVE` (see pre-conditions for corresponding methods in scip.h).
5224
5225- Miscellaneous:
5226 - New macro SCIPdebugPrintCons() to print constraint only if `SCIP_DEBUG` flag is set.
5227 - all objscip *.h file now use the default SCIP interface macros (this should avoid errors when changing the interface)
5228
5229### New and changed callbacks
5230
5231- Constraint Handler:
5232 - Added a propagation timing parameter `proptiming` to SCIP_DECL_CONSPROP(), giving the current timing at which
5233 this method is called (also to the corresponding c++ wrapper classes).
5234 - New optional callback methods in constraint handlers: `SCIP_DECL_CONSGETVARS` and `SCIP_DECL_CONSGETNVARS`.
5235 These callbacks, if implemented, should return an array of all variables and the number of all variables used
5236 by the given constraint, respectively. (This method might, e.g., be called by a presolver)
5237
5238- NLP Solver Interface:
5239 - New NLPI callback SCIP_DECL_NLPISETMESSAGEHDLR() to set message handler in NLP solver interfaces.
5240
5241- Propagator:
5242 - Added a propagation timing parameter `proptiming` to SCIP_DECL_PROPEXEC(), giving the current timing at which this method is
5243 called (also to the corresponding c++ wrapper classes).
5244
5245- Plugin management:
5246 - added `basic` inclusion methods which have only fundamental data of the plug-ins as arguments; added setter functions
5247 for all non-fundamental callbacks of the plug-ins; the plug-in types with basic inclusion functions are:
5248 readers, constraint handlers, conflict handlers, presolvers, propagators, heuristics, separators, relaxation handlers,
5249 branching rules, node selectors and pricers; these methods should make the usage easier, sparing out optional callbacks and
5250 parameters: e.g., SCIPincludeConshdlrBasic();
5251 - To extend the basic functionalities, there are setter method to add
5252 optional callbacks. For example SCIPsetConshdlrParse(), SCIPsetPropCopy() or SCIPsetHeurInitsol().
5253
5254- Constraint Handlers:
5255 - Added basic creation methods for all constraints types, e.g., SCIPcreateConsBasicLinear(); these methods should make the usage easier,
5256 sparing out optional callbacks and parameters.
5257
5258### Deleted and changed API methods
5259
5260- SCIPcomputeCoverUndercover() now has an additional parameter coverbd
5261- tcliqueMaxClique has an additional parameter to store the number of used branch-and-bound nodes
5262- the code in `src/dijkstra` and `src/xml` has been changed to (increasingly) conform to the SCIP coding style;
5263 all function (and variable) names have been changed (do not contain `_` anymore).
5264- renamed SCIPstairmap*Core() to SCIPstairmap*Stair()
5265
5266- Conflict Analysis:
5267 - Added parameter `relaxedbds` to conflict handler callback method SCIP_DECL_CONFLICTEXEC(). This array contains
5268 bounds which are sufficient to create a valid conflict
5269
5270- Constraint Handler:
5271 - Added a parameter `restart` to the SCIP_DECL_CONSEXITSOL() callback method, indicating whether this call was
5272 triggered by a restart.
5273 - Added a parameter `relaxedbd` to SCIP_DECL_CONSRESPROP() callback method. If explaining a given bound change
5274 (index), it is sufficient to explain the reason for reaching the `relaxedbd` value, see above
5275 - Removed parameters `isunbounded`, `isinfeasible` and `result` from SCIP_DECL_CONSINITPRE() and SCIP_DECL_CONSEXITPRE()
5276 callback methods. It is not allowed to determine unboundedness or infeasibility in these callbacks, anymore.
5277 - added a `SCIP_CONS*` parameter to SCIPcreateConsDisjunction() which can represent the linear relaxation of the whole
5278 disjunction constraint as a conjunction constraint, or `NULL`
5279 - remove problematic function cons_indicator:SCIPsetSlackVarIndicator()
5280 - Renamed SCIPgetCountedSparseSolutions() to SCIPgetCountedSparseSols() in cons_countsols.{c,h}.
5281
5282- Counting:
5283 - Changed the counting system within SCIP heavily. New method for `SCIP_SPARSESOL` usage, SCIPsparseSolCreate(),
5284 SCIPsparseSolFree(), SCIPsparseSolGetVars(), SCIPsparseSolGetNVars(), SCIPsparseSolGetLbs(), SCIPsparseSolGetUbs()
5285 in (pub_)misc.{c,h}.
5286
5287- Cuts and Separation:
5288 - removed `targetscip` parameter from SCIPconvertCutsToConss(), now this function can only convert cuts on one instance,
5289 otherwise use SCIPcopyCuts()
5290 - added `ncutsadded` parameter to SCIPcopyCuts() to be able to store the number of copied/converted cuts
5291 - New functions SCIPcreateEmptyRowCons(), SCIPcreateEmptyRowSepa(), SCIPcreateRowCons(), and SCIPcreateRowSepa() that allow
5292 to set the originating constraint handler or separator of a row respectively; this is, for instance, needed for statistics
5293 on the number of applied cuts. If rows are created outside a constraint handler or separator use SCIPcreateRowUnspec() and
5294 SCIPcreateEmptyRowUnspec(). The use of SCIPcreateEmptyRow() and SCIPcreateRow() is deprecated.
5295 - New functions SCIProwGetOrigintype(), SCIProwGetOriginCons(), and SCIProwGetOriginSepa() to obtain the originator
5296 that created a row.
5297
5298- LP:
5299 - new parameter numerics/lpfeastol for primal feasibility tolerance used in LP solver
5300 - SCIPcomputeLPRelIntPoint() takes two new arguments giving a time and iteration limit
5301 - SCIPcolGetStrongbranchLPAge(), SCIPgetVarStrongbranchLPAge(), SCIPgetNLPs(), SCIPgetNPrimalLPs(), SCIPgetNDualLPs(),
5302 SCIPgetNBarrierLPs(), SCIPgetNResolveLPs(), SCIPgetNPrimalResolveLPs(), SCIPgetNDualResolveLPs(), SCIPgetNNodeLPs(),
5303 SCIPgetNNodeInitLPs(), SCIPgetNDivingLPs(), SCIPgetNStrongbranchs(), SCIPgetNRootStrongbranchs() now return a longint
5304 instead of an integer
5305
5306- Message Handler and Printing:
5307 - New callback method SCIP_DECL_MESSAGEHDLRFREE() which is called when the message handler is freed.
5308 - The old callback method SCIP_DECL_MESSAGEERROR() was replaced by the callback method SCIP_DECL_ERRORPRINTING().
5309 - the follwing methods additionally need the SCIP pointer as parameter to make the output thread save:
5310 SCIPprintVersion(), SCIPsetMessagehdlr(), SCIPgetMessagehdlr() and SCIPwarningMessage()
5311 - the error printing method can be replaced using the method SCIPmessageSetErrorPrinting(); the default error message
5312 printing can be recoverd via SCIPmessageSetErrorPrintingDefault() (see pub_message.h)
5313 - Changed the message handler system within SCIP heavily such that it is thread-safe. SCIPcreateMessagehdlr() in
5314 scip.{c,h} was replaced by SCIPmessagehdlrCreate() in pub_message.h/message.c with a changed parameter list;
5315 see pub_message.h and type_message.h.
5316 - removed method SCIPcreateMesshdlr(), please use SCIPmessagehdlrCreate() (see pub_message.c)
5317 - removed method SCIPfreeMesshdlr(), please use SCIPmessagehdlrRelease() (see pub_message.c)
5318 - Error messages (SCIPerrorMessage()) are not handled via the message handler anymore; per default the error
5319 message is written to stderr.
5320 - the following methods need an additional message handler: SCIPdispLongint(), SCIPdispInt(), SCIPdispTime(), all message
5321 handler methods (see pub_message.h), SCIPhashtablePrintStatistics(), SCIPhashmapPrintStatistics(), SCIPlpiCreate()
5322 - SCIPprintCons() does not print termination symbol `;\n` anymore; if wanted, use SCIPinfoMessage() to print `;\n` manually
5323 - remove SCIPcolPrint() and SCIProwPrint(), please use SCIPprintCol() SCIPprintRow() see scip.h
5324 - method SCIPprintError() does not need the file stream anymore. The error is written via the error message callback.
5325
5326- Nonlinear expressions, relaxation, and solver interface:
5327 - Method SCIPexprtreeRemoveFixedVars() is not public anymore.
5328 - Renamed SCIPmarkNonlinearitiesPresent() to SCIPenableNLP()
5329 - Renamed SCIPhasNonlinearitiesPresent() to SCIPisNLPEnabled().
5330 - removed SCIPmarkContinuousNonlinearitiesPresent(),
5331 renamed SCIPhasContinuousNonlinearitiesPresent() to SCIPhasNLPContinuousNonlinearity() and allow call only during
5332 initsolve and solve,
5333
5334- Parameters:
5335 - Replaced SCIPparamSet*() by SCIPchg*Param()
5336 + replaced SCIPparamSetBool() by SCIPchgBoolParam()
5337 + replaced SCIPparamSetInt() by SCIPchgIntParam()
5338 + replaced SCIPparamSetLongint() by SCIPchgLongintParam()
5339 + replaced SCIPparamSetReal() by SCIPchgRealParam()
5340 + replaced SCIPparamSetChar() by SCIPchgCharParam()
5341 + replaced SCIPparamSetString() by SCIPchgStringParam()
5342
5343- Presolving:
5344 - Removed parameters `isunbounded`, `isinfeasible` and `result` from SCIP_DECL_PRESOLINITPRE() and
5345 SCIP_DECL_PRESOLSEXITPRE(). It is not allowed to determine unboundedness or infeasibility in these callbacks, anymore.
5346
5347- Propagator:
5348 - changed parameters of function SCIPpropagateCutoffboundVar() in prop_pseudoobj.{c,h}
5349 - Added a parameter `restart` to SCIP_DECL_PROPEXITSOL() callback method, indicating whether this call was triggered
5350 by a restart.
5351 - Added a parameter `relaxedbd` to SCIP_DECL_PROPRESPROP() callback method. If explaining a given bound change
5352 (index), it is sufficient to explain the reason for reaching the `relaxedbd` value.
5353 - Removed parameters `isunbounded`, `isinfeasible` and `result` from SCIP_DECL_PROPINITPRE() and
5354 SCIP_DECL_PROPEXITPRE() callback methods. It is not allowed to determined unboundedness or infeasibility in
5355 these callbacks, anymore.
5356
5357- Sort and Copy:
5358 - The methods SCIPsortedvecInsert*() have an additional parameter which can be used to receive the position where
5359 the new element was inserted, if this is not of interest a `NULL` pointer can be given
5360 - new parameter in SCIPcopyPlugins() to indicate whether the message handler from the source SCIP should be passed to the
5361 target SCIP (only the pointer is copied and the usage counter of the message handler is increased)
5362 - New parameter in SCIPcopy() to indicate whether the message handler from the source SCIP
5363 should be passed to the target SCIP (only the pointer is copied and the usage counter of the message handler is
5364 increased). In multi theaded enviroment this parameter needs to be set to FALSE.
5365
5366- Variable usage:
5367 - rename SCIPvarGetBestBound() to SCIPvarGetBestBoundLocal()
5368 - rename SCIPvarGetWorstBound() to SCIPvarGetWorstBoundLocal()
5369 - Method SCIPvarGetProbvarSum() is not public anymore, use SCIPgetProbvarSum() instead.
5370 - Replaced method SCIPvarGetRootRedcost() by SCIPvarGetBestRootRedcost().
5371
5372### New API functions
5373
5374- setup timer to all plugins and therefore SCIP<plugin-type>GetSetupTime() methods in all pub_plugin-type.h to ask
5375 for this time (, e.g. SCIPeventhdlrGetSetupTime() in pub_event.h)
5376- new GML(Graph Modeling Language) methods SCIPgmlWriteOpening(), SCIPgmlWriteCosing(), SCIPgmlWriteArc(), SCIPgmlWriteEdge(),
5377 SCIPgmlWriteNode() that write to a given GML file
5378- new LPI method SCIPlpiGetObjsen() to query objective sense
5379- SCIPpermuteIntArray() in pub_misc.h and misc.c for permuting an integer array
5380- SCIPcalcBinomCoef() in pub_misc.h and misc.c which calculates a binomial coefficient up to 33 over 16
5381- SCIPheurPassSolAddSol() in heur_trysol.c; solution which are passed via this method are just without any feasibility check
5382- SCIPgetGlobalPseudoObjval() which returns the global pseudo objective value which is all variables
5383 set to their best (w.r.t. the objective function) global bound
5384- SCIPhashGetKeyStandard() which returns the element itself as the key, SCIPhashKeyEqPtr(),
5385 SCIPhashKeyValPtr() which do the hash-comparison/-conversion on a pointer in pub_misc.h
5386- SCIPhashtableClear() which removes all elements of a hash table
5387- SCIPisUpdateUnreliable() to check whether an iteratively updated value should be recomputed from scratch
5388 (e.g., for activities; uses new parameter `misc/num_recompfac`)
5389- SCIPisHugeValue() to check whether a value is huge and should be handled separately from other values
5390 (e.g., in activity computations) and SCIPgetHugeValue() to get the smallest value counting as huge
5391- SCIPfixParam() and SCIPunfixParam() to fix and unfix a parameter, respectively;
5392 the fixing status of a parameter can be requested by SCIPparamIsFixed();
5393- SCIPsetBasePointClosecuts() to set the base point for close cut separation
5394- SCIPchgCutoffboundDive() to change the cutoffbound in diving mode
5395- SCIPupdateCutoffbound() which can be used to pass a cutoff bound
5396
5397- Presolving:
5398 - SCIPpropIsPresolDelayed() which return if a propagator is delay during presolving
5399 - Added method SCIPisPresolveFinished() which returns whether the presolving process would be stopped after the
5400 current presolving round, given no further reductions will be found, can be used to ensure that a presolver is called very late
5401
5402- Memory:
5403 - added forgotten implementation of SCIPfreeMemorySize(), SCIPfreeMemorySizeNull() in scip.h and BMSfreeMemorySize(),
5404 BMSfreeMemorySizeNull() in memory.h
5405 - SCIPmemccpy() in pub_misc.h and misc.c which copies either a specified number of charcters of a source
5406 string to a destination string or until it hits a stoping character
5407 - BMSmoveMemory(), BMSmoveMemoryArray(), BMSmoveMemorySize() and corresponding BMSmoveMemory_call() in
5408 memory.{h,c} too move memory elements
5409
5410- Conflict Analysis:
5411 - SCIPisConflictAnalysisApplicable() which return FALSE is the conflict will not runs; can be used
5412 to avoid unnecessary initialization of the conflict analysis
5413 - SCIPaddConflictRelaxedLb(), SCIPaddConflictRelaxedUb() and SCIPaddConflictRelaxedBd(); these methods
5414 can be used to give for a bound change which is part of an explanation a relaxed bound; this means the relaxed bound
5415 is already efficient to be part of a valid explanation
5416 - SCIPisConflictVarUsed() returns TRUE if the given bound change is already part of the conflict set;
5417 that is the bound change is redundant;
5418 - SCIPgetConflictVarLb() and SCIPgetConflictVarUb() returning the lower/upper bound of the given
5419 variable within the current active conflict set
5420
5421- Variable usage:
5422 - SCIPvarsGetProbvar() in pub_var.h and var.c, which returns for a given array of variables the active, fixed
5423 or multiaggregated representation
5424 - SCIPgetActiveVars() in scip.{h,c}, which returns for a given array of variables the active counterparts
5425 - SCIPgetNObjVars() which returns the number of variables which have a non-zero objective coefficient
5426 - SCIPenableVarHistory() and SCIPdisableVarHistory() which can be used to turn off and on the collection
5427 of variables statistics which is used for example for branching
5428 - SCIPbranchVarHole() which branches a variable w.r.t. a given domain hole
5429 - SCIPvarGetAggregatedObj() which computes for a (not active) variable the corresponding objective value
5430 - SCIPsolIsOriginal() that returns whether a solution is defined on the original variables
5431 - SCIPgetVarImplRedcost() which returns the implied reduced costs
5432 - SCIPvarGetBestRootSol(), SCIPvarGetBestRootRedcost(), SCIPvarGetBestRootLPObjval() which return the best
5433 combination for a variable w.r.t. root solution value, root LP objective value and root reduced cost
5434 - SCIPhaveVarsCommonClique() in scip.{h,c}, to check for common clique information on two given variables
5435 - added basic creation methods SCIPcreateVarBasic() and SCIPcreateProbBasic() and setter functions for
5436 non-fundamental callbacks of variables and problems.
5437 - added new methods SCIPvarGetBestBoundGlobal() and SCIPvarGetWorstBoundGlobal().
5438
5439- Constraint Handler:
5440 - added public wrapper functions for calling constraint handler callback methods for a single constraint:
5441 SCIPactiveCons(), SCIPdeactiveCons(), SCIPinitlpCons(), SCIPsepalpCons(), SCIPsepasolCons(), SCIPpropCons(),
5442 SCIPrespropCons(), SCIPenfopsCons(), SCIPenfolpCons()
5443 - added basic creation methods for all constraint handlers
5444 - SCIPchgCapacityKnapsack() which can be used to change the capacity of a knapsack constraint
5445 - SCIPconsIsAdded() which returns whether a constraint was already to a SCIP instance
5446 - SCIPconshdlrGetNCutsApplied() in pub_cons.h to get the number of cuts applied to the lp
5447 - SCIPconshdlrIncNAppliedCuts() in cons.h to increase the number of applied cuts (used by sepastore.c)
5448 - SCIPchgVarName() and SCIPchgConsName() which can be used to change name of variables and
5449 constraints in problem creation stage
5450 - New methods SCIPgetConsVars() and SCIPgetConsNVars() which return for a given constraint the involved variables and
5451 the number of variables if the corresponding constraint supports this (optional) callbacks
5452 (corresponding callbacks need to be implemented, see above)
5453
5454- Message Handler:
5455 - SCIPmessagehdlrCapture() which captures a given message handler (increases number of uses)
5456 - SCIPmessagehdlrRelease() which releases and possibly frees a given message handler (decreases number of uses)
5457 - SCIPsetMessagehdlrLogfile() which can be used to write into a log file
5458 - SCIPsetMessagehdlrQuiet() which can be used to turn the screen output on and off
5459
5460### Command line interface
5461
5462- in the interactive shell, parameters can be fixed and unfixed with `fix` (instead of `set`), e.g., `fix heuristics rens freq TRUE`;
5463- new shell command `change minuc` to minimize the number of unsatisfied constraints
5464
5465### Interfaces to external software
5466
5467- beta-version of a MATLAB interface can be found under interfaces/matlab
5468- beta-version of a AMPL interface can be found under interfaces/ampl
5469
5470### Changed parameters
5471
5472- `branching/fullstrong/reevalage` changed from an integer to a longint parameter
5473
5474- Removed parameters:
5475 - `separating/closecuts/separootonly`
5476 - `constraints/quadratic/defaultbound`
5477 - `separating/cgmip/nodelimit`
5478
5479### New parameters
5480
5481- `constraints/%s/timingmask` for changing the timingmask for calling the propagtion method of all constraint plugins
5482- `constraints/and/dualpresolving` by default set to TRUE, enabling dual-presolving on and-constraints
5483- `constraints/indicator/{sepacouplingcuts,sepacouplinglocal}` to enable separation of (local) cuts
5484- `constraints/indicator/{maxsepacuts,maxsepacutsroot}` to restrict the number of separated cuts
5485- `constraints/indicator/dualreductions` to enable dual presolving/propagation steps
5486- `constraints/setppc/cliquelifting`, `constraints/setppc/addvariablesascliques`,
5487 `constraints/setppc/cliqueshrinking`, first for enabling/disabling the clique lifting algorithm in cons_setppc.c,
5488 second parameter is for trying to create extra clique constraints in lifting algorithm, third parameter is for trying
5489 to decrease the number of variable in a clique constraint in the lifting algorithm
5490- `limits/totalnodes` that allows to stop at the correct node if a restart occured; therefore the new
5491 `SCIP_STATUS_TOTALNODELIMIT` is added
5492- `lp/{rootiterlim,iterlim}` to set a limit on the LP iterations spend in the initial root LP and each
5493 LP resolve, respectively
5494- `misc/transorigsols` by default set to TRUE, that switches whether SCIP tries to transfer original
5495 solutions into the transformed space (in initsol and if a heuristic adds an original solution during solving)
5496- `numerics/hugeval` that defines the smalles value counting as huge (see new method SCIPisHugeValue())
5497- `numerics/recompfac` which denotes the factor, by which the absolute of an iteratively updated value has
5498 to be decreased in order to recompute the value from scratch
5499- `presolving/convertinttobin/maxdomainsize` by default is set to `SCIP_LONGINT_MAX`, which deternmines
5500 the domainsize for which integers are converted to their binary representation
5501- `presolving/convertinttobin/onlypoweroftwo` by default is set to FALSE, that parameter allows you to
5502 only convert integer variables with a domainsize of 2^p-1 to their binary representation
5503- `presolving/convertinttobin/samelocksinbothdirections` by default is set to FALSE, that parameter allows
5504 you to convert only integer variables to their binary representation, which have the same amount of up- and downlocks
5505- `presolving/gateextraction/sorting` by default is set to 1, that parameter determines if you want to try
5506 to extract big-gates(-1) or small-gates(1) at first by ordering bigger/smaller logicor constraint up front, or use
5507 them as they are (0)
5508- `presolving/gateextraction/onlysetpart` by default is set to FALSE, that parameter allows you to
5509 only extract set-partitioning and no and-constraints
5510- `presolving/gateextraction/searchequations` by default is set to TRUE, that parameter allows you to
5511 search for logicor constraints and set-packing/-partitioning constraints with same variables
5512- `propagating/%s/timingmask` for changing the timingmask for calling the propagtion method of all propagator plugins
5513- `propagating/probing/maxdepth` to set the maximal depth until the probing propagation is executed
5514- `reading/cnfreader/useobj` to state whether an artificial objective, depending on the number of clauses
5515 a variable appears in, should be used, by default set to FALSE, old default behavior of reader corresponds to TRUE
5516- `separating/cgmip/{minnodelimit,maxnodelimit}` to determine node limit.
5517- `separating/closecuts/maxlpiterfactor` for iteration limit in relative interior point computation
5518- `separating/oddcycle/maxunsucessfull` to automatically turn off separation
5519- `oncepernode` in Rounding and Simple Rounding heuristic
5520
5521### Data structures
5522
5523- new data structure for binary trees (`SCIP_BT` and `SCIP_BTNODE` in pub_misc.h)
5524- renamed data structure `SCIP_STAIRMAP` to `SCIP_PROFILE`
5525- added new stages `SCIP_STAGE_INITPRESOLVE`, `SCIP_STAGE_EXITPRESOLVE` and `SCIP_STAGE_FREE`; renamed `SCIP_STAGE_FREESOLVE`
5526 to `SCIP_STAGE_EXITSOLVE`
5527- Changed the counting system within SCIP heavily. `SPARSESOLUTION` was renamed to `SCIP_SPARSESOL` and moved
5528 from cons_countsols.h to struct_misc.h
5529
5530Testing
5531-------
5532
5533- the check script now recognizes MIQCP and MINLP instances
5534- make test now also checks instances in wbo, cnf, osil and fzn format
5535- renamed parameter SCRDIR of `make testgams` to CLIENTTMPDIR and changed its default to `/tmp`
5536
5537Build system
5538------------
5539
5540### Makefile
5541
5542- CppAD source code is now distributed with SCIP (`src/cppad`), so that `lib/cppad` is not used anymore;
5543 the default for EXPRINT has changed from none to cppad
5544
5545Fixed bugs
5546----------
5547
5548- fixed bug with strong branching with the LP status for conflict analysis
5549- fixed bug w.r.t. adding a value to the objective offset of the transformed problem
5550- fixed wrong assert in feasibility pump stage 3
5551- fixed bug in solve.c, applied bounding for the initial lp was only done if root-lp-solution was valid but another
5552 solution could also have been added
5553- primal solutions with infinite objective value are now automatically discarded
5554- all plugins that solve sub-SCIPs now do not stop the whole solution process if there has been an error
5555- fixed bug in cip reader, wrong use of SCIPstrtok()
5556
5557- Variables:
5558 - fixed bug in shiftandpropagate w.r.t. SCIPconstructLP() which can have the side effect that variables are created
5559 - method SCIPvarGetProbvarSum() (and thus also SCIPgetProbvarSum()) returns +/-infinity if the variable resolves to a
5560 variable fixed to +/-infinity (depending on the sign of the scalar) but does not multiply with the scalar, anymore
5561 - better handling of infinite solution values for aggregated and negated variables
5562 - fixed bug that disabled multi-aggregation of two integer or implicit integer variables
5563 - fixed bug in sol.c with requesting values of transformed variables in original solution; previously this had only
5564 been handled in SCIPgetSolVal(), now the handling has been moved to SCIPsolGetVal()
5565 - fixed several bugs writing an mps file in the reader_mps.c, e.g. writing fixed variables which are not (yet) removed
5566 and writing integer variables even with an objective value of 0, if they only exist in non-linear constraints
5567
5568- Separation:
5569 - fixed minor bugs with respect to counting generated and lifted cuts in sepa_oddcycle
5570 - fixed bug in sepa_clique.c, could not handle only empty cliques, that were not removed
5571
5572- Heuristics:
5573 - fixed potential bugs in shiftandpropagate heuristic concerning the transformation update of a variable with free status
5574 - fixed bug in heur_zirounding with computation of up/downslacks
5575 - fixed bug in mutation heuristic with unnecessary aborts due to a wrong memory limit
5576 - fixed potential bug in fix-and-infer heuristic with variables being fixed to infinite value
5577 - fixed bug in diving heuristics with variables being fixed to values outside their domain
5578 - fixed bug in simple rounding heuristic with column generation for variables with strictly positive lower bound
5579 - made Octane heuristic numerically more stable to avoid asserts being caused by cancellation
5580 - fixed bug in mutation heuristic with variables being fixed to infinite values
5581 - do not run heur_shiftandpropagate if there is no LP
5582
5583- LP Interface:
5584 - fixed bug in Cplex LPI: after running simplex, solisbasic flag was always true, which might be wrong if Cplex hit a
5585 time limit
5586 - fixed bug in SCIP probing mode with cleared LPI state but solved LP
5587 - fixed assert with `LPI=none` (need to count rows/cols in lpi_none)
5588 - fixed bug in SoPlex LPI where objective sense was not correct after reading LP from file in SCIPlpiReadLP()
5589
5590- Constraints:
5591 - fixed bug in scip.c adding a constraint in SCIPgetConsCopy() to the constraint hashmap
5592 - fixed bug in cons_linear w.r.t recalculation of unreliable activities
5593 - fixed bug in cons_linear concerning huge activity values: besides infinite contributions, we now also treat huge
5594 contributions separately, count their occurences in a constraint and provide a relaxed activity value
5595 - fixed bug in cons_xor.c parsing a constraint
5596 - fixed count of propagations in cons_indicator and only try to propagate if variables are not yet fixed
5597 - fixed some bugs in cons_disjunction.c (wrong assert, forgotten deletion of constraint, wrong SCIPreleaseCons() call)
5598
5599Miscellaneous
5600-------------
5601
5602- first release of GCG, a generic branch-cut-and-price solver built on top of SCIP
5603- first release of UG, a framework for solving mixed integer programs, mixed integer
5604 nonlinear programs and constraint integer programs in parallel
5605- new SCIP T-shirts
5606- renamed ZIB Optimization Suite to SCIP Optimization Suite
5607
5608@page RN21 Release notes for SCIP 2.1
5609
5610@section RN212 SCIP 2.1.2
5611*************************
5612
5613Performance improvements
5614------------------------
5615
5616- fixed performance issue in debug mode, where SCIPvarGetLPSol_rec() calculated a value to often, which in the end lead
5617 to exponential growth in running time
5618- force cuts from linearizations of convex constraint in NLP relax solution into LP, thus allowing faster proving of
5619 optimality for convex NLPs
5620
5621Fixed bugs
5622----------
5623
5624- fixed bug in varAddTransitiveImplic() in var.c, when adding implications on special aggregated, namely negated, variables
5625- fixed issue if a primal solution leads to a cutoff of the current focus node
5626- fix compilation issues with zlib 1.2.6
5627- fixed bug in SCIPsolveKnapsackExactly(), trying to allocate too much memory which led to an overflow and later to a segmentation fault
5628- fixed bug in sepa_rapidlearning, carrying on the optimization process, when already solved
5629
5630- Heuristics:
5631 - fixed bug in heur_undercover.c, where a variable with fixed bounds but not of status `SCIP_VARSTATUS_FIXED` was wrongly handled
5632 - fixed bug in heur_oneopt.c which forgot to check LP rows if local rows are present
5633
5634- Constraints:
5635 - fixed bug in SCIPsolveKnapsackExactly()
5636 - fixed bug in cons_quadratic where bounds on activity of quadratic term were not always invalidated when quadratic variables were removed
5637 - fixed bug in cons.c, where after a restart the arrays for all initial constraints were corrected in the initsol process
5638 instead of the initpre process, this was to late because you might change the status in presolving which lead to an assert()
5639 - fixed bug in NLP representation of abspower constraints handling (x+a)^2 with nonzero a
5640 - fixed bug parsing an and-constraint in cip format
5641 - fixed bug in cons_setppc, did not handle new constraints with inactive variables
5642 - fixed bug in cons_xor.c which did not copy the artificial integer variable (used for the lp relaxation)
5643
5644@section RN211 SCIP 2.1.1
5645*************************
5646
5647Features
5648--------
5649
5650- the pseudo objective propagator can be forced to propagate if active pricers are present; this can be done
5651 if for all (known or unknown) variables follows that: they have positive (negative) objective coefficient
5652 and the global lower (upper) bound is zero.
5653
5654Performance improvements
5655------------------------
5656
5657- improvements in undercover heuristic
5658- improve SCIPintervalSolveBivariateQuadExpressionAllScalar() for ax=0 case if x has 0 in the interval for the linear coef.
5659- better domain propagation for quadratic constraints that consist of `non-overlapping` bilinear terms only
5660- ensure that a fixing of a variable in an abspower constraint is propagated to a fixing of the other variable
5661- improvements in undercover heuristic, e.g., bound disjunction constraints are considered when setting up the covering problem
5662
5663Interface changes
5664-----------------
5665
5666### Changed parameters
5667
5668- changed parameter `propagating/pseudoobj/maxcands` to `propagating/pseudoobj/minuseless` (see prop_pseudoobj.c)
5669 due to revision of the pseudo objective propagator
5670
5671### New parameters
5672
5673- added parameters `heuristics/undercover/coverbd` and `heuristics/undercover/fixingorder`
5674
5675Fixed bugs
5676----------
5677
5678- fixed numeric issue in aggregations
5679- fixed pseudo cost computation
5680- fixed bug with setting type of slack variables to be implicitly integral
5681- fixed bug when copying problem data in c++ case returned with the result `SCIP_DIDNOTRUN`
5682- fixed computation of counter which state the changes since the last call of a presolver
5683- fixed handling of unbounded solutions, including double-checking their feasibility and that the primal ray is a
5684 valid unboundedness proof and reoptimizing the LP with modified settings if the solution is not feasible
5685- fixed compilation issues with negate() function in intervalarith.c on exotic platforms
5686- fixed bug in SCIPsortedvecDelPos...() templates
5687- pseudo objective propagator does not propagate it active pricers are present
5688- fixed bug in heur_shiftandpropagate.c concerning the treatment of unbounded variables
5689- workaround for trying to add variable bounds with to small coefficients
5690
5691- Reading and Writing:
5692 - gams writer now also substitutes $-sign from variable/equation names
5693 - fixed bug in reader_mps.c: INTEND marker is now also written, if COLUMNS section ends with non-continous variables
5694 - fixed bug in flatzinc reader w.r.t. boolean expressions
5695
5696- Constraints:
5697 - fixed constraint flags evaluation within the ZIMPL reader (reader_zpl.c)
5698 - fixed bug in SCIPmakeIndicatorFeasible() in cons_indicator.c
5699 - fixed bug with conflict clause modification in cons_indicator
5700 - fixed bug in cons_bounddisjunction with uninitialized return values
5701 - fixed bug in cons_orbitope with calling conflict analysis
5702 - fixed bug in nlpi_oracle w.r.t. changing linear coefs in a NLP constraint
5703
5704@section RN210 SCIP 2.1.0
5705*************************
5706
5707Features
5708--------
5709
5710- New original solution storage capability, which allows transfering solutions between SCIP runs
5711- SCIP-CPX is now threadsafe
5712- comparison of solutions now also works for original solutions
5713- can now compute the relative interior point of the current LP
5714- interval arithmetics for power, log, exp, bivariate quadratic expressions should be rounding safe now
5715- LP iterations in resolving calls can now be limited w.r.t. the average number of LP iterations in previous calls
5716 (after the root node); this is currently only done for the initial LP solve at a node and the corresponding parameter
5717 resolveiterfac is set to -1 (no limit) per default
5718- it is now possible in `SCIP_STAGE_TRANSFORMED` to call SCIPaddVarLocks() (i.e. to lock variables in initialization methods)
5719- changed computation of optimality gap which is now done in the same way as described in the MIPLIB 2010 paper: the gap
5720 is 0, if primalbound (pb) and dualbound (db) are equal (within tolerances), it is infinity if pb and db have opposite
5721 signs and (this changed), if both have the same sign, the difference between pb and db is devided by the minimum of
5722 the absolute values of pb and db (instead of always the dual bound)
5723- functionality to use the bound flipping ratio test of SoPlex is available (requires at least version 1.5.0.7)
5724- there exists now a solution candidate store for the original problem; during transformation these solutions are tried;
5725 during free the transformed problem the best feasible solution of the transformed problem are copied to the solution
5726 candidate store of the original problem; this useful if you solve several problems iteratively, solutions get now
5727 carried over automatically.
5728- reworked concept of lazy bounds: they can now also be used for problems where constraints and objective together
5729 ensure the bounds; to allow this also for diving heuristics that might change the objective and thus destroy this
5730 property, lazy bounds are explicitly put into the LP during diving and removed afterwards
5731- `SCIP_HASHMAP` now works also without block memory
5732- The variable deletion event is now a variable specific event and not global, anymore.
5733- All timing flags are now defined type_timing.h.
5734- all C template files are now called <plugintype>_xyz.{c,h} instead of <plugintype>_xxx.{c,h}
5735
5736- Separators and Cuts:
5737 - reorganized computation of scores in cut filtering: instead of the computation at the time of addition, scores are now
5738 only computed w.r.t. the current LP solution and when cut filtering is performed; one can now fill the cut storage
5739 with cuts that were separated for different solutions
5740 - New separator for close cuts and a new function to compute relative interior points of the LP
5741 - added first version of sepa_closecuts.{c,h} to separate cuts w.r.t. a point that is closer to the integral polyhedron
5742
5743- Constraints:
5744 - implement possibility to force a restart in cons_indicator if enough indicator variables have been fixed
5745 - the xor constraint handler can now parse its constraints
5746 - the bounddisjunction constraint handler can now parse its constraints
5747 - the knapsack, setppc and soc constraint handler can now parse their constraints
5748 - the varbound constraint handler can now parse its constraints
5749 - added beta version of variable deletion: for branch-and-price application, variables can now be completely deleted
5750 from the problem; variables that are deletable have to be marked with SCIPvarMarkDeletable(), constraint handlers can
5751 implement the new `SCIP_DECL_DELVARS` callback that should remove variables from the constraints; at the moment, only
5752 the linear, the setppc and the knapsack constraint handler support this callback; furthermore, when using this
5753 feature, all used plugins have to capture and release variables they store in their data, this is currently only done
5754 for the aforementioned constraint handlers as well as the and, the varbound and the logicor constraint handler; for
5755 more details about this feature, see the FAQ
5756 - added pseudoboolean constraint handler (cons_pseudoboolean.{c,h})
5757 - added first version of cons_disjunction.{c,h} which allows a disjunction of constraints
5758 - added constraint handler for (absolute) power constraints (cons_abspower.{c,h}) to handle equations like z = sign(x)abs(x)^n, n > 1
5759
5760- Heuristics:
5761 - new heuristic vbounds which use the variables lower and upper bounds to fix variable and performs a neighborhood search
5762 - added vbound heuristic (heur_vbounds.{c,h})
5763 - added clique heuristic (heur_clique.{c,h})
5764
5765- Reading and Writing:
5766 - added writing for wbo files
5767 - added writing for pip files (linear, quadratic, polynomial nonlinear, polynomial abspower, polynomial bivariate, and
5768 and constraints)
5769 - CIP format variable characters defined, e.g. `SCIP_VARTYPE_INTEGER_CHAR`
5770 - Improved support for wbo format for weighted PBO problems, IBM's xml-solution
5771 format and pip and zimpl format for polynomial mixed-integer programs
5772 - New reader for (standard) bounds on variables
5773 - Extended reader for CIP models to handle various new constraints, including all types of linear constraints
5774 - flatzinc reader is now capable to read cumulative constraints
5775 - changed opb(/wbo) reader which now creates pseudoboolean constraints instead of linear- and and-constraints, only a
5776 non-linear objective will create and-constraints inside the reader and while reading a wbo file the topcost constraint
5777 is created as well
5778 - added clock for determine the time for reading
5779 - added reader for variable bounds (reader_bnd.{c,h})
5780 - Removed method SCIPreadSol(); call solution reading via SCIPreadProb() which calls the solution reader for .sol files.
5781
5782- Nonlinear:
5783 - Major extensions for nonlinear CIP, new option for n-ary branching on nonlinear variables (within pseudocost branching rule)
5784 - added BETA version of constraint handler for nonlinear constraints (cons_nonlinear.{c,h}) to handle nonlinear
5785 equations given by algebraic expressions using operands like addition, multiplication, power, exp, log, bivariate
5786 nonlinear constraints; currently no trigonometric functions
5787 - added BETA version of constraint handler for bivariate nonlinear constraints (cons_bivariate.{c,h}) to compute tight
5788 estimators for 1-convex and convex-concave bivariate nonlinear functions (given as expression tree)
5789 - the gams writer can now write nonlinear, abspower and bivariate constraints
5790 - Extended writer for GAMS and pip format to write more types of nonlinear constraints
5791 - the pip and zimpl reader now create nonlinear constraints for polynomials of degree > 2
5792
5793- Presolving:
5794 - new dual presolving methods in cons_setppc and cons_logicor
5795 - new presolving step `removeConstraintsDueToNegCliques` in locigor constraint handler which updates logicor constraints
5796 to setppc constraints if a negated clique inside this constraint exist, by default is off
5797 - new presolving step in cons_knapsack (detectRedundantVars, deleteRedundantVars) which determines redundant variables
5798 in knapsack constraint with or without using clique information
5799 - cons_logicor is now able to replace all aggregated variables in presolving by there active or negation of an active
5800 variable counterpart
5801 - prop_pseudoobj is now working in presolving as well
5802 - implement presolving in exitpre() in cons_orbitope and cons_indicator
5803
5804- Propagators:
5805 - added counter for number calls and timing for resolve propagation calls for constraint handler and propagators
5806 - Propagators are now also called in node presolving
5807 - the probing presolver presol_probing.{c.h} is now a propagator prop_probing.{c,h}, all corresponding parameters moved as well
5808 - the redcost separator sepa_redcost.{c.h} is now a propagator prop_redcost.{c,h}, all corresponding parameters moved as well
5809 - outsourced propAndSolve() method in solve.c which calls domain propagation and solving of the lp and relaxation
5810
5811- Statistic:
5812 - solutions which are given by the user from the outside are now marked by `#` in the output
5813 - the `Solving Time` is now spitted into presolving, solving and reading time
5814 - Presolvers section has new column `AddCons` which states the number of added constraint
5815 - Constraints section has new column named \#ResProp which show the number of resolve propagation calls of certain
5816 constraint handler
5817 - Constraint Timing section has a new column \#ResProp which states the time spend in resolve propagation method of the
5818 constraint handler
5819 - improved output of propagators in display statistics
5820 - new section `Propagator Timing` which shows the time spend in different callbacks of the propagator
5821 - rearranged first two columns of Propagators section; \#Propagate and \#ResProp stating the number of call for
5822 propagation and resolve propagation; the Time column is moved into the new section Propagator Timings
5823 - Constraints section has new column named `MaxNumber` which the maximum number of active constraint of a certain
5824 constraint handler
5825 - added two columns `Time-0-It` and `Calls-0-It` in the LP section which states the number of LP call and time spend for
5826 solving LPs with zero iterations (only refactorization)
5827 - The display of statistics for presolvers, propagators, constraints and LP solving has changed.
5828
5829Performance improvements
5830------------------------
5831
5832- Reorganized filtering process of separation storage (allows adding cuts for different solutions)
5833- Improved presolving for various constraint handlers
5834- Improved propagation methods for variable bound constraints
5835- Improved performance for quadratic constraints
5836- performance improvements in prop_vbounds
5837- child selection rules now get also applied when the relaxation value is equal to the bound changed in branching
5838- added dual reduction to cons_cumulative.c
5839- for continuous variables, the pseudo costs update and the pscost branching rule now use the same strategies for
5840 updating the pseudo costs and estimating the improvement in the LP bound
5841- only perform probing if the variables are locked
5842- performance and memory consumption improvements in xmlparse.c
5843- Improved knapsack cover cuts
5844- avoid very long separation times of LEWIs in cons_knapsack for very large minimal covers
5845- used SCIPallocMemoryArray() instead of SCIPallocBlockMemoryArray() which leads to fewer memory consumption in
5846 getLiftingSequence() in cons_knapsack, also improved cache use bei using an extra array instead blockmemory chunks
5847- switched FASTMIP from 1 to 2 for CPLEX and changed default pricing rule back to steepest edge pricing instead of
5848 quickstart steepest edge pricing
5849- made sorting method more robust
5850- LNS heuristics now use SCIPcopy() by default
5851- considering inactive variables in undercover heuristic; limiting effort for solving covering problem
5852- if during probing mode the LP relaxation is solved from scratch, e.g., when calling the shiftandpropagate heuristic
5853 before root node solving, then we clear the resulting LP state, since it might be a bad starting basis for the next
5854 solve of the LP relaxation (controlled by new parameter `lp/clearinitialprobinglp`)
5855- included LP simplifier into SoPlex LP interface, applied when solving from scratch (lpi_spx.cpp)
5856- new presolving steps in varbound constraint handler, tightening bounds, coefficients, sides and pairwise presolving
5857
5858Interface changes
5859-----------------
5860
5861- Miscellaneous:
5862 - The emphasis setting types now distinguish between plugin-type specific parameter settings (default, aggressive, fast, off),
5863 which are changed by SCIPsetHeuristics/Presolving/Separating(), and global emphasis settings (default, cpsolver, easycip,
5864 feasibility, hardlp, optimality, counter), which can be set using SCIPsetEmphasis().
5865
5866### New and changed callbacks
5867
5868- added propagator timings `SCIP_PROPTIMING_BEFORELP`, `SCIP_PROPTIMING_DURINGLPLOOP` and `SCIP_PROPTIMING_AFTERLPLOOP` for
5869 all propagation callbacks (see propagators and constraint handlers) which lead to calling the propagation methods of a
5870 propagator before the lp is solved, during the lp loop and after the lp solving loop
5871
5872- Conflict Analysis:
5873 - Added parameter `separate` to conflict handler callback method SCIP_DECL_CONFLICTEXEC() that defines whether the conflict
5874 constraint should be separated or not.
5875
5876- Constraint Handler:
5877 - The new constraint handler callback SCIP_DECL_CONSDELVARS() is called after variables were marked for deletion.
5878 This method is optional and only of interest if you are using SCIP as a branch-and-price framework. That means,
5879 you are generating new variables during the search. If you are not doing that just define the function pointer
5880 to be `NULL`.
5881 If this method gets implemented you should iterate over all constraints of the constraint handler and delete all
5882 variables that were marked for deletion by SCIPdelVar().
5883
5884- NLP Solver Interface:
5885 - The callbacks SCIP_DECL_NLPIGETSOLUTION() and SCIP_DECL_NLPISETINITIALGUESS() got new parameters to get/set values of
5886 dual variables.
5887 - The callback SCIP_DECL_NLPICOPY() now passes the block memory of the target SCIP as an additional parameter.
5888
5889- Presolving:
5890 - New parameters `isunbounded` and `isinfeasible` for presolving initialization (SCIP_DECL_CONSINITPRE(),
5891 SCIP_DECL_PRESOLINITPRE(), SCIP_DECL_PROPINITPRE()) and presolving deinitialization (SCIP_DECL_CONSEXITPRE(),
5892 SCIP_DECL_PRESOLEXITPRE(), SCIP_DECL_PROPEXITPRE()) callbacks of presolvers,
5893 constraint handlers and propagators, telling the callback whether the problem was already declared to be
5894 unbounded or infeasible. This allows to avoid expensive steps in these methods in case the problem is already
5895 solved, anyway.
5896
5897 Note, that the C++ methods
5898 - scip::ObjConshdlr::scip_presol() corresponding to SCIP_DECL_CONSPRESOL()
5899 - scip::ObjConshdlr::scip_initpre() corresponding to SCIP_DECL_CONSINITPRE()
5900 - scip::ObjPresol::scip_initpre() corresponding to SCIP_DECL_PRESOLINITPRE()
5901 - scip::ObjProp::scip_initpre() corresponding to SCIP_DECL_PROPINITPRE()
5902 - scip::ObjConshdlr::scip_exitpre() corresponding to SCIP_DECL_CONSEXITPRE()
5903 - scip::ObjPresol::scip_exitpre() corresponding to SCIP_DECL_PRESOLEXITPRE()
5904 - scip::ObjProp::scip_exitpre() corresponding to and SCIP_DECL_PROPEXITPRE()
5905 are virtual functions. That means, if you are not adding the new parameters, your code will still compile, but these methods are not executed.
5906 - Propagators are now also called in during presolving, this is supported by the new callback methods SCIP_DECL_PROPINITPRE(),
5907 SCIP_DECL_PROPEXITPRE(), and SCIP_DECL_PROPPRESOL().
5908 - The new parameters `nnewaddconss` and `naddconss` were added to the constraint handler callback method SCIP_DECL_CONSPRESOL()
5909 and the presolver callback method SCIP_DECL_PRESOLEXEC(). These parameters were also added to corresponding C++ wrapper
5910 class methods (scip_presol() in objconshdlr.h and scip_exec() in objpresol.h)
5911
5912- Problem Data:
5913 - The callback SCIP_DECL_PROBCOPY() got a new parameter `global` to indicate whether the global problem or a local version is copied.
5914
5915### Deleted and changed API methods
5916
5917- implemented SCIPlpiGetPrimalRay() in SoPlex interface that has become available with SoPlex version 1.5.0.2
5918- allowed calling SCIPgetRowSolActivity() in `SCIP_STAGE_SOLVED`, since LP is still available
5919- various extensions and modifications for expressions and expression trees (too much to state here)
5920- The result value `SCIP_NEWROUND` has been added, it allows a separator/constraint handler to start a new separation round
5921 (without previous calls to other separators/conshdlrs).
5922- SCIPcalcNodeselPriority() got a new parameter `branchdir`, which defines the type of branching that was performed: upwards, downwards, or fixed.
5923
5924- Constraint Handlers:
5925 - Method SCIPincludeQuadconsUpgrade() of quadratic constraint handler got new parameter `active` to indicate whether the upgrading method is active by default.
5926 - Method SCIPseparateRelaxedKnapsack() in knapsack constraint handler got new parameter `cutoff`, which is a pointer to store whether a cutoff was found.
5927
5928- Nonlinear expressions, relaxation, and solver interface:
5929 - SCIPcreateNLPSol() now creates a `SCIP_SOL` that is linked to the solution of the current NLP relaxation
5930 - Various types and functions dealing with polynomial expressions have been renamed to use the proper terms `monomial` and
5931 `polynomial` in nonlinear expressions (nlpi/∗expr*); results in many renamings of types, structs and methods.
5932 - The methods SCIPnlpGetObjective(), SCIPnlpGetSolVals(), and SCIPnlpGetVarSolVal() have been removed, use SCIPgetNLPObjval(),
5933 SCIPvarGetNLPSol() and SCIPcreateNLPSol() to retrieve NLP solution values instead.
5934 SCIPcreateNLPSol() now returns an error if NLP or NLP solution is not available
5935 - Removed methods SCIPmarkRequireNLP() and SCIPisNLPRequired(), because the NLP is now always constructed if nonlinearities
5936 are present.
5937 - SCIPgetNLP() has been removed and NLP-methods from pub_nlp.h have been moved to scip.h, which resulted in some renamings, too.
5938 - renamed SCIPexprtreeEvalSol() to SCIPevalExprtreeSol() and now located in scip.h.
5939 - renamed SCIPexprtreeEvalIntLocalBounds() to SCIPevalExprtreeLocalBounds() and now located in scip.h.
5940 - renamed SCIPexprtreeEvalIntGlobalBounds() to SCIPevalExprtreeGlobalBounds() and now located in scip.h.
5941 - The functions SCIPnlpiGetSolution() and SCIPnlpiSetInitialGuess() got additional arguments to get/set dual values.
5942 - The method SCIPgetNLPI() got a new parameter `nlpiproblem`, which is a pointer to store the NLP solver interface problem.
5943
5944- Timing:
5945 - SCIPincludeProp() got additional parameters to set the timing mask of the propagator and the new callbacks and parameters
5946 related to calling the propagator in presolving.
5947 - SCIPincludeConshdlr() got additional parameters to set the variable deletion callback function and the timing mask for
5948 propagation.
5949 - removed parameters timelimit and memorylimit from SCIPapplyRens()
5950 - The parameters `timelimit` and `memorylimit` were removed from SCIPapplyRens().
5951
5952- Problem Data:
5953 - The method SCIPcopyProb() got a new parameter `global` to indicate whether the global problem or a local version is copied.
5954
5955- Writing and Parsing Constraints:
5956 - The methods SCIPwriteVarName(), SCIPwriteVarsList(), and SCIPwriteVarsLinearsum() got a new boolean parameter `type`
5957 that indicates whether the variable type should be written or not.
5958 - The methods SCIPparseVarName() and SCIPparseVarsList() got a new output parameter `endptr` that is filled with the position
5959 where the parsing stopped.
5960 - The method SCIPwriteVarsList() got additionally a new parameter `delimiter` that defines the character which is used for delimitation.
5961
5962- Variables:
5963 - SCIPmarkDoNotMultaggrVar()/SCIPvarMarkDoNotMultaggr() now allow to mark negated and aggregated variables
5964 - SCIPgetVarCopy() got a new parameter `success` that will be FALSE if method is called after problem creation stage and no hash map is
5965 given or no image for the given variable is contained in the given hash map.
5966 - SCIPchgVarType() got an extra boolean parameter to store if infeasibility is recognized while upgrading a variable from continuous
5967 type to an integer type.
5968 - SCIPdelVar() got a new parameter `deleted`, which stores whether the variable was successfully marked to be deleted.
5969
5970### New API functions
5971
5972- information about the quality of the solution of an LP (currently the condition number of the basis matrix) can now be:
5973 + requested from the LPI (currently only available for CPLEX): methods SCIPlpiGetRealSolQuality() and
5974 + SCIPprintLPSolutionQuality() command display lpsolquality in interactive shell display column lpcond to show
5975 + estimate on condition number, if available
5976- SCIPround() and SCIPfeasRound() to round to nearest integer
5977- SCIPsortRealRealIntInt() and corresponding sorting/inserting/deleting methods in pub_misc.h and necessary defines in misc.c
5978- SCIPsortRealIntLong(), SCIPsortPtrPtrRealInt() and corresponding sorting/inserting/deleting methods in
5979 pub_misc.h and necessary defines in misc.c
5980- SCIPcomputeLPRelIntPoint() to compute relative interior point of the current LP
5981- SCIPstartSolvingTime() and SCIPstopSolvingTime() which can be used to start or stop the solving time clock
5982- SCIPstrToRealValue() and SCIPstrCopySection() in pub_misc.h; these methods can be used to convert a string
5983 into a `SCIP_Real` value and to copy a substring.
5984- SCIPgetBinvarRepresentatives() which gets binary variables that are equal to some given binary variables,
5985 and which are either active, fixed, or multi-aggregated, or the negated variables of active, fixed, or multi-aggregated variables
5986- SCIPhasPrimalRay() and SCIPgetPrimalRayVal() that return whether a primal ray is stored and which value a
5987 given variable has in the primal ray, respectively
5988- SCIPsetConsModifiable()
5989- SCIPsetParam() which is a generic parameter setter method, independent of the parameter type
5990- SCIPpropInitpre(), SCIPpropExitpre(), SCIPpropPresol() which initializes, exists and executes the presolving phase
5991- SCIProwGetAge() to access the age of a row (pub_lp.h/lp.c)
5992- SCIPsolGetOrigObj() in pub_sol.h which returns for a solution in the original problem space the objective value
5993- SCIPretransformSol() in scip.h that allows to retransform a solution to the original space
5994- SCIPlpiClearState() to LP interfaces for clearing basis information in the LP solver
5995- SCIPgetSubscipDepth() to access the depth of the current SCIP as a copied subproblem
5996- SCIPdebugAddSolVal() and SCIPdebugGetSolVal() to add/get values to/from a debug solution
5997- SCIPsepastoreRemoveInefficaciousCuts() to remove non-efficious cuts from the separation storage
5998
5999- Nodes:
6000 - SCIPnodeGetParent() to get parent node of a node
6001 - SCIPnodesSharePath() in pub_tree.h that determines whether two nodes are on the same leaf-root path
6002 - SCIPnodesGetCommonAncestor() in pub_tree.h that finds the common ancestor node for two given nodes
6003
6004- Read and Write:
6005 - SCIPgetReadingTime() which returns the time for reading in seconds
6006 - SCIPparseVarsLinearsum(), SCIPparseVarsPolynomial() and SCIPwriteVarsPolynomial() and for writing and
6007 parsing polynomials in constraint handler writing/parsing methods
6008
6009- Memory:
6010 - SCIPcreateMesshdlrPThreads() and SCIPfreeMesshdlrPThreads() for allocating and deleting necessary memory
6011 for message handlers for parallel pthread version
6012 - SCIPallocClearMemoryArray() and BMSallocClearMemoryArray() for allocating cleared memory arrays in scip.h and memory.h
6013
6014- Intervals:
6015 - SCIPintervalPowerScalarInverse() to solve an equation y = x^p for given bounds on y and scalar exponent p
6016 - SCIPintervalQuadBivar() to compute tight bounds on a bivariate quadratic form
6017 - SCIPintervalSolveBivariateQuadExpressionAllScalar() to compute tight bounds on the solutions of a bivariate quadratic equation
6018
6019- Variables:
6020 - SCIPcomputeVarCurrent{L,U}b{Local,Global}() to compute local or global lower or upper bounds of a
6021 multiaggregated variable from the bounds of the aggregation variables
6022 - SCIPbranchVarValNary() for n-ary variable branching
6023 - SCIPgetNegatedVars() which returns all negated variables for a given array of variables, if the negated
6024 variables are not existing yet, they will be created
6025 - SCIPgetNTotalVars() that returns the total number of created vars, icluding variables that were deleted in the meantime
6026 - SCIPvarGetHashkey(), SCIPvarIsHashkeyEq(), SCIPvarGetHashkeyVal() in pub_var.h which can be used for `SCIP_HASHTABLE` of variables
6027 - SCIPvarGetNBdchgInfosLb() and SCIPvarGetNBdchgInfosUb() in pub_var.h returning the number of lower or upper bound changes on the active path
6028 - SCIPvarGetBdchgInfoLb() and SCIPvarGetBdchgInfoUb() returning the bound change information at the given position
6029 - SCIPvarMarkDeletable() to mark a variable to be deletable completely from the problem (for
6030 branch-and-price); can only be called before the variable is added to the problem
6031 - SCIPvarMarkNotDeletable() that marks a variable to be non-deleteable (used within SCIP for forbidding
6032 deletion of variables contained in solution, LP bases, (multi)aggregation, ...)
6033 - SCIPvarIsDeletable() that returns whether a variable is marked to be deletable (each variable is per default non-deletable)
6034
6035- NLP:
6036 - SCIPgetNLPVarsNonlinearity() to get for each variable in the NLP the number of NLP rows in which this variable appears in a nonlinear way
6037 - SCIPnlrowGetDualsol(), SCIPgetNLPVarsLbDualsol(), SCIPgetNLPVarsUbDualsol() to retrieve dual values from an NLP solution
6038 - SCIPgetNLPFracVars() to get the fractional variables in an NLP solution
6039
6040- Propagator:
6041 - SCIPpropSetPresolPriority() which changes the presolving priority of a given propagator
6042 - SCIPpropGetPresolPriority(), SCIPpropGetPresolTime(), SCIPpropWasPresolDelayed(), SCIPpropGetNFixedVars(),
6043 SCIPpropGetNAggrVars(), SCIPpropGetNChgVarTypes(), SCIPpropGetNChgBds(), SCIPpropGetNAddHoles(), SCIPpropGetNDelConss(),
6044 SCIPpropGetNAddConss(), SCIPpropGetNUpgdConss(), SCIPpropGetNChgCoefs(), SCIPpropGetNChgSides(), SCIPpropGetTimingmask(),
6045 SCIPpropDoesPresolve() which return corresponding presolving information
6046 - SCIPpropGetNRespropCalls() and SCIPconshdlrGetNRespropCalls() which return the number of times a
6047 propagator or a constraint handler was called for resolving a propagation
6048 - SCIPpropGetRespropTime() and SCIPconshdlrGetRespropTime() which return time spent for resolving a
6049 propagation within a propagator or a constraint handler
6050 - SCIPcheckCumulativeCondition(), SCIPpropCumulativeCondition() and SCIPrespropCumulativeCondition() in
6051 cons_cumulative.h; these methods can be used to check, propagate, or resolve the propagation of a cumulative condition
6052 - SCIPpropagateCutoffboundVar() in prop_pseudoobj.h which can be used to propagate the cutoff bound for the given variables
6053
6054- Constraints:
6055 - added to linear constraint handler SCIPsetUpgradeConsLinear(), which (de-)activates the possibility to
6056 upgrade a linear constraint to a specialized linear constraint (e.g. knapsack)
6057 - SCIPconvertCutsToConss() and SCIPcopyCuts() to scip.{c,h} for copying cuts to linear constraints
6058 - SCIPaddCoefLogicor() to add a variable to a logic or constraint
6059 - SCIPfindOrigCons() which return a original constraint with the given name or `NULL`
6060 - SCIPconshdlrGetNAddConss() which returns the number of added constraints during presolving by a given constraint handler
6061 - SCIPpresolGetNAddConss() which returns the number of added constraints during presolving by a given presolver
6062
6063### Command line interface
6064
6065- New funtionalities in the interactive shell (modify current CIP instance, write NLP relaxation)
6066- added dialog `write nlp` to write current NLP relaxation to a file
6067- new dialog `change freetransproblem` to free transformed problem in the interactive shell before changing the problem
6068- it is possible to change bounds of a variable in the interactive shell
6069- it is possible to add a constraint to a problem in the interactive shell
6070
6071### Interfaces to external software
6072
6073- Improved SOPLEX interface (LP simplifier)
6074- Improved CPLEX interface, including measures for numerical stability
6075
6076### Changed parameters
6077
6078- change default value of parameter `nodeselection/restartdfs/selectbestfreq` 100
6079- moved parameters for pseudoboolean constraints from opb-reader to pseudoboolean constraint handler
6080- changed possible parameter values of `branching/pscost/strategy` from `bri` to `cdsu`: default is now `u`, i.e., to
6081 estimate the LP gain by a branching for external branching candidates (esp. continuous variables) the same way as
6082 their pseudo costs are updated
6083- added possible value `d` for `constraints/soc/nlpform` to choose a convex division form for SOC constraint
6084 representation in NLP
6085- renamed parameter `constraints/quadratic/linearizenlpsol` to `constraints/quadratic/linearizeheursol` and do
6086 linearizations in every solution found by some heuristic
6087- renamed parameter `constraints/quadratic/mincutefficacyenfo` to `constraints/quadratic/mincutefficacyenfofac` and
6088 interpret it as a factor of the feasibility tolerance
6089- removed fastmip setting 2, which means the dualsolution would not be calculated but because SCIP always asks for the
6090 dual solution, the lp would be reoptimized to calculate them; so it had no real effect
6091- all parameters in cons_indicator and cons_sos1 have been converted to lower case!
6092- changed default value of parameter `separating/gomory/maxroundsroot` to 10
6093- changed default value of parameter `separating/gomory/maxsepacutsroot` to 50
6094- removed parameter `heuristics/subnlp/nlpsolver`, use `nlp/solver` instead
6095
6096### New parameters
6097
6098- `branching/delaypscostupdate` to delay the update of pseudo costs for continuous variables behind the separation round: default is TRUE
6099- `branching/lpgainnormalize` to set the strategy how the LP gain for a continuous variable is normalized when updating the
6100 variables pseudocosts: default is to divide LP gain by reduction of variable's domain in sibling node
6101- `branching/pscost/nchildren` and `branching/pscost/nary*` to enable and customize n-ary branching on
6102 external branching candidates (e.g., in spatial branching for MINLP)
6103- `conflict/bounddisjunction/continuousfrac` which defines the maximum percantage of continuous variables
6104 within a conflict create by the bounddisjunction conflict handler
6105- `conflict/separate` which enables or disables the separation of conflict constraints
6106- `constraints/{nonlinear,quadratic,soc,abspower}/sepanlpmincont` to specify minimal required fraction
6107 of continuous variables in problem to enable linearization of convex constraints in NLP relaxation solution in root
6108- `constraints/indicator/forcerestart` and `constraints/indicator/restartfrac` to control forced restart in cons_indicator
6109- `constraints/indicator/generatebilinear` to generate bilinear (quadratic) constraints instead of indicator constraints
6110- `constraints/indicator/maxconditionaltlp` to enable a quality check for the solution of the alternative LP
6111- `constraints/indicator/removeindicators` to remove indicator constraints if corresponding vub has been added
6112- `constraints/linear/nmincomparisons` and `constraints/linear/mingainpernmincomparisons` to influence
6113 stopping criterium for pairwise comparison of linear constraints
6114- `constraints/pseudoboolean/decompose`, for pseudoboolean constraints to transform pseudoboolean constraints into linear- and and-constraints
6115- `constraints/quadratic/binreforminitial` to indicate whether linear (non-varbound) constraints added due to reformulation of products with
6116 binary variables in a quadratic constraints should be initial (if the quadratic constraint is initial), default is FALSE
6117- `constraints/quadratic/checkfactorable` to disable check for factorable quadratic functions (xAx = (ax+b)*(cx+d)) in quadratic constraints
6118 and not to use of this information in separation (generates lifted tangent inequalities according to Belotti/Miller/Namazifar if also
6119 linear vars are present)
6120- `constraints/quadratic/disaggregate` to split a block-separable quadratic constraint into several quadratic constraint
6121- `constraints/quadratic/maxproprounds` and `constraints/quadratic/maxproproundspresolve` to limit the
6122 number of propagations rounds for quadratic constraints within one propagation round of SCIP solve or during SCIP presolve
6123- `constraints/varbound/presolpairwise` that allows pairwise presolving of varbound constraints, default is TRUE
6124- `heuristics/shiftandpropagate/onlywithoutsol` to switch whether the heuristic should be called in case a primal solution is already present
6125- `limit/maxorigsol` which defines the size of the solution candidate store (default value is 10)
6126- `lp/resolverestore` controlling how LP solution is restored after diving: if TRUE by resolving them,
6127 if FALSE by buffering them; if `lp/freesolvalbuffers` is TRUE, we free the buffer memory each time (FALSE by default)
6128- `lp/clearinitialprobinglp` to clear LP state at end of probing mode, if LP was initially unsolved
6129- `lp/resolveitermin` and `lp/resolveiterfac` to limit the number of LP iterations in resolving calls:
6130 resolveiterfac is a factor by which the average number of iterations per call is multiplied to get the limit, but the
6131 limit is at least resolveitermin; default is -1 (no limit) for resolveiterfac and 1000 for resolveitermin
6132- `lp/resolverestore` and `lp/freesolvalbuffers` possibility to buffer and restore LP solution after diving without
6133 having to resolve the LP; currently turned off, because performance impact is unclear;
6134- `misc/improvingsols` which states whether only solutions which have a better (or equal) primal bound
6135 as the best known are checked; this is of interest if the check of a solution is expensive; default value is FALSE
6136- `misc/resetstat` which state if the statistics should be reseted if the transformed problem is freed
6137 (in case of a benders decomposition this parameter should be set to FALSE) default value is TRUE
6138- `nodeselection/restartdfs/countonlyleafs` in node selector restart dfs which can be used to select the counting process of processed nodes
6139- `presolving/donotaggr` to deactivate aggregation of variables globally
6140- `pricing/delvars` and `pricing/delvarsroot` that define, whether variables created at a node / the
6141 root node should be deleted when the node is solved in case they are not present in the LP anymore
6142- `propagating/%s/maxprerounds` for all propagators which allows to change to maximal number of rounds
6143 of presolving where this propagator participates in
6144- `propagating/%s/presoldelay` for all propagators which allows to change if the presolving call of the given propagator should be delayed
6145- `propagating/%s/presolpriority` for all propagators which allows to change the priority of calling the given propagator
6146- `propagating/pseudoobj/propfullinroot` for allowing to propagate all variables in the root node,
6147 instead of stopping after `maxcands` which is set by a parameter as well
6148- `reading/gmsreader/bigmdefault` and `reading/gmsreader/indicatorreform` reader_gms is now able to write indicator
6149 constraints (reformulated either via big-M or sos1)
6150- `reading/gmsreader/signpower` to enable writing sign(x)abs(x)^n as the rarely used gams function signpower(x,n)
6151- `separating/closecuts/maxunsucessful` to turn off separation if we can not find cuts
6152- `timing/reading` to add reading time to solving time
6153
6154### Data structures
6155
6156- split off `PARAMEMPHASIS` from `PARAMSETTING` (in pub_paramset.c/paramset.c)
6157- new data structure `SCIP_STAIRMAP`
6158- add expression graph data structures and methods for reformulation, domain propagation, simple convexity check on
6159 nonlinear expressions and simplification for expression trees and graphs
6160
6161Testing
6162-------
6163
6164- New scripts for running tests with GAMS
6165- added scripts check_gams.sh, evalcheck_gams.sh and check_gams.awk and target `testgams` in Makefile
6166- adjusted all test scripts to use the same new optimality gap computation as in SCIP
6167- added Makefile option `VALGRIND=true` to enable running the SCIP checks (make test) through valgrind; valgrind errors
6168 and memory leaks are reported as fails
6169- moved *.test and *.solu files to subdirectory testset in check directory and adjusted test scripts
6170
6171Build system
6172------------
6173
6174### Makefile
6175
6176- Variables:
6177 - via `PARASCIP=true` as a `Makefile` option it is possible to compile SCIP threadsafe in DEBUG-mode, (in OPT-mode it's
6178 only necessary if non-default messagehandler or CppAD is used)
6179 - the `make` parameter `PARASCIP=true` leads to threadsafe message handlers where you need to call
6180 SCIPcreateMesshdlrPThreads() and SCIPmessageSetHandler()/SCIPmessageSetDefaultHandler() and SCIPfreeMesshdlrPThreads();
6181 therefore we need to link with pthread library
6182 - new variable $(INSTALLDIR) in Makefile which define installation directory for the libraries, $(INSTALLDIR)/lib/,
6183 binary, $(INSTALLDIR)/bin and include headers, $(INSTALLDIR)/include, the default value is the empty string
6184
6185- Linking:
6186 - Linking against Clp and Ipopt has been simplified. Only the directory where the
6187 package has been installed need to be provided now. For details see the INSTALL file.
6188 - to link against IPOPT, only the base directory of an Ipopt installation need to be specified now; additionally, if
6189 building with gnu compilers, the Ipopt libraries directory is stored in the SCIP binary, which should make it easier
6190 to run with Ipopt shared libraries
6191 - to link against Clp, only the base directory of an Clp installation needs to be specified now
6192
6193- Targets:
6194 - New targets `(un)install` in Makefile, support for valgrind in testing environment
6195 - new target `make libs` which compiles only the libraries
6196 - new target in Makefile `install` performs `make` and copies using the install command the include headers, binary, and
6197 libraries
6198 - new target in Makefile `uninstall` removes libraries, binary and include headers form `INSTALLDIR`
6199 - removed target `lintfiles`, this target is now imitated by the `lint` target and a none empty variable `FILES`
6200
6201Fixed bugs
6202----------
6203
6204- fixed bug in copying if the target SCIP already is in solving stage: it might be that the copy of a variable cannot be found/created
6205- fixed bug trying to print big messages bigger than `SCIP_MAXSTRLEN`
6206- fixed bug w.r.t. counting feasible solutions and turned of sparse solution test
6207- LP solution status is now checked when checking root LP solution. Otherwise, due to different time measurements, it
6208 might happen that the LP solving was stopped due to the time limit, but SCIP did not reach the limit, yet.
6209- fixed bug trying to tighten multiaggregated variables, which have only one active representation and this variable is already tightened
6210- fixed possible buffer overrun in tclique_graph.c
6211- fixed issue with interactive shell in case (user) plugins are included after the default plugins
6212- fixed bug where mutiaggregating leads to an aggregation and both variables were of implicit or integral type
6213- fixed bug in conflict.c, where LPi was manipulated, but not marked as not solved
6214
6215- Tree:
6216 - fixed assertion in tree.c w.r.t. node estimation
6217 - fixed bug in debug.c: removed tree nodes had not been checked if they were pruned due to an incumbent solution found by a diving heuristic
6218
6219- Bounds:
6220 - fixed bug which occured when changing a bound in the solving stage when this variables got upgraded from continuous to
6221 a integer type, where the bounds of this variable were still not integral; due to that SCIPchgVarType() has changed (see above)
6222 - fixed bug in handling of lazy bounds that resulted in putting the bounds explicitly into the LP
6223
6224- Separation:
6225 - fixed assert in sepa_clique.c which is currently not valid because implicit binary variables in cliques are ignored
6226 - fixed bug in sepa_zerohalf.c concerning inconsistent construction of solution array of variables and fixed wrong assert about variable bounds
6227
6228- Constraints:
6229 - fixed not correct merging of variable in logicor constraint handler and changed the name of the method to a common
6230 name used by other constraint handlers too(findPairsAndSets->mergeMultiples)
6231 - fixed bugs in changing the initial and checked flags for constraints in original problem
6232 - fixed bug in cons_linear.c, when scaling a constraint maxabscoef was not set correctly, furthermore the correction of
6233 maxabscoef was not handled correctly
6234 - fixed bug in cons_indicator.c trying to copy a constraint where the pointer to the linear constraint did not point to
6235 the already transformed linear constraint (, happend when SCIPcopy() is used after transforming before presolving)
6236 - fixed numerical bug in linear constraint handler: polishing of coefficients after fixing variables led to wrong
6237 results for continuous variables fixed to a close-to-zero value.
6238 - fixed bug in cons_bounddisjunction where branching on multiaggregated variables was tried while all aggregation variables are fixed
6239 - fixed bug in presolving of cons_logicor.c: adding variable implications can lead to further reductions; added call to applyFixings()
6240 - fixed bug in cons_countsols.c w.r.t. none active variables
6241 - fixed bug in cons_linear.c, scaling could have led to wrong values
6242
6243- Reader:
6244 - fixed bug in reader_fzn.c w.r.t. cumulative constraints
6245 - fixed bug in reader_mps.c: if a variables first occurence is in the bounds section, then the corresponding variable bound was lost
6246 - fixed several issues in flatzinc reader
6247 - deactived checking of zero solution in Zimpl reader when no starting values are provided
6248 - reader_lp is now able to read lines longer than 65534 characters
6249
6250- Memory:
6251 - fixed bug in copying NLPI interfaces that use block-memory (NLPI copy used block memory from source SCIP)
6252 - fixed memory leak in reader_pip.c
6253 - fixed memory leak in coloring part of maximum clique algorithm (tclique_coloring.c)
6254 - fixed memory leak in coloring part of maximum clique algorithm (tclique_coloring.c) in a better way
6255
6256- Numerics:
6257 - fixed bug which occured when the dual farkas multipliers were not available in the lpi because the LP could only be
6258 solved with the primal simplex due to numerical problems
6259 - fixed bug in ZI round heuristic that led to infeasible shiftings for numerically slightly infeasible rows with close-to-zero coefficients
6260 - fixed numerical issue in octane heuristic: close-to-zero values for ray direction could have led to bad computations
6261
6262- Propagation:
6263 - fixed bug in propagation of indicator constraints: cannot fix slack variable to 0 if linear constraint is disabled/not active
6264 - fixed bug in cons_linear.c while sorting the eventdatas during the binary variable sorting for propagation
6265 - fixed bug and wrong assert in heur_shiftandpropagate.c when relaxing continuous variables from the problem
6266 - fixed bug in cons_orbitope:resprop() for the packing case
6267 - fixed wrong changing of wasdelayed flag for propagators
6268 - fixed bug using wrong sign in infinity check in prop_pseudoobj
6269 - fixed bug in redcost propagator: can only be called if the current node has an LP
6270 - fixed bug w.r.t. infinity loop during propagation
6271
6272Miscellaneous
6273-------------
6274
6275- The interface contains several additional callback functions and parameters for plugins. Some effort may be required to compile your old
6276 projects with SCIP 2.1. For details see section `Changes between version 2.0 and 2.1` in the doxygen documentation.
6277
6278@page RN20 Release notes for SCIP 2.0
6279
6280@section RN202 SCIP 2.0.2
6281*************************
6282
6283Performance improvements
6284------------------------
6285
6286- improved twoopt-heuristic by considering larger search domains
6287- the SoPlex interface now has the capability to provide a primal ray, provided it is compiled against the next SoPlex release (>= 1.5.0.2)
6288- calculation of node priority now also works when variable's relaxation value is equal to a bound
6289- fixed issue w.r.t. calling primal heuristics after presolving detected infeasibility
6290
6291- Constraints:
6292 - fasten propagation in cons_knapsack.c due to negated clique partitions
6293 - recalculating only needed partitions in cons_knapsack.c, not always both
6294
6295- Memory:
6296 - reduced memory usage of shift-and-propagate heuristic
6297 - knapsack constraints are now separated faster; SCIPsolveKnapsackExactly() now works faster and requires less memory
6298 - fasten knapsack separation by replacing SCIPallocBuffer(Array) through SCIPallocBlockMemory(Array)
6299 - improved runtime and memory consumption in SCIPsolveKnapsackExactly() in cons_knapsack.c
6300
6301Fixed bugs:
6302----------
6303
6304- fixed `make/make.project`
6305- fixed wrong assert in plugins that use SCIPcopy()
6306- fixed bug in DINS w.r.t. column generation
6307- fixed bug in var.c where a possible multiaggregation was resolved to an aggregation but the variables types were not
6308 checked to prefer more general types for aggregating; possible memory loss removed
6309- fixed bug in prop_vbounds.c w.r.t. infinity lower and upper bound of variable bound variables
6310- fixed bug w.r.t. setting wall clocks
6311- fixed wrong assert in var.c (replaced `==` through SCIPsetIsEQ()), real values do not have to be exactly the same when
6312 computed in different function
6313- fixed bug in SCIPsolveIsStopped() where it could happen that TRUE was reported if a nodelimit was reached but
6314 checknodelimits had been set to FALSE
6315- fixed three bugs when writing in fzn format (wrongly splitted writing buffer, wrong variables was used, floats were printed to short)
6316- fixed bug in conflict.c, infeasibility analysis with big values led to wrong result
6317
6318- Heuristics:
6319 - fixed bug in DINS heuristic that occured when the incumbent solution value is outside the variable's current domain
6320 - fixed behavior of LNS heuristics when the subproblem aborts: continue in optimized mode, stop in debug mode
6321 - fixed segmentation fault in heur_subnlp.c which occured if resolving the NLP with a tighter feasibility tolerance
6322 failed with a solver error
6323 - fixed bug in heur_subnlp.c where constraints forbidding variable fixations where added if a cutoff was used in the subproblem
6324 - fixed bug in heur_subnlp.c where wrong constraints forbidding variable fixations where added in case of general integers
6325
6326- NLP:
6327 - fixed bug in changing quadratic coefficients of a row in the NLP
6328 - fixed various small bugs in nonlinear expressions code
6329 - fixed removal of fixed linear variables from a nonlinear row: a fixed variable may have not been removed if there was
6330 also a multiaggregated variable
6331
6332- LP:
6333 - implemented SCIPlpiGetPrimalRay() in SoPlex interface that has become available with SoPlex version 1.5.0.2
6334 - fixed two bugs at nodes with unbounded LP relaxation: don't check lp rows of infinite solution; don't analyze conflict
6335 due to primal cutoff bound of -infinity
6336 - fixed wrong assumption that an optimal LP solution in the root is optimal for the problem if there are no active
6337 pricers, need to check also whether all variables are in the LP
6338
6339- Constraints:
6340 - fixed bug in reader_cip regarding reading of very long constraints
6341 - fixed bug while after restarting possible the aggregted variables were not removed in setppc constraints
6342 - fixed bug in cons_knapsack: in seldom circumstances the relaxation of a linear constraint can detect infeasibility,
6343 which was not handled properly
6344 - fixed bug w.r.t. to pricing variables in case new initial constraints come in during the price and cut loop
6345 - fixed bug in cons_soc.c w.r.t. upgrading from quadratic constraints with finite left-hand-side
6346 - fixed bug caused by not (correctly) counting boundchanges in cons_varbound.c
6347 - fixed bug in sorting mechanism in cons_xor.c
6348 - fixed wrong (neg)cliquepartition check in cons_knapsack.c when deleting a coefficient
6349 - fixed bug in cons_quadratic: in seldom cases, fixed variables may have been substituted out wrongly in presolve
6350 - fixed bugs in cons_countsols.c w.r.t. collecting feasible solutions and forbidding a found solution
6351 - fixed bug in cons_linear.c: multiaggregated variables were not removed when adding during solve, leading to a failing
6352 assert in tightenBounds due to an unsuccessful bound tightening
6353
6354- Memory:
6355 - fixed bug concerning overflow in memsize calculation in set.c
6356 - fixed memory leak in SoPlex LP interface when requesting an unbounded solution
6357 - fixed memory leak in SoPlex LP interface when solving with LP scaling
6358 - fixed memory leaks in reader of TSP example
6359
6360@section RN201 SCIP 2.0.1
6361*************************
6362
6363Performance improvements
6364------------------------
6365
6366- SCIP with SoPlex as LP solver now uses auto pricing by default (start with devex, switch to steepest
6367 edge after some iterations); this fixes timeouts on instances where devex converges very slowly
6368- fixing lifting of new knapsack items which are negated items of already included items, this could lead to very long presolving
6369- fixed performance issue in presolving w.r.t. to computing the number of new fixings, aggregated,
6370 and so on before a constraint handler presolver is called
6371- in case of adding constraints during pricing with initial flag set to
6372 TRUE, we add now these constraints after the pricing round to the LP
6373- changed parameter values in clique separator in order to avoid very large branch-and-bound trees
6374
6375Interface changes
6376-----------------
6377
6378### New and changed callbacks
6379
6380- allow access of transformed constraints in `SCIP_STAGE_TRANSFORMED`
6381
6382### Changed parameters
6383
6384- replaced parameter `constraints/quadratic/minefficacy` by `constraints/quadratic/minefficacysepa` and `constraints/quadratic/minefficacyenfo`
6385- added possible values `a` and `e` for `constraints/soc/nlpform` to enable automatic choice and convex exponential-sqrt
6386 form for SOC constraint representation in NLP
6387
6388Fixed bugs
6389----------
6390
6391- fixed bug w.r.t. looseobjval; the counting of number of loose variables in the LP data structure was incorrect in case
6392 a variable got aggregated or multi-aggregated
6393- fixed bug in copy method of objvardata which should only create a new `SCIP_VARDATA` if the implemented subclass create
6394 a copy of the given objvardata object
6395- fixed bug in lp.c where in case of objlimit reached and fastmip not all variables where priced because of an incorrect
6396 dual solution
6397- fixed bugs in binpacking example w.r.t. empty struct and not initializing an array
6398- fixed bugs in sepa_clique.c concerning incorrect way to ignore implicit binary variables in cliques and non-active
6399 variables in implications
6400- fixed some bugs w.r.t. to casting pointer arrays
6401- fixed bug in vars.c which handled arrays with parts of original variables during resolving to active variables (using
6402 SCIPvarsGetProbvarBinary) wrong
6403- fixed bug in nlp.c: nlrowSearchQuadElem was using SCIPquadelemSortedFind() incorrectly
6404
6405- Branching:
6406 - fixed assertion w.r.t. to probing during the propagation round of a branch-and-bound node
6407 - fixed computation of node's objective value estimate when branching on continuous variables (see
6408 SCIPtreeCalcChildEstimate(), SCIPtreeBranchVar())
6409 - fixed bug in statistic w.r.t. number of calls for external branching candidates
6410 - fixes to branching on continuous variables
6411
6412- Reader:
6413 - fixed bug in reader_gms.c: linear coefficients for quadratic variables were not printed if they had no
6414 square-coefficient
6415 - fixed bug in reader_mps: indicator constraints do not output the slack variables anymore
6416
6417- Constraints:
6418 - fixed bugs in SCIPcopyConss: copy all active constraints (including disabled ones), *valid was not initialized to TRUE
6419 - fixed bug in debug.c w.r.t. checking of constraints and continuous variables
6420 - fixed bug in cons.c which didn't allow the changing of the separation and enforcement flag of a constraint in the
6421 problem stage
6422 - corrected behavior of the copy function in cons_indicator.c: create artificial linear constraint if linear constraint
6423 was deleted
6424 - fixed bug in cons_indicator.c: presolving cannot delete linear constraints; several other minor bugfixes
6425 - fixed bugs in cons_bounddisjunction where the branching during the constraint enforcement was done incorrectly
6426 - fixed bugs in cons_orbitope.c: orbitopal fixing for the packing case had two bugs; also fixed one wrong assert
6427 - fixed bugs in cons_sos?.c: take average of objestimate
6428 - fixed bug in cons_logicor, implications on none `SCIP_VARTYPE_BINARY` variable were handled wrong
6429 - fixed bug in cons_linear while trying to add a conflict without any variables
6430 - fixed bug in cons_indicator.c: creating constraints in transformed stage is now possible
6431
6432- LP Interface:
6433 - fixed bug w.r.t. memory allocation for all values of a column in lpi_cpx.c
6434 - fixed bugs in SCIPnlpiOracleChgLinearCoefs() and SCIPnlpiOracleChgQuadCoefs() for the case where new coefficients where
6435 added
6436 - fixed bugs in lpi_none.c w.r.t. debug and opt mode
6437 - fixed bug in lpi_cpx.c w.r.t. to wrong handling in case the crossover did not succeed
6438
6439- Heuristics:
6440 - fixed bug in heur_subnlp when initialized starting values of a fixed variable in the NLP of the subscip
6441 - fixed bug in heur_undercover: removed option globalbounds, since we are not allowed to relax bounds at a probing node
6442 - fixed bug in heur_shiftandpropagate where some variables were initialized too late
6443 - fixed numerical issue in some heuristics: nearly-integral values that are between the feasibility and the integrality
6444 tolerance might not have been rounded correctly
6445 - fixed bug in heur_guideddiving: best solution is now copied to avoid deletion in case of many new solutions
6446 - fixed bug in DINS heuristic, information storage for binary variables could lead to bad memory access in column
6447 generation applications
6448 - fixed bug in heur_shiftandpropagate.c: Now, the heuristic checks rows for global infeasibility at the beginning. This
6449 check is only relevant if presolving is disabled.
6450 - fixed bug in heur_subnlp when forbidding a particular combination of integer variables in the main problem
6451
6452@section RN200 SCIP 2.0.0
6453*************************
6454
6455Features
6456--------
6457
6458- added relaxation structure to SCIP, it represents global relaxation information independent from a specific relaxator;
6459 at the moment, it contains information about the relaxation solution stored in the variables: objective value and
6460 validness
6461- SCIP may now be manually restarted
6462- SCIPsolveKnapsackExactly() got a new 12. parameter `SCIP_Bool* success` which stores if an error occured during
6463 solving(normally a memory problem)
6464- SCIP can now handle problems with continuous variables w.r.t. to counting (the projection to the integral variables
6465 are counted)
6466- an XML-parser is available in the src/xml subdirectory
6467- We do not distinguish between block memory for the original and the transformed problem anymore. The same
6468 block memory is now used in both problem stages.
6469- added new sorting method SCIPsortLongPtr(), SCIPsortDownLongPtr() and all corresponding methods
6470- added new sorting method SCIPsortRealIntPtr(), SCIPsortDownRealIntPtr() and all corresponding methods
6471
6472- Heuristics:
6473 - SCIP can now copy instances (e.g. for heuristics)
6474 - new undercover heuristic for MINLPs: fixes variables such as to obtain a linear or convex subproblem and solves this
6475 - primal heuristics may now already be called before presolving, using the new timing point
6476 `SCIP_HEURTIMING_BEFOREPRESOL`. Note that solutions that are added before/during presolving, will be retransformed to
6477 the original space.
6478 - primal heuristics may now be called during presolving, using the new timing point `SCIP_HEURTIMING_DURINGPRESOLLOOP`
6479 - added heuristic zirounding (heur_zirounding.{c,h})
6480 - added heuristic twoopt (heur_twoopt.{c,h})
6481 - added new NLP heuristic (heur_subnlp.{c,h}) which solves the sub-NLP that is obtained by fixing all discrete variables
6482 in the CIP and applying SCIP's presolving
6483 - feasibility pump heuristic now implements all functionality for feasibility pump 2.0
6484
6485- Reader:
6486 - can now read XML-solution files as used by CPLEX
6487 - the MPS reader can now read MIQPs and MIQCPs where a quadratic objective function can be specified by a QMATRIX or
6488 QUADOBJ section and the quadratic part of a quadratic constraint by a QCMATRIX
6489 - the MPS reader can now write quadratic and SOC constraints
6490 - the GAMS reader can now write SOC constraints
6491 - added support for bool_gt, bool_lt, bool_ge, bool_le, bool_ne, bool_not, int_times, int_minus, int_plus, int_negate,
6492 float_times, float_minus, float_plus, float_negate constraints to flatzinc reader
6493 - the LP reader (.lp files) can now read MIQPs and MIQCPs and write quadratic and SOC constraints
6494 - the LP reader (.lp files) and MPS reader can now read semicontinuous variables, they are handled by creating bound
6495 disjunction constraints
6496 - added new reader for polynomial mixed-integer programs (reader_pip.{c,h}) as used in the POLIP
6497
6498- Indicator constraints:
6499 - SCIP can now handle indicator constraints (reading (from LP, ZIMPL), writing, solving, ...) see \ref cons_indicator.h.
6500 - the indicator constraint can now decompose the problem, i.e., not add the linear constraint to the problem if all of
6501 its variables are continuous
6502 - can now read and write indicator constraints in the (extended) MPS format
6503 - cons_indicator tries to adapt solutions to get feasible during check
6504 - cons_indicator allows to store information on other linear constraints that might help to separate cuts
6505
6506- Constraint handlers:
6507 - Solution counting extended to constraint integer programs, this also
6508 includes constraint integer programs which contain continuous variables
6509 - The solution behavior of SCIP can be diversified by randomly permuting constraints and variables or randomly
6510 determining a set of branching variables with a unique high priority
6511 - `negated cliques` (1<=i<=n : sum (x_i) >= n-1) were added and we are using them now inside the knapsack constraint
6512 handler, the cliquepartitioning which is returned by SCIPcalcCliquePartition() contains now integer != 0, negatives ones
6513 indicates a negated clique and positive ones indicates a normal clique
6514 - SCIP is now able to detect in DEBUG-mode whether a constraint or variables which will be added, was also created in
6515 the same scip instance, if not an error is thrown
6516 - cons_knapsack is now able to detect negated cliques due to negated cliques on knapsack constraints
6517 - SCIP is now able to write non-linear opb-files(linear instances with and-constraints)
6518 - New constraint handlers for linking constraints (only Beta), cumulative constraints, and for breaking orbitopal symmetries
6519 - `negated cliques` handling in knapsack constraint handler got changed due to the new method
6520 SCIPcalcNegatedCliquePartition() resulting in new consdata members `negcliquepartition`, `negcliquepartitioned` and
6521 `nnegcliques`; changed SCIPcalcCliquePartition() so all cliquepartitions (calculated by SCIPcalcCliquePartition() or
6522 SCIPcalcNegatedCliquePartition(), which uses the first one) contain again not negative integers
6523 - `and`, `knapsack`, `linear`, `logic`, `or`, `quadratic`, `setpp`, `varbound`, `xor` and `clique` constraint handlers
6524 can handle implicit binary variables
6525 - knapsack constraint handler is now able to pairwise presolving constraints
6526 - constraint handlers `logicor`, `and`, `or` can parse their output
6527 - constraint handler `or` can copy its constraints
6528 - added packing/partitioning orbitope constraint handler for symmetry handling (cons_orbitope.{c,h})
6529 - added constraint handler for second order cone constraints (cons_soc.(c|h))
6530 - added constraint handler cons_linking.{c,h} (see cons_linking.c for more details)
6531 - cons_quadratic can make solutions in CONSCHECK feasible for the quadratic constraints by moving values of linear
6532 variables and passing the modified solution to the trysol heuristic
6533 - constraint handler can now register their upgrade functions for quadratic constraints to cons_quadratic (similar to
6534 LINCONSUPGD)
6535
6536- Separation:
6537 - New separators for oddcycle cuts and Chvatal-Gomory cuts using sub-MIPs
6538 - modified implementation of separation algorithms in cons_knapsack.c according to results of diploma thesis; including
6539 super-additive lifting (disabled)
6540 - uncommented decomposeProblem() in sepa_zerohalf.c (in default settings, not used anyway): was not adapted to the case
6541 that contiuous variables are allowed in a row
6542 - new separator rapid learning (sepa_rapidlearning.{c,h}) that produces conflicts, global bound changes, primal
6543 solutions and initializes inference values for branching
6544 - added Chvatal-Gomory cuts separated with a sub-MIP (sepa_cgmip.{c|h})
6545 - added reader for 'Weigted Boolean Optimization': problems (reader_wbo.{c,h}), this reader needs the reader_opb files
6546 - new separator oddcycle (sepa_oddcycle.{c,h}) separates oddcycle inequalities using the implication/conflict graph and
6547 dijkstra-algorithm based on binary heaps (dijkstra/dijkstra_bh.{c,h})
6548
6549- Branching:
6550 - Branching on externally given candidates, the \ref BRANCH 'branching rules' have a second new callback method
6551 (see type_branch.h for more details): SCIP_DECL_BRANCHEXECEXT(x) can be used to branch on external branching candidates,
6552 which can be added by a user's `relaxation handler` or `constraint handler` plugin, calling SCIPaddExternBranchCand().
6553 - added branchcands for relaxator solution, that can be added by the relaxator and used by branching rules
6554 - added relaxsol to variables, s.t. a relaxator can store a solution on which branching or separation can be done
6555 - SCIP can now branch on relaxation solutions that are either installed to the relaxsol field of the variables or added
6556 to the list of relaxation candidates, e.g., by constraint handlers. Branching on relaxation solutions is performed if
6557 the enforcement resulted in an unresolved infeasibility and there are no LP branching candidates, but before pseudo
6558 solution branching. The branching rules leastinf, mostinf, random and pscost implement the callback for branching on
6559 relaxation candidates.
6560 - SCIP can branch on continuous variables. The branching value x' must not be one of the bounds. Two children (x <= x',
6561 x >= x') will be created.
6562 - the vbc visualization adds the branching type (lower or upper bound change) and the new bound to the node information
6563 - the vbc visualization adds the new bound of the branched variable to the node information
6564
6565- Statistic:
6566 - added statistic information about the first primal solution to SCIP statistic; in the statistic output a new line
6567 appears with this information
6568 - now the statistic displays the number of calls of the feasibility checking method of each constraint handler and the
6569 running time of it
6570
6571- Propagation:
6572 - New rounding and propagation heuristics
6573 - New propagator for variable bounds
6574 - primal heuristics may now be called directly after the node's propagation loop, using the new timing point
6575 `SCIP_HEURTIMING_AFTERPROPLOOP`
6576 - following methods SCIPinferVarUbProp(), SCIPinferVarLbProp(), SCIPinferVarLbCons(), SCIPinferVarUbCons() have a new 6th
6577 parameter `SCIP_Bool force` which allows bound tightening even if the difference to the newbound is below bound
6578 strengthening tolerance
6579 - added propagator for variable lower and upper bounds (prop_vbounds.{c,h}); adjusted cons_varbound.c, var.c, and,
6580 implics.c to work correctly with the new propagator
6581
6582- Nonlinear CIPs:
6583 + Improved constraint handler for quadratic constraints
6584 + New constraint handler for second order cone constraints
6585 + New MINLP heuristics (undercover, subnlp)
6586 + Preliminary support for non-linear relaxations (via expression trees)
6587 + Automatic branching on solutions from arbitrary relaxations and on continuous variables
6588
6589Performance improvements
6590------------------------
6591
6592- improved `settings/emphasis/cpsolver.set` to decrease time per node
6593- reworked access to pseudo solution and inference value of variables in order to reduce function calls
6594- changed default value of parameter `nodeselection/restartdfs/selectbestfreq` to 0; this means if the current node has
6595 no children the node with the best bound is selected (SCIPgetBestboundNode())
6596- added a dual reduction step in cons_knapsack.c
6597- fasten check for common cliques in SCIPcliquelistsHaveCommonClique
6598- SCIP with CPLEX as LP solver now uses quickstart steepest edge pricing as default instead of steepest edge pricing
6599- avoid unnecessary domain propagation and LP resolve at nodes with infeasible LP relaxation
6600- improved zerohalf cut separator: more than one delta is tested for MIR cuts, better handling of dense base
6601 inequalities, faster scaling of fractional coefficients in rows (now enabled), improved parameter settings (presolving)
6602
6603- LP solution:
6604 - in root node, first LP solution is checked for feasibility to avoid expensive setup
6605 - avoided restarting if LP solution is feasible
6606 - separators are not called any longer for an integral initial LP solution
6607
6608Examples and applications
6609-------------------------
6610
6611- New branch-and-price example which includes Ryan/Foster branching (binpacking example)
6612- New example illustrating the use of an event handler (`example/Eventhdlr`)
6613
6614Interface changes
6615-----------------
6616
6617- Enhanced user interface for callable library: manual restarts, predefined settings and many other features
6618- Support of wbo format for weighted PBO problems, IBM's xml-solution format and pip format for polynomial mixed-integer programs
6619- Extended reader for Flatzinc models
6620- new API for 'expressions interpreter': code that evaluates expression trees, including first and second derivatives
6621- NLP solver interface (NLPI) now independent of SCIP like LPI
6622- SCIP can now maintain a central NLP relaxation of the problem (similar to LP)
6623- SCIP can now manage a list of external codes (e.g., LP or NLP solver, ZIMPL)
6624- lp.h/lp.c and the lpi's were changed according to the changes mentioned below.
6625- adding and deletion of rows to the separation storage and to the LP can now be catched by events
6626 (`SCIP_EVENTTYPE_ROWADDEDSEPA`, `SCIP_EVENTTYPE_ROWDELETEDSEPA`, `SCIP_EVENTTYPE_ROWADDEDLP`, `SCIP_EVENTTYPE_ROWDELETEDLP`)
6627
6628### New and changed callbacks
6629
6630- new callback SCIP_DECL_BRANCHEXECRELAX(), together with new parameter in SCIPincludeBranchrule() for branching on a
6631 relaxation solution
6632
6633- Copying a SCIP instance:
6634 - Constraint handlers have two new callback methods. One for copying the constraint handler plugins
6635 SCIP_DECL_CONSHDLRCOPY() and the other for copying a constraint itself, SCIP_DECL_CONSCOPY().
6636 - All plugins, like \ref BRANCH `branching rules` and \ref HEUR `primal heuristics`, have a new callback method (see, e.g.,
6637 type_branch.h and type_heur.h for more details):
6638 - SCIP_DECL_BRANCHCOPY(x), SCIP_DECL_HEURCOPY(x) etc.
6639 - When copying a SCIP instance, these methods are called to copy the plugins.
6640 - The main problem has a new callback method (see type_prob.h for more details) SCIP_DECL_PROBCOPY(x) when copying a
6641 SCIP instance, this method is called to copy the problem's data.
6642 - Variables have a new callback method (see type_var.h for more details) SCIP_DECL_VARCOPY(x) when copying a SCIP
6643 instance, this method is called to copy the variables' data.
6644
6645- Restarts:
6646 - The callback SCIP_DECL_PROBEXITSOL(x) in the main problem has one new parameter (see type_prob.h for more details):
6647 - The parameter `restart` is `TRUE` if the callback method was triggered by a restart.
6648
6649### Deleted and changed API methods
6650
6651- All C++ objects and constructors have a SCIP pointer, now.
6652- added parameter scip to ObjCloneable::clone()
6653- changes in a row can now be catched via row events (SCIPcatchRowEvent(), SCIPdropRowEvent(),
6654 `SCIP_EVENTTYPE_ROWCOEFCHANGED`, `SCIP_EVENTTYPE_ROWCONSTCHANGED`, `SCIP_EVENTTYPE_ROWSIDECHANGED`)
6655- added new parameter `varcopy` to SCIPcreateVar() to add the function for copying variable data
6656- in case of using SCIPwriteTransProblem() the currently (locally) valid problem is written this now also includes the
6657 local constraints
6658
6659- Settings:
6660 - The predefined setting files like `settings/cuts/off.set,aggressive.set,fast.set` have been replaced by
6661 interface methods like SCIPsetHeuristics(), SCIPsetPresolving(), SCIPsetSeparating(), and SCIPsetEmphasis() in
6662 \ref scip.h and by user dialogs in the interactive shell like
6663 `SCIP> set {heuristics|presolving|separating} emphasis {aggressive|fast|off}` or
6664 `SCIP> set emphasis {counter|cpsolver|easycip|feasibility|hardlp|optimality}`
6665 - All functions for setting user parameters of different types like SCIPparamSetBool(), SCIPparamSetChar(),
6666 SCIPparamSetInt(), SCIPparamSetLongint(), and SCIPparamSetString() in pub_paramset.h have a new parameter
6667 `quiet` it prevents any output during the assign to a new value.
6668
6669- NLP:
6670 - NLPIs can now be used without generating a SCIP instance (i.e., do not require a SCIP pointer), code moved into src/nlpi
6671 - NLPIs can now be managed like other SCIP plugins, i.e., they can be included into the SCIP core and accessed by
6672 methods SCIPincludeNlpi(), SCIPfindNlpi(), SCIPgetNNlpis(), SCIPgetNlpis(), SCIPsetNlpiPriority()
6673
6674- Intervalarithmetic:
6675 - method SCIPgetVarPseudocostCurrentRun() now returns the pseudocost value of one branching direction, scaled to a unit
6676 interval, old method now called SCIPgetVarPseudocostValCurrentRun()
6677 - renamed SCIPintervalScalarProductRealsIntervals()/SCIPintervalScalarProduct() by
6678 SCIPintervalScalprodScalars()/SCIPintervalScalprod() and redesigned them in intervalarith.c including new methods
6679 SCIPintervalScalprodScalarsInf/Sup()
6680
6681- Branching:
6682 - The usage of strong branching changed. Now, SCIPstartStrongbranch() and SCIPendStrongbranch() must be
6683 called before and after strong branching, respectively.
6684 - The methods SCIPgetVarPseudocost() and SCIPgetVarPseudocostCurrentRun() in \ref scip.h now return the pseudocost value of
6685 one branching direction, scaled to a unit interval. The former versions of SCIPgetVarPseudocost() and
6686 SCIPgetVarPseudocostCurrentRun() are now called SCIPgetVarPseudocostVal() and SCIPgetVarPseudocostValCurrentRun(), respectively.
6687 - The methods SCIPgetVarConflictScore() and SCIPgetVarConflictScoreCurrentRun() in \ref scip.h are now called
6688 SCIPgetVarVSIDS() and SCIPgetVarVSIDSCurrentRun(), respectively.
6689 - The methods SCIPvarGetNInferences(), SCIPvarGetNInferencesCurrentRun(), SCIPvarGetNCutoffs(), and
6690 SCIPvarGetNCutoffsCurrentRun() are now called SCIPvarGetInferenceSum(), SCIPvarGetInferenceSumCurrentRun(),
6691 SCIPvarGetCutoffSum(), and SCIPvarGetCutoffSumCurrentRun(), respectively. Furthermore, they now return
6692 `SCIP_Real` instead of `SCIP_Longint` values.
6693 - The method SCIPgetVarStrongbranch() has been replaced by two methods SCIPgetVarStrongbranchFrac() and
6694 SCIPgetVarStrongbranchInt().
6695
6696- Copying a SCIP instance:
6697 - Every new callback method resulted in a new parameter of the include function for the corresponding plugin,
6698 e.g., SCIPincludeBranchrule() has two new parameters `SCIP_DECL_BRANCHCOPY((*branchcopy))` and
6699 `SCIP_DECL_BRANCHEXECREL((*branchexecrel))`. In the same fashion, the new callbacks
6700 `SCIP_DECL_VARCOPY` and `SCIP_DECL_PROBCOPY` led to new parameters in SCIPcreateVar() and SCIPcreateProb() in
6701 scip.c, respectively.
6702 - W.r.t. to copy and the C++ wrapper classes there are two new classes. These are `ObjCloneable` and `ObjProbCloneable`.
6703 The constraint handlers and variables pricers are derived from `ObjProbCloneable` and all other plugin are derived from `ObjCloneable`.
6704 Both classes implement the function `iscloneable()` which return whether a plugin is clone able or not. Besides that each class has a
6705 function named `clone()` which differ in their signature. See objcloneable.h, objprobcloneable.h, and the TSP example for more details.
6706 - SCIPincludeHeur() and SCIPincludeSepa() in \ref scip.h, as well as scip::ObjSepa() and scip::ObjHeur(), have a new parameter:
6707 `usessubscip`: It can be used to inform SCIP that the heuristic/separator to be included uses a secondary SCIP instance.
6708 - The argument success in `SCIP_DECL_CONSCOPY` has been renamed to valid.
6709
6710- Heuristics:
6711 - SCIPcutGenerationHeuristicCmir() in sepa_cmir.h has three new parameters:
6712 - `maxmksetcoefs`: If the mixed knapsack constraint obtained after aggregating LP rows contains more
6713 than `maxmksetcoefs` nonzero coefficients the generation of the c-MIR cut is aborted.
6714 - `delta`: It can be used to obtain the scaling factor which leads to the best c-MIR cut found within
6715 the cut generation heuristic. If a `NULL` pointer is passed, the corresponding c-MIR cut will already be
6716 added to SCIP by SCIPcutGenerationHeuristicCmir(). Otherwise, the user can generate the cut and add it to SCIP
6717 on demand afterwards.
6718 - `deltavalid`: In case, the user wants to know the best scaling factor, i.e., `delta` passed is not `NULL`,
6719 `deltavalid` will be `TRUE` if the stored scaling factor `delta` will lead to a violated c-MIR cut.
6720
6721### New API functions
6722
6723- added SCIPcalcNegatedCliquePartition() to scip.c to calculate a clique partition on negations of all given binary
6724 variables
6725- SCIPpermuteArray() that randomly shuffles an array using the Fisher-Yates algorithm
6726- SCIPgetRandomSubset() that draws a random subset of disjoint elements from a given set of disjoint elements
6727- SCIPswapPointers()
6728- SCIPlpiGetSolverDesc() to get a descriptive string of an LP solver (developer, webpage, ...)
6729- SCIPholelistGetNext() to get the next hole of the hole list
6730- SCIPlpRecalculateObjSqrNorm() which is used when the old calculated square norm was unreliable
6731- SCIPpricerIsDelayed() which returns if the pricer is delayed (see pub_pricer.h)
6732
6733- Variables:
6734 - SCIPvarIsBinary() which checks if a variable is (implicit) binary (see var.c for more details)
6735 - SCIPvarGetHolelistOriginal(), SCIPvarGetHolelistGlobal(), SCIPvarGetHolelistLocal() to get the original, global and local holes, respectively
6736 - SCIPvarGetProbvarHole() to tranform a given domain hole to the corresponding active, fixed, or multi-aggregated variable
6737
6738- Restart:
6739 - allow user to trigger a restart during presolving SCIPrestartSolve()
6740 - SCIPrestartSolve() that allows the user to manually restart the solving process
6741 - SCIPisInRestart() to detect whether we are currently restarting
6742
6743- Heuristics:
6744 - for heuristics SCIPheurSetFreq() to change the frequency of the heuristic (pub_heur.h, heur.c)
6745 - SCIPsepaUsesSubscip(), SCIPheurUsesSubscip()
6746
6747- Intervalarithmetic:
6748 - SCIPeventGetHoleLeft() and SCIPeventGetHoleRight() for accessing the left right interval bound of a domain hole added or removed event
6749 - SCIPholelistGetLeft() and SCIPholelistGetRight()to get the left and right interval bounds of the open hole interval
6750 - SCIPintervalAddInf/Sup/Vectors(), SCIPintervalMulInf/Sup() in intervalarith.c
6751
6752- Sorting:
6753 - added SCIPsortPtrPtrLongIntInt(), SCIPsortLongPtrPtrIntInt() and corresponding sorting/inserting/deleting methods in
6754 pub_misc.h and necessary defines in misc.c
6755 - added SCIPsortLongPtrInt() and corresponding sorting/inserting/deleting methods in pub_misc.h and necessary defines in misc.c
6756 - added SCIPsortPtrPtrInt() (and various other) and corresponding sorting/inserting/deleting methods in pub_misc.h and
6757 necessary defines in misc.c
6758 - SCIPsortPtrBool() and corresponding sorting/inserting/deleting methods in pub_misc.h and necessary defines in misc.c
6759
6760- Constraint Handlers:
6761 - SCIPconshdlrGetEnfoConss(), SCIPconshdlrGetNEnfoConss()
6762 - can now forbid upgrading of individual linear constraints (SCIPmarkDoNotUpgradeConsLinear())
6763 - SCIPpermuteProb() that randomly permutes constraints and variables
6764 - SCIPgetResultantOr() which returns the resultant of an `or` constraint
6765 - SCIPmarkDoNotUpgradeConsLinear() in cons_linear.?, which allows to forbid upgrading of linear constraints
6766 - SCIPgetNUpgrConss() which returns the number of upgraded constraints
6767 - SCIPconshdlrGetCheckTime() and SCIPconshdlrGetNCheckCalls() which returns the running time in the feasibility checking of the
6768 corresponding constraint handler respectively the number of calls of the checking method (implemented in cons.c)
6769
6770- Copy:
6771 - SCIPcopy() to clone a SCIP instance
6772 - SCIPcopyPlugins(), SCIPcopyParamSettings(), SCIPcopyVars(), SCIPcopyConss(), SCIPgetVarCopy() to copy
6773 individual parts of a SCIP instance separately.
6774 - SCIPcopyProbData() and SCIPprobCopyProbData() which copies the probdata from a sourcescip to a targetscip
6775
6776- Branching:
6777 - two new functions SCIPgetVarsStrongbranchesFrac()/SCIPgetVarsStrongbranchesInt() for computing strong branching
6778 information for several variables
6779 - SCIPbranchruleGetNRelaxCalls() to get the total number of times, a particular branching rule was called on a relaxation solutions
6780 - SCIPbranchRelax() to branch on a relaxation solution
6781 - SCIPbranchVarVal() to branch on an arbitrary value within the variable's bounds
6782 - SCIPbranchGetBranchingPoint() and SCIPgetBranchingPoint() to select branching point for a variable, e.g.,
6783 ensure branching point is inside the interval for a continuous variable
6784 - SCIPexecRelpscostBranching() in branch_relpscost.{c,h}; this method allows of calling the reliability
6785 pseudo cost branching algorithm for given set of branching candidates from the outside
6786 - SCIPinitVarBranchStats() to initialize the branching statistics (such as pseudo costs, VSIDS, inference values) of a variable
6787 - SCIPselectBranchVarPscost() in branch_pscost.{c,h}; this method selects from a given candidate array a
6788 branching variable w.r.t. pseudo cost branching for relax candidates
6789
6790- Reading, Writing and Parsing:
6791 - SCIPparseVarName() which parses a string in cip-format as a variable name
6792 - SCIPparseVarList() which parses a string as a variable list in cip-format
6793 - the Flatzinc reader can now handle the output annotations of the Flatzinc format; the method SCIPprintSolReaderFzn()
6794 outputs the given solution in Flatzinc format w.r.t. the output annotations
6795 - SCIPprintSolReaderFzn() which prints the best solution in Flatzinc format w.r.t. to the output annotations
6796 in the input file of the flatzinc model
6797 - SCIPwriteVarName() which writes a variable in cip-format to given stream
6798 - SCIPwriteVarsList() which writes an array of variables in cip-Format to given stream
6799 - SCIPwriteVarsLinearsum() which writes an array of variables and coefficients as linear sum in cip-Format to given stream
6800
6801- Copying a SCIP instance:
6802 - SCIPapplyRens() in \ref heur_rens.h has a new parameter `uselprows`. It can be used to switch from LP rows
6803 to SCIP constraints as basis of the sub-SCIP constructed in the RENS heuristic.
6804
6805- Parameters:
6806 - SCIPsetParamsCountsols() which sets the parameter for a valid counting process
6807 - SCIPsetEmphasis() which sets parameter to detect feasibility fast, handle hard LP, solves easy CIPs fast, behaves like a
6808 CP solver, set parameter for a valid counting process; the desired behavior is triggered via a parameter of the function
6809 - SCIPresetParam() to reset the value of a single parameter to its default value
6810
6811- Settings:
6812 - added SCIPsortRealRealRealPtr() and corresponding sorting/inserting/deleting methods in pub_misc.h and necessary defines in misc.c
6813 as basis for the subSCIP, setting ist to TRUE (uses LP rows) will lead to same version as before
6814 - SCIPsetHeuristics(), SCIPsetSeparating(), SCIPsetPresolving() which set the heuristics to aggressive, fast, off, or
6815 default settings, depending on the `SCIP_PARAMSET` parameter
6816 - SCIPsetSubscipsOff() which disables all plugins that uses subscips
6817 - SCIPsepaSetFreq() to set the calling frequency of a separator
6818
6819### Command line interface
6820
6821- added new dialog for setting the SCIP parameters for hardlp, optimality, easy CIP, CP like search
6822- added new dialog for setting the SCIP parameters for feasibility problems `SCIP> set emphasis feasibility`
6823- added new dialog for setting the SCIP parameters for counting `SCIP> set emphasis counting`
6824- added new dialog for setting presolving to aggressive, fast, or off in interactive shell
6825- added new dialog for setting separation to aggressive, fast, or off in interactive shell
6826- added new dialog for writing all solutions which are collected during the counting process (see cons_countsols.{c,h})
6827- added new dialog for setting heuristics to aggressive, fast, or off in interactive shell
6828- added new dialog `display pricers` which displays all included pricers
6829
6830### Interfaces to external software
6831
6832- added interface to CppAD (nlpi/exprinterpret_cppad.cpp)
6833- Improved Xpress, CPLEX, SoPlex interfaces
6834- the SoPlex interface now includes equilibrium scaling on lp's solved from scratch without starting basis
6835- the SoPlex interface can now double check each SoPlex result against CPLEX (lpi_spx.cpp)
6836- the SoPlex interface has the option to restore basis only after entire strong branching phase instead of after each
6837 strong branch (off, because it mostly appears to increase strong branching time and iterations) (lpi_spx.cpp)
6838
6839### Changed parameters
6840
6841- removed parameter `constraints/knapsack/maxnumcardlift` and adapted setting files
6842- changed parameter `lp/fastmip` from boolean to integer, possible values are 0 (off), 1 (medium, default), 2 (full,
6843 must not be used with branch-and-price).
6844
6845### New parameters
6846
6847- `branching/clamp` to set the minimal fractional distance of a branching point to a continuous variable' bounds
6848- `branching/random/seed` to change the initial seed value of the branching rule random
6849- `constraints/indicator/addCouplingCons` that allows to add variable upper bounds if addCoupling is true
6850- `constraints/indicator/enforceCuts` that allows to check for violated cust in enforcement
6851- `constraints/indicator/maxCouplingValue` for the maximal value of the coefficient in a coupling inequality/constraint
6852- `constraints/indicator/noLinconsCon` which controls whether the linear constraint is not explicitly
6853 added to the problem. default is FALSE
6854- `constraints/knapsack/dualpresolving` to switch dualpresolving on/off inside the knapsack constraint handler, default is TRUE
6855- `constraints/knapsack/presolpairwise` that allows pairwise presolving of knapsack constraints, default is TRUE
6856- `constraints/knapsack/presolusehashing` that allows fast pairwise presolving of knapsack constraints, default is TRUE
6857- `heuristics/crossover/dontwaitatroot` that allows to call crossover at root node independently from nwaitingnodes
6858- `heuristics/rens/uselprows` that allows to switch between LP row and SCIP constraints as basis for the
6859 subSCIP, default is TRUE (uses LP rows)
6860- `lp/rowrepswitch` telling simplex solver to switch to row representation of the basis (if possible),
6861 if number of rows divided by number of columns exceeds this value (default value infinity, i.e. never switch)
6862- `lp/threads` to change the number of threads used to solve the LP relaxation (default is 0: automatic)
6863- `misc/lexdualstalling` that turns on the lex dual algorithm if the separation process is stalling
6864- `misc/usevartable` and `misc/useconstable` which turns on/off the usage of hashtables mapping from
6865 variable/constraint names to the variables/constraints; when turned off, SCIPfindVar() and SCIPfindCons() may not be
6866 used; the hashtables can be turned off for subMIPs to improve the performance, default value TRUE
6867- `misc/usesmalltables` which results in using smaller tables for names, cliques and cuts and improves
6868 the performace for smaller instances, default value FALSE
6869- `misc/permutationseed` to change the permutation seed value for permuting the problem after the
6870 problem is transformed (-1 means no permutation)
6871- `reading/zplreader/usestartsol` which allows to switch ZIMPL start solutions off, default value TRUE
6872- `vbc/dispsols` to propose if the nodes where solutions are found should be visualized in the branch and bound tree
6873
6874### Data structures
6875
6876- implemented the data structure and events for global and local domain holes added and removed
6877- new data structures and methods to handle nonlinear expressions in NLPI ({type_, struct_, pub_}expression.{h,c}):
6878 nlpioracle can store and evaluate general NLPs now, nlpi_ipopt can solve general NLPs now
6879
6880Testing
6881-------
6882
6883- minor changes on several evaluation scripts (new statuses: better, solved, sollimit, gaplimit) and short-mode for cmpres.awk
6884- support for FreeBSD (32- and 64-bit) including minor changes in several scripts in the check-directory
6885
6886Build system
6887------------
6888
6889### Makefile
6890
6891- added scripts check_*.sh, evalcheck_*.sh and check_*.awk for blis, glkp, gurobi and symphony (including targets in
6892 Makefile) and slightly modified scripts for cplex, cbc and mosek and cmpres-script
6893- added target `lintfiles` which allows to call flexelint with a list of file, for example, make lintfiles
6894 `FILES=src/scip/prop_vbounds.c`
6895- the NLP solver interfaces and expression interpreter are located in a separate library (libnlpi.*; similar to the lpi
6896 library) and is required to link against the SCIP library also projects that use SCIP via `make/make.project` need to
6897 change their Makefile (!!!): in the $(MAINFILE) target, add $(NLPILIBFILE) behind $(LPILIBFILE) in the dependencies
6898 and add $(LINKCXX_l)$(NLPILIB)$(LINKLIBSUFFIX) to the linker flags
6899- The additional NLPI library requires a change in the Makefile of SCIP's project:
6900 The $(MAINFILE) target now has $(NLPILIBFILE) as additional dependency and the linking
6901 command requires $(LINKCXX_l)$(NLPILIB)$(LINKLIBSUFFIX) as additional argument.
6902- A bug in the Makefiles of older versions of the SCIP examples may cause
6903 data loss. If you have a custom Makefile, please ensure that the target
6904 `clean` is changed as described here:
6905 http://scipopt.org/download/bugfixes/scip-1.2.0/make.txt.
6906
6907Fixed bugs
6908----------
6909
6910- fixed bug in conflict.c in the method conflictsetAddBound()
6911- fixed `bug` in projects Makefiles w.r.t. `make clean`
6912- fixed bug in rapid learning with wrong ordering of dual and primal bound update, primal bound is now updated inside
6913 rapid learning
6914- fixed potential bug in rapid learning with dual reductions
6915- fixed potential bug where SCIPselectSimpleValue() returns a value slightly outside of the given bounds due to rounding
6916 errors (probably cancelation in subtraction in SCIPfindSimpleRational), now use rounding control and check result
6917- fixed bug that SCIP could not be continued after it has been stopped due to a limit
6918- fixed bug in var.c: SCIPvarChgLbOriginal() and SCIPvarChgUbOriginal() cannot access original bounds if the variable is
6919 negated
6920- fixed potential bug with pseudo solution branching on free variables
6921- fixed bug with multiaggregations whose infimum and supremum are both infinite: in such a case multiaggregation is now
6922 forbidden
6923- fixed numerical issue with multiaggregations which are infinite in one direction: value of multiaggregated variable
6924 could have been larger then inifinity
6925- fixed bug w.r.t. of adding a variable bound variable to its self
6926- fixed bug concering the incorrect assumption that every solution computed in SCIPlpGetUnboundedSol() is integral (we
6927 will not branch but return `infeasible or unbounded` like in presolving)
6928- fixed bug while breaking an clique down to their impications (in SCIPcliquetableCleanup() in implics.c) where the
6929 variable was not of vartype `SCIP_VARTYPE_BINARY`, instead of adding an implication we add a variable bound
6930- fixed bug with debugging a solution: during restarts erroneously it was claimed that the primal solution is cut off
6931
6932- Interface:
6933 - fixed bug w.r.t. ObjDialog and displaying the description of the dialog
6934 - fixed bug when aborting pricing with Ctrl-C
6935
6936- LP:
6937 - fixed bug in scip.c w.r.t. to call of conflict analysis for LPs which reached the objective limit in case of diving
6938 - fixed bug with resolving LPs at infeasible root node
6939 - fixed bug in lp.c: in sumMIRRow() rowtoolong was not set correctly
6940 - fixed bug in lp.c w.r.t. objective limit reached and the chosen comparison (fixed buglist entry 40)
6941 - fixed bug in lp.c: if in SCIPlpSolveAndEval() the LP has to be solved from scratch due to numerical troubles, reset
6942 `SCIP_LPPARAM_FROMSCRATCH` to `FALSE` afterwards
6943 - fixed bug in lp.c SCIProwGetObjParallelism() due to a wrong parallelism value which arised from cancellations during
6944 calculation of squared euclidean norm of objective function vector of column variables
6945 - fixed bug in lp.c: SCIPlpGetUnboundedSol() did not ensure that unbounded solution lies withing the bounds of the
6946 variables
6947 - fixed bug in lp.c w.r.t. to the number of `active` pricer
6948
6949- Solve:
6950 - fixed bug in solve.c where relaxation branching candidates were cleared, but the relaxation was still marked solved
6951 and not called again, furthermore, adjusted criterions for solving a relaxation again
6952 - fixed bugs in solve.c: even with LP solving disabled, the root LP was solved in case continous variables are
6953 contained; setting pricing/maxvars(root) to 1 resulted in not calling the pricers
6954 - fixed bug in solve.c: make sure SCIP terminates correctly also when a user interrupt or gap limit is reached, i.e.,
6955 avoid error `pricing was aborted, but no branching could be created!`
6956
6957- Tree:
6958 - fixed bug in tree.c: if an explicit branching point is given, we may not recompute a better centering point
6959 - fixed bug in tree.c: propagate implications on multi-aggregated should not be performed
6960
6961- Constraints:
6962 - corrected several asserts in linear and quadratic constraint handler concerning parsing of CIP format
6963 - fixed bug while deleting redundant variables, which have no influence on changing the feasibility of the linear
6964 constraints, we need to update the sides of the constraint at each step, bug number 51 in bugzilla
6965 - fixed bug in copy procedure of AND constraint handler, negated variables have been copied to their originals
6966 - fixed bug when deleting a constraint where the update was delayed and not processed yet (in cons.c)
6967 - fixed bug in cons_linear.c: binary variables should not be multi-aggregated
6968 - fixed bug in cons_quadratic.c: curvature of bivariate quadratic constraints was not detected correctly
6969 - fixed bug in cons_sos2.c: the branching position was sometimes mistakenly increased
6970 - fixed bug in propagation of cons_sos2.c: the node can be cut off at more places: the previous version was not
6971 sucessfull in this respect
6972 - fixed bug in cons_linear.c:applyFixings() which could lead to lhs/rhs smaller/larger than -/+infinity
6973 - fixed bug in cons_linear.c in detectRedundantConstraints() and corrected old bug fix in SCIProwCreate(): we want lhs
6974 <= rhs to be satisfied without numerical tolerances in order to avoid numerical problems in the LP solver
6975
6976- Knapsack Constraint Handler:
6977 - fixed bug in cons_knapsack.c: mergeMultiples() now detects whether a node can be cut off
6978 - fixed bug in cons_knapsack.c w.r.t. to items with zero weight
6979 - fixed bug in cons_knapsack.c: In SCIPseparateRelaxedKnapsack() not all variables need to be active in deeper regions
6980 of the tree
6981 - fixed bug in cons_knapsack.c and sepa_clique.c: the assumption that implications are always nonredundant and contain
6982 only active variables is not correct anymore as the corresponing vbound might be missing because of numerics
6983
6984- Separation and Cuts:
6985 - fixed bug in cutpool.c: the hashkey computation was not constant over time
6986 - fixed bug in cutpool.c: hashkey of a row changed during the solving process (if a row is made integral after creation,
6987 maxabsval can be invalid when adding it to the pool, but might be recomputed later on)
6988 - fixed bug in sepa_rapidlearning.c, stop processing if there are no binary variables left
6989 - fixed bug in sepa_rapidlearning.c, corrected computation of right dualbound
6990 - fixed bugs in sepa_zerohalf.c, e.g., handling of intscaling and substitution of variable bounds
6991 - fixed bug in sepastore.c in sepastoreApplyLb/Ub being to hard on feasibility decisions
6992 - fixed bug in sepa_flowcover.c: numerical issues while computing candidate set for lambda
6993
6994- LP Interfaces:
6995 - fixed bug in SoPlex autopricing due to which autopricing had behaved like steepest edge pricing so far
6996 - fixed bug in lpi_clp.cpp: SCIPlpiChgBounds() checks if the column status exists in Clp before using it
6997 - fixed wrong assert in Cplex LPI: Due to numerical inaccuracies, a few pivots might be performed after refactorization
6998 - fixed bug concerning assert(!SCIPlpDivingObjChanged(lp)) which was caused by wrong infinity double parameters for
6999 cplex
7000 - fixed makefile system for `OSTYPE=darwin` w.r.t. to CPLEX as LP solver
7001
7002- Presolving:
7003 - fixed bug in cons_setppc: aggregated variables were not correctly removed in presolving
7004 - fixed bug in presolving of linear constraint handler: in redundancy detection, two different numerical epsilons were used
7005 - fixed bug in presolving while not applying a bound change on a variable in a single-variable constraint (e.g. x1 =
7006 0.03) in cons_linear which is too small, that lead to another bound change in presol_trivial which is not allowed, so
7007 now this bound change will be forced
7008 - fixed SCIPvarIsTransformedOrigvar() in var.c (variables generated by presol_inttobinary returned false)
7009 - fixed bug w.r.t. an assert in presol_inttobinary.c; it was assumed that the aggregation which is performed there will
7010 never lead to an infeasibility, this is not true, see comment in presol_inttobinary.c
7011 - fixed bug in presol_trivial.c trying to fix continuous variables, now uses a less stricter comparison to fix variables
7012 - fixed bug in cons_bounddisjunction.c: presolve may have tried to tighten bounds on a multiaggregated variable (now
7013 upgrades to linear constraint)
7014
7015- Reading, Writing and Messages:
7016 - fixed bug while trying to write a MIP where SCIP needs to flush the lp changes first
7017 - fixed potential resource leak when running out of memory while writing files
7018 - fixed bug in reader_zpl.c which appeared using the parameter `reading/zplreader/parameters`
7019 - fixed bugs in flatzinc readers with constraints that exclusively consist of constants
7020 - fixed bug in reader_gms: correct handling of nonstandard bounds on general integer variables
7021 - fixed buglist entry 35, which was caused by a wrong read in correction when the reading buffer was full in
7022 reader_opb.c
7023 - fixed bugs in reader_fzn.c w.r.t. parsing and solution output in Flatzinc format
7024 - fixed bug in reader_fzn.c w.r.t. comment lines
7025 - fixed bug in reader_opb.c w.r.t. comment lines
7026 - fixed bug in message handler w.r.t. to messages which are longer then `SCIP_MAXSTRLEN`
7027
7028- Heuristics:
7029 - fixed bugs do to `HEUR_TIMING SCIP_HEURTIMING_AFTERPROPLOOP` which appeared during repropagation
7030 - fixed bug in trivial heuristic: the locking solution might have falsely initialized some values to zero
7031 - fixed bug in heur_oneopt.c w.r.t. to SCIPtrySol(); it is necessary that the bound of the solution is check otherwise,
7032 infeasible solution could be accepted as feasible
7033 - fixed bug in heur_trivial.c w.r.t. to debug messages after a solution was freed
7034 - fixed bug for `HEUR_TIMING SCIP_HEURTIMING_BEFOREPRESOL` and modifiable constraints
7035 - corrected wrong assert in DINS heuristic when called for an empty problem
7036 - fixed potential bug in OCTANE heuristic with nonbasic solutions
7037 - fixed bug in sub-MIP heuristics with parameter change if some default plugins are not included
7038 - fixed bug in trivial heuristic with bounds that are greater than the heuristic's infinity value
7039
7040Miscellaneous
7041-------------
7042
7043- As the interface contains several additional callback functions and
7044 parameters for plugins, some effort may be required to compile your
7045 own projects with SCIP 2.0. See also `Changes between version 1.2 and 2.0` in the doxygen
7046 documentation for additional information.
7047
7048@page RN12 Release notes for SCIP 1.2
7049
7050@section RN120 SCIP 1.2.0
7051*************************
7052
7053Features
7054--------
7055
7056- adjusted hard memory limit to (soft memory limit)*1.1 + 100mb in check.sh, checkcount.sh, check_cplex.sh,
7057 check_cluster.sh and check_cbc.sh
7058- new presolving step in cons_knapsack.c, same like `simplifyinequalities` in cons_linear.c
7059- now it's possible to write strings with more than `SCIP_MAXSTRLEN` amount of characters in all message.c functions
7060- the current/root lp can be marked to be no relaxation of the current/root problem
7061- added new preprocessing step (mergeMultiples) in cons_setppc.c where equal variables are merged
7062- Black-box lexicographic dual simplex algorithm; can now run lexicographical dual algorithm (parameter `lp/lexdualalgo`)
7063
7064- Bounds:
7065 - SCIP now has `lazy bounds`, which are useful for column generation: see @ref PRICER_REMARKS `pricer remarks` for an explanation.
7066 Each variable has now two additional `SCIP_Real` parameter which define a lazy lower and upper bound; lazy means that
7067 there exists constraints which implies these (lazy) bounds. If the lazy lower or upper bound is greater or less than
7068 the local lower or upper bound, respectively, then the corresponding bound is not put into the LP. The bounds are set
7069 to minus and plus infinity per default which yields the same behavior as before. With the methods SCIPchgVarLbLazy()
7070 and SCIPchgVarUbLazy() these bounds can be set. This is of interest if SCIP gets used as a branch-and-price
7071 framework. Attention! The lazy bounds need to be valid for each feasible LP solution. If the objective function
7072 implies bounds on the variables for each optimal LP solution, but these bounds may be violated for arbitrary LP
7073 solutions, these bounds must not be declared lazy!
7074 - interval arithmetic functions can work with unbounded intervals added new functions to allow more operations on
7075 intervals, including solving quadratic interval equations
7076
7077- Branching:
7078 - extended hybrid relpscost branching rule by usage of the average length of conflicts a variable appears in
7079 - `early branching`-functionality added: in a branch-and-price code, the user can stop pricing at a node although there
7080 may exist variables with negative reduced costs. In this case, the lp-lowerbound will not be used. The pricer has,
7081 however, the option to return a lower bound. This can be useful for column generation.
7082
7083- Constraints:
7084 - Copy constructors and i/o functionality for constraints: all linear type constraint handlers are able to copy
7085 constraints using the function SCIPgetConsCopy() in scip.h
7086 - the linear constraint handler is able to parse a string in CIP format and create a corresponding linear constraint
7087 - Constraint handler for indicator constraints and parsing them from *.lp and *.zpl files
7088 - the indicator constraint can now try to produce a feasible solution (via heur_trysol)
7089 - one can now write indicator constraints in LP-format
7090 - added constraint handler for quadratic constraints
7091
7092- Cuts:
7093 - added new version of zerohalf cuts from Manuel Kutschka
7094 - added multi-commodity-flow cut separator
7095
7096- Heuristics:
7097 - Heuristics which are applied before root LP
7098 - added heuristic that performs a local search in an NLP (takes only linear and quadratic constraints into account so far)
7099 - added heuristic that gets a solution from other components and tries it (heur_trysol.?)
7100 - new trivial heuristic: tries zero solution, lower and upper bound solution and some variable lock based fixing
7101 - added new timing point, `SCIP_HEURTIMING_DURINGPRICINGLOOP`, for calling heuristics; If this timing point is used the
7102 corresponding heuristics is called during the pricing loop of variables; we also added this timing point to
7103 heur_simplerounding.{h,c} which has the effect that a LP solution which satisfies all integrality conditions during
7104 the pricing loop is detected
7105
7106- Interfaces:
7107 - added first version of an interface to NLP solvers (type_nlpi.h, struct_nlpi.h, nlpi.h, nlpi.c, nlpi_oracle.h, nlpi_oracle.c)
7108 - Preliminary support of non-convex MIQCPs: Constraint handler for quadratic constraints, NLP heuristic and
7109 Ipopt interface, see \ref cons_quadratic.h.
7110 - There are LP-interfaces to QSopt and Gurobi (rudimentary).
7111
7112- Reader and Writer:
7113 - added reader and writer for FlatZinc models (reader_fzn.{c,h})
7114 - added writer for GAMS models (reader_gms.{c,h})
7115
7116Performance improvements
7117------------------------
7118
7119- Enhanced MCF cuts: stable version, used by default
7120- replaced some function calls in loop conditions
7121- in sepa_cmir.c, if mksetcoefs is invalid for delta=1 no other values of delta are tested anymore
7122- changed the timing of the feasibility pump in case of pricing
7123- removed changing of update rule to `ETA` from standard soplex update `Forrest-Tomlin` in lpi_spx.cpp
7124- improved memory usage in heur_octane.c
7125- improved reading time of opb-files, due to using a hashtable for all `and`-constraints
7126- improved performance of merging variables in mergeMultiples() in cons_knapsack.c
7127- improved performance in tightenWeightsLift() and SCIPseparateRelaxedKnapsack() in cons_knapsack.c, due to now
7128 sparse-cleaning `global` arrays instead of using BMSclearMemory... functions for cleaning local arrays each time
7129- improved performance in SCIPcliquelistRemoveFromCliques()
7130- improved performance in SCIPcalcCliquePartition()
7131- improved performance in SCIPvarGetActiveRepresentatives() in var.c
7132
7133- Presolving:
7134 - improved pairwise presolving in cons_and.c due to using a hashtable
7135 - improved pairwise presolving in cons_xor.c due to using a hashtable
7136
7137Interface changes
7138-----------------
7139
7140- A significant change for C++ users is that all include files of SCIP
7141 automatically detect C++ mode, i.e., no `extern `C`` is needed anymore.
7142- Reader for Flatzinc and GAMS models
7143
7144### New and changed callbacks
7145
7146- The callback SCIP_DECL_PRICERREDCOST(x) in the \ref PRICER `pricers` has two new parameters:
7147 + A `result` pointer determines whether the pricer guarantees that there exist no more variables. This allows for early branching.
7148 + A pointer for providing a lower bound.
7149
7150- The \ref CONS `constraint handlers` have two new callback methods (see type_cons.h for more details):
7151 + SCIP_DECL_CONSCOPY(x): this method can be used to copy a constraint.
7152 + SCIP_DECL_CONSPARSE(x): this method can be used to parse a constraint in CIP format.
7153
7154### Deleted and changed API methods
7155
7156- SCIPcalcMIR() in scip.h has two new parameter `mksetcoefsvalid` and `sol`. The parameter `mksetcoefsvalid` stores
7157 whether the coefficients of the mixed knapsack set (`mksetcoefs`) computed in SCIPlpCalcMIR() are valid. If the mixed
7158 knapsack constraint obtained after aggregating LP rows is empty or contains too many nonzero elements the generation of the
7159 c-MIR cut is aborted in SCIPlpCalcMIR() and `mksetcoefs` is not valid. The input parameter `sol` can be used to separate a
7160 solution different from the LP solution.
7161- new parameter `set` in SCIPconsSetInitial().
7162- some interval arithmetic method take an additional argument to denote which value stands for infinity in an interval
7163
7164- Variables:
7165 - SCIPgetVarClosestVlb() and SCIPgetVarClosestVub() in scip.h have a new parameter `sol`. It can be used to obtain the closest
7166 variable bound w.r.t. a solution different from the LP solution.
7167 - new parameters `lowerbound` and `result` in type_pricer.h: lowerbound can save a lower bound computed by the pricer,
7168 result indicates whether the pricer guarantees that there exist no more variables if no variable was found
7169
7170### New API functions
7171
7172- new methods to deactivate a pricer SCIPdeactivatePricer() in scip.c
7173- new methods in pub_misc.h/misc.c to access hash map lists and elements of a hash map list and to clear all entries in a hash map
7174- SCIPsetProbName() to set problem name in scip.h/c (SCIPprobSetName() in prob.h/c)
7175
7176- Objective:
7177 - SCIPgetTransObjscale() and SCIPgetTransObjoffset() in scip.c
7178 - SCIPaddObjoffset() in scip.h; sets offset of objective function
7179 - SCIPgetOrigObjoffset() in scip.h; returns the objective offset of the original problem
7180 - SCIPgetOrigObjscale() in scip.h; returns the objective scale of the original problem
7181
7182- Constraints:
7183 - detectRedundantConstraints() in cons_xor.c and necessary hash-functions for fast pairwise presolving
7184 - SCIPparseCons() in scip.h; parses constraint information (in cip format) out of a string
7185 - SCIPgetConsCopy() in scip.h; which copies a constraint of the source SCIP
7186
7187- Relaxation:
7188 - SCIPisLPRelax() and SCIPisRootLPRelax() in scip.c and scip.h returning whether the current/root LP is a
7189 relaxation of the current/root problem and thus defines a valid lower bound
7190 - SCIPlpSetIsRelax() and SCIPlpSetRootLPIsRelax() in lp.c and lp.h to set the information, whether the lp is a valid relaxation;
7191 this information is per default set to true and constraint be used. The aggregated version has only 2 linear constraints the
7192 default linearization has nvars + 1
7193
7194- Sort:
7195 - extended the sort template functions in sorttpl.c with a `five` array; now it possible to used this template to sort
7196 up to five arrays
7197 - new interface methods SCIPcolSort(), SCIProwSort(), SCIPcolGetIndex()
7198 - added SCIPsortPtrPtrLongInt() and corresponding sorting/inserting/deleting methods in pub_misc.h and necessary defines
7199 in misc.c
7200
7201- Variables:
7202 - SCIPprintNodeRootPath() in scip.h This method prints all branching decisions on variables from the root to the given node
7203 - SCIPnodeGetParentBranchings(), SCIPnodeGetAncestorBranchings(), SCIPnodeGetAncestorBranchingPath(); These methods return
7204 the set of variable branchings that were performed in the parent node / all ancestor nodes to create a given node
7205 - SCIPchgVarLbLazy() and SCIPchgVarUbLazy() in scip.h; These methods can be used to change the lazy lower or
7206 upper bound of a variable; This might has the consequences that the bounds of the corresponding variable is not in
7207 LP. This is the case if the lazy lower or upper bound is greater or less than the local lower or upper bound, respectively
7208 - SCIPvarGetLbLazy() and SCIPvarGetUbLazy() in pub_var.h; These methods return the lazy lower or upper bound, respectively
7209 - SCIPvarCompareActiveAndNegated() and SCIPvarCompActiveAndNegated() in pub_var.h for comparing variables
7210 negated, active or fixed the same way
7211 - SCIPparseVars() in scip.h; parses variable information (in cip format) out of a string
7212 - SCIPgetNFixedonesSetppc() and SCIPgetNFixedzerosSetppc() in cons_setppc.{h,c}; these methods returns
7213 current (local) number of variables fixed to one/zero in the given setppc constraint
7214 - SCIPgetVarConflictlengthScore(), SCIPgetVarAvgConflictlength(), SCIPgetAvgConflictlengthScore() and their pendants for the current run
7215 - added function SCIPvarsGetProbvarBinary() in pub_var.h; gets active, fixed, or multi-aggregated problem variables of
7216 binary variables and corresponding negated status
7217
7218### Interfaces to external software
7219
7220- LP Interfaces:
7221 - heavily revised Mosek interface
7222 - new interface to QSopt due to Daniel Espinoza
7223 - First version of LP interfaces to Gurobi and QSopt
7224 - Major performance improvements in LP interfaces to Clp, Mosek and SoPlex
7225
7226- External Software:
7227 - adjusted interface to ZIMPL (reader_zpl.{c,h} for ZIMPL version 2.10; this interface should also work with older ZIMPL versions
7228 - Adjusted interface to Zimpl version 3.0.0
7229 - added first version of an interface to Ipopt (only QCP, no deletion of vars/cons allowed; nlpi_ipopt.(h|c))
7230
7231- SCIP Interfaces:
7232 - On http://code.google.com/p/python-zibopt/source/checkout you find a beta
7233 version of a python interface to SCIP implemented by Ryan J. O'Neil.
7234
7235### Changed parameters
7236
7237- removed parameter `constraints/and/initiallp` since it is not needed anymore;
7238- set parameter `constraints/and/sepafreq` default value to 1
7239- display character of oneopt heuristic changed to `b`
7240
7241### New parameters
7242
7243- `branching/relpscost/advanced/conflenscore`, default value 0.001
7244- `constraints/and/aggrlinearization` in cons_and.c, aggregated version of the linearization
7245- `constraints/and/enforcecuts` in cons_and.c, should cuts be separated during LP enforcing?
7246- `constraints/and/presolusehashing` in cons_and.c, should pairwise presolving use hashing?, default TRUE
7247- `constraints/countsols/sollimit` in cons_countsols.c, counting stops, if the given number of solutions were found (-1: no limit)
7248- `constraints/xor/presolusehashing` in cons_xor.c, should pairwise presolving use hashing?, default TRUE
7249- `heuristics/oneopt/duringroot`, default value TRUE
7250
7251Build system
7252------------
7253
7254### Makefile
7255
7256- extend Makefile to link against Ipopt if `IPOPT=true` is set
7257
7258Fixed bugs
7259----------
7260
7261- fixed wrong use of pointer in lp.c
7262- fixed bug with array dimension not reset to zero when array is freed in pseudoobj propagator
7263- fixed bug with enforcement of pseudo solutions: if pseudo solution is choosen because LP hit a limit, it has to be
7264 enforced in any case
7265- fixed potential bug in coloring example: SCIPcreateChild() is now given an estimate in terms of the transformed
7266 problem by SCIPgetLocalTransEstimate(), no longer the estimated original problem value. Also clarified this in the
7267 comments for SCIPcreateChild()
7268- fixed compiler warning `warning: dereferencing type-punned pointer will break strict-aliasing rules` which resuts in
7269 scip-crashes with gcc version 4.4.0
7270- adjusted assert in var.c
7271- fixed bug in SCIPvarGetActiveRepresentatives() in var.c
7272- fixed bug with objective limit in lp.c: previously the infinity value of SCIP was used as default - now the value of
7273 LPI is used. In the earlier version in many cases the problems where never infeasible.
7274- added and adjusted some asserts, initialized some values
7275- increased the numerical stability of coefficient tightening for Big M formulations
7276- fixed bug with incorrect pseudo activities when objective of a variable switches sign in linear constraint handler
7277- fixed bug with empty constraints in several writing routines
7278- fixed `GGT-Kaibel-Bug` in var.c, prop_pseudoobj.c and cons_varbound.c that occured while computing new values using
7279 infinity values
7280
7281- Bounds:
7282 - fixed bug in coefficient tightening with infinite bounds
7283 - fixed bug in solve.c: in case lowerbound >= upperbound, SCIPsolveIsStopped() returned `SCIP_STATUS_GAPLIMIT`
7284
7285- Nodes:
7286 - fixed bug in SCIPsolveNode() concerning the case that the time limit was hit while solving the LP relaxation of a
7287 subproblem which is already an LP (branching on pseudo solution is not possible)
7288 - fixed bug in vbc tools concerning of marking probing nodes
7289 - fixed bug in solve.c with nodes which are marked to be repropagated while enforcement
7290
7291- Variables:
7292 - fixed possible infinite loop while multiaggregating a variable in var.c
7293 - fixed bug in SCIPgetSolVals() similar to SCIPgetSolVal(): try to get original variables of transformed ones if the
7294 solution lives in original space
7295
7296- Pricing:
7297 - fixed potential bug: restarts are now only done if no active pricers exist
7298 - fixed bug in SCIPlpSolveAndEval(): if fastmip and pricers enabled and objlimit was reached but CPLEX did not perform
7299 the final pivot step in order to exceed the objlimit, do one additional simplex step with pricing strategy steepest
7300 edge, if this doesn't suffice, turn off fastmip temporarily and solve again. Also consider solstat of the new
7301 solution.
7302 - fixed bug with invalid pseudo solution (lower bound was always >= 0) when using pricing.
7303 - fixed bug in SCIPfreeProb() in scip.c: all pricers are deactivated now
7304
7305- Memory:
7306 - now frees debug memory
7307 - fixed bug with exponential complexity for reallocating memory in SCIPvarGetActiveRepresentatives() in var.c
7308 - fixed casting of void* pointers in memory.h for C++, adjusted the same for C in memory.h and due to that adjusted all
7309 header files(set whole files in extern `C`) and cpp-files(removed unnecessary extern `C` lines)
7310 - removed memory leak in connection with freeing branch and bound nodes: focusnode was not freed if both children could
7311 be cut off due to bounding
7312
7313- Reading and Writing:
7314 - corrected bug in reader_lp.c: earlier read bounds were thrown away (implementation was not conforming to standard)
7315 - fixed bug in reader_lp.c with respect to constraint and variable names which start with two or more dots `..`
7316 - fixed bug in all readers w.r.t. SCIPgetProbvarLinearSum()
7317 - fixed bug in reader_mps.c with respect to corrupted files
7318 - fixed bug in reader_mps.c with respect to writing transformed problems
7319 - changed wrong writing of mps files due to constraints without any name
7320 - fixed a bug during reading debug solution file
7321 - fixed bug in case of reading an objective function in opb format with multiple occurrences of the same variable
7322 - fixed bug in case of reading an objective function in lp format with multiple occurrences of the same variable
7323 - fixed a wrong fix of a reading bug, which was in reality a writing bug in MPS format; integer variables in mps format
7324 without bounds are binary variables, if the bound of an integer variable is infinity you have to write this bound
7325
7326- Separation:
7327 - fixed bug in sepa_cmir.c, sepa_mcf.c and sepa_flowcover.c: sol different to LP solution is now separated
7328 - corrected two asserts in sepa_redcost.c (reduced costs can be negative for fixed variables: qsopt uses this)
7329 - fixed bug in sepa_zerohalf.c; replacement of own sorting functions by template functions was incorrect
7330 - fixed bug in var.c, cons_knapsack.c and sepa_flowcover.c: variable bounds corresponding to implication are not
7331 generated if coefficient is large, variable bounds with large coefficients are ignored for construction of knapsack
7332 and snf relaxations
7333 - fixed bug in sepa_impliedbound.c concerning redundant implications
7334
7335- Cuts:
7336 - fixed bug in sepa_cmir.c concerning uninitialized mksetcoefs (if MIR-cut generation is aborted because the aggregated
7337 constraint is empty or contains too many nonzero elements mksetcoefs is invalid)
7338 - interrupts optimization process if a node will be cutoff, which allows the solution
7339 - fixed bug in sepa_impliedbounds.c and sepa_intobj.c: if separating a sol, this sol is now also given to SCIPaddCut()
7340 so that the efficacy of the cut is now computed correctly
7341 - fixed bug in solve.c caused by integer overflow due to setting the number of cuts to INT_MAX
7342
7343- Presolving:
7344 - fixed wrong result in check.awk, if infeasible problems are stopped in presolving
7345 - fixed exponential calculation of solution values during check of original solution, therefore changed
7346 SCIPvarGetActiveRepresentatives() in var.c and flattened all multiaggregated vars at the end of presolving in
7347 exitPresolve()
7348 - fixed bug with wrong abort criterion in presolving
7349 - fixed bug in presol.c caused by not reseting presolver-wasdelayed status
7350 - fixed bug in SCIPconsSetInitial() that occurred in pairwise presolving: add or delete constraint in initconss when
7351 changing the initial flag
7352
7353- Constraints:
7354 - fixed bug in cons.c caused by not resetting conshdlr data after restart
7355 - fixed memory error in cons_countsols.c
7356 - fixed assert in cons_and.c method SCIP_DECL_CONSINITSOL(consInitsolAnd)
7357 - fixed bug in cons_countsols.c we respect to warning message that `The current parameter setting might cause ...`
7358
7359- Knapsack Constraint Handler:
7360 - fixed wrong assert in cons_knapsack.c and handled a special this case in simplifyInequalities()
7361 - fixed some bugs in simplifyInequalities() in cons_knapsack.c
7362 - fixed bug in mergeMultiples() in cons_knapsack.c
7363 - adjusted ConsData and ConsHdlrData in cons_knapsack.c
7364 - fixed compiler warning caused by no initialization of two integer in cons_knapsack.c
7365 - fixed bug in cons_knapsack.c caused by having a multi-aggregated variable in a knapsack constraint, now applyFixing is
7366 able to resolve a binary multi-aggregation with integral values
7367
7368- Linear Constraint Handler:
7369 - fixed infinity loop in simplify inequalities in cons_linear.c
7370 - fixed bug in cons_linear.c: do not select variable as slack variable for multiaggregation in convertLongEquality if it
7371 has been marked as not-multiaggregable
7372 - fixed bug in cons_linear.c: also do not multiaggregate variables in dual preproccessing if it has been marked as
7373 not-multiaggregable
7374 - fixed bug in cons_linear.c: slight decrease of epsilon in order to make sure that scaled coefficients are really
7375 integral
7376 - fixed bug in chgRhs() and chgLhs() of cons_linear.c: after changing lhs or rhs of a constraints lhs <= rhs has to be
7377 satisfied without numerical tolerances
7378
7379- Heuristics:
7380 - added and changed some SCIPisStopped() calls in several heuristics
7381 - fixed bug in oneopt heuritic with start solution which has become infeasible due to global bound changes
7382
7383- Interfaces:
7384 - corrected several bugs in the Clp-interface concerning return values
7385 - fixed potential interface bug: time limits of 0.0 are not anymore passed to the LP solver, which may have caused
7386 errors
7387
7388@page RN11 Release notes for SCIP 1.1
7389
7390@section RN110 SCIP 1.1.0
7391*************************
7392
7393Features
7394--------
7395
7396- SCIP can now count integer feasible solutions for IPs/CIPs (without continuous variables) (see SCIPcount())
7397- check.awk now uses TeX package supertabular which supports automatic pagebreak
7398- struct `SCIP_Stat` has now two additional variables: `nprobboundchgs`, `nprobholechgs`; these are used to fix the domain
7399 reduction counts in sepa.c, cons.c, branch.c and prop.c; this means, that now the domain reduction counts are reduced
7400 by those domain reduceds which are preformed during probing
7401- added capabilities to flatten the (multi)-aggregation graph of variables
7402- pseudoobj propagator now also propagates the global lower (dual) bound
7403- new heuristic DINS (distance induced neighborhood search by Ghosh)
7404
7405- Output:
7406 - SCIP can now output a picture of the constraint matrix in PPM format.
7407 - output of real values is now done with 15 digits after the decimal point
7408 - Extended the capabilities of SCIP to output problems in different formats (LP, MPS, CIP, ...). You can output the original and
7409 transformed problem. Furthermore, generic names can be given to the variables and constraints.
7410 - The feasibility test for solutions at the end of the execution now outputs more useful information.
7411 This made some changes in the interface of constraint handlers necessary.
7412
7413- Presolving:
7414 - added predefined settings file presolving/aggressive.set
7415 - new presolver boundshift (presol_boundshift.{c,h}); this presolver is currently turned off with default parameter setting
7416
7417- Constraints:
7418 - linear constraint handler now detects continuous variables that are implicit integer in dual presolve
7419 - replaced some old sorting methods in cons_knapsack.c, heur_octane.c, sepa_flowcover.c and presol_probing.c through
7420 SCIPsort...() interfaces, adjusted misc.{c,h} and pub_misc.h for these changes
7421 - cons_countsols.c is now able to store the collected solution if required
7422 - added first version of SOS type 1 constraint handler (cons_sos1.{c,h})
7423 - added first version of SOS type 2 constraint handler (cons_sos2.{c,h})
7424 - less aggressive scaling in linear constraint handler presolve to improve numerics
7425 - added first version of constraint handler cons_countsols.{c,h}
7426
7427- Reader:
7428 - added ccg-reader (weighted column connectivity graph)
7429 - added reader for pseudo-Boolean problems (reader_opb.{c,h})
7430 - the ZPL reader is now able to pass a starting solution to SCIP
7431 - the MPS reader is now able to write a problem in MPS format
7432 - the ZIMPL reader now understands SOS type 1 and 2 constraints
7433 - the LP reader reads SOS constraints of type 1 and 2
7434 - the MPS reader reads the SOS section (but cannot yet handle `MARKERS`)
7435
7436- LPI:
7437 - The SoPlex LPI can now write basis files.
7438 - revised lpi_clp.cpp (many small changes, in particular writing and reading of bases)
7439 - added FASTMIP settings in lpi_clp.cpp that try to improve the performance of Clp as much as possible
7440
7441- Cuts and Separation:
7442 - the c-MIR separator now also tries to get rid of implicit integer variables by aggregation
7443 - allow cut selection based on support of inequality in orthogonality computation
7444 - disabled zerohalf cuts by default
7445 - adjusted all predefined settings files, e.g., `settings/cuts/fast.set`, such that they are consistent wrt removed,
7446 added and changed parameter values of scip.
7447 - New cutting plane separator MCF (beta version).
7448 - new separator sepa_zerohalf.{c,h}; separates {0,1/2}-Cuts according to Caprara and Fischetti
7449
7450Performance improvements
7451------------------------
7452
7453- heavily decreased the usage of SCIPisStopped(), which costs system time
7454- small performance improvement of c-MIR aggregation heuristic
7455- reworked strong branching in lpi_clp.cpp (scaling works now, bounds can be trusted)
7456
7457- Constraints:
7458 - The preprocessing has been revised. It now applies bound computations in a numerically more stable way. The pairwise
7459 comparison of linear, logicor, and setppc constraints has been improved.
7460 - better branching in SOS1/SOS2 constraints
7461 - fixed performance bug with large number of unnamed constraints that will kill the name hash table (now, unnamed
7462 constraints are not put into the hash table)
7463
7464- Cuts and Separation:
7465 - improved the performance of SCIPcalcMIR() and SCIPcalcStrongCG() by exploiting sparsity
7466 - improved performance of SCIPvarGetLPSol(), which affects many parts of the code, in particular Gomory and strong CG cuts
7467 - do not calculate MIR and StrongCG cut aggregations if number of nonzeros in aggregated row is too large
7468
7469- Presolving:
7470 - improved pairwise presolving in cons_linear.c: reduced cache misses, reduced number of SCIPisStopped() calls and
7471 included detecting of redundant constraints with hash table in advance
7472 - tighter memory limits in knapsack presolve lifting procedure to avoid overly expensive presolving
7473 - included detecting of redundant constraints with hash table in advance in cons_logicor.c and limit other pairwise
7474 presolving
7475 - included detecting of redundant constraints with hash table in advance in cons_setppc.c and limit other pairwise
7476 presolving
7477 - limit pairwise presolving in cons_linear.c
7478
7479Examples and applications
7480-------------------------
7481
7482- Added an example for the graph coloring problem in `examples/Coloring`, showing the usage of column generation.
7483- added SOS2 example
7484- extended TSP example
7485
7486Interface changes
7487-----------------
7488
7489### New and changed callbacks
7490
7491- New callback method SCIP_DECL_READERWRITE(x) in type_reader.h; this method is called to write a problem to file
7492 stream in the format the reader stands for; useful for writing the transformed problem in LP or MPS format. Hence,
7493 also SCIPincludeReader() has changed.
7494- The callback \ref CONSCHECK (SCIP_DECL_CONSCHECK()) in the constraint handlers now has a new parameter `printreason` that tells
7495 a constraint handler to output the reason for a possible infeasibility of the solution to be checked using
7496 SCIPinfoMessage(). Have a look at one of the constraint handlers implemented in SCIP to see how it works. This
7497 methodology makes it possible to output the reason of a violation in human readable form, for instance, for the check
7498 at the end of a SCIP run, where the obtained best solution is checked against the original formulation.\n This change
7499 often has little effect on C-implementations, since this parameter can be safely ignored with respect to the
7500 correctness of the code. The corresponding C++ method scip::ObjConshdlr::scip_check(), however, has to be extended
7501 and will not compile otherwise.
7502- added new LPI pricing option `SCIP_PRICING_LPIDEFAULT`, such that every LP interface can set the default pricing
7503 strategy on its own (`auto` is not useful for this, because for CPLEX, for example, SCIP seems to be worse with `auto`
7504 then with `steepest edge`)
7505- Added user pointer to callback methods of hash table, see pub_misc.h.
7506
7507### Deleted and changed API methods
7508
7509- SCIPgetVarRedcost() now returns 0 for variables that have been aggregated out or removed in presolving.
7510 reduced cost in case of infeasible LPs)
7511- new parameter `maxfrac` for SCIPcalcStrongCG()
7512- new parameter `maxmksetcoefs` for SCIPcalcMIR() and SCIPcalcStrongCG() methods
7513- new parameter `conshdlrname` in SCIPincludeLinconsUpgrade()
7514
7515- Problem:
7516 - new parameters `extension` in SCIPreadProb() defining a desired file format or `NULL` if file extension should be use
7517 - New parameters `extension` and `genericnames` in SCIPprintTransProblem(), SCIPprintOrigProblem(),
7518 SCIPwriteOrigProblem(), and SCIPwriteTransProblem() defining the requested format or `NULL` for default CIP format
7519 and using generic names for the variables and constraints. Examples are
7520 - SCIPprintTransProblem(scip, NULL, NULL, TRUE) displays the transformed problem in CIP format with
7521 generic variables and constraint names
7522 - SCIPprintOrigProblem(scip, NULL, `lp`, FALSE) displays the original problem in LP format with
7523 original variables and constraint names.
7524
7525- Sorting:
7526 - expand sorttpl.c by some parameters
7527 - changed some names for sorting methods
7528 - replaced sorting methods SCIPbsort...() by faster (quicksort/shellsort) algorithms SCIPsort...() Note that the order
7529 of the parameters has been changed to simplify the template code in sorttpl.c!
7530
7531- Checking:
7532 - SCIPcheckSolOrig() is restructured. The last two parameters have changed. They are now bools indicating
7533 whether the reason for the violation should be printed to the standard output and whether all violations should be
7534 printed. This reflects the changes in the constraint handlers above, which allow the automation of the feasibility
7535 test. The pointers to store the constraint handler or constraint are not needed anymore.
7536 - the parameter list of the method SCIPcheckCons() (scip.h) has changed; the new advatage is, that SCIP can print the
7537 reason for the violation of a constraint as for as the constraint handler supports that
7538 - the parameter list of the method scip_check() (objconshdlr.h) has an additional parameter `printreason` see for
7539 explanation the previous point
7540
7541### New API functions
7542
7543- LPI now has a function SCIPlpiGetSolverPointer() that returns a solver dependent pointer. This can be used to directly
7544 access the LP solver. This should, of course, only be used by people that know exactly what they are doing.
7545- added capabilities to avoid multi-aggregation of a single variable by setting a corresponding flag (SCIPmarkDoNotMultaggrVar())
7546- SCIPgetProbvarLinearSum()
7547- SCIPgetResultantAnd() which returns the resultant variable of an `and` constraint
7548- SCIPchgChildPrio() to change the node selection priority of the given child
7549- SCIPconsGetPos()
7550- SCIPrepropagateNode() to mark a node for repropagation
7551- SCIPcount() (in cons_countsols.h) for counting all feasible solution of a given CIP
7552- SCIPcreateRootDialog() (in dialog_default.h) which creates a root dialog
7553- SCIPgetVectorEfficacyNorm()
7554- SCIPseparateRelaxedKnapsack() in cons_knapsack.h
7555- SCIPgetCutoffdepth() which returns the depth of first node in active path that is marked being cutoff
7556- SCIPflattenVarAggregationGraph()
7557- SCIPclockGetLastTime()
7558- SCIPcalcHashtableSize() to get a reasonable hash table size
7559- SCIPgetVarFarkasCoef() and SCIPgetColFarkasCoef() to get the farkas coefficient of a variable (analogon of
7560- SCIPgetRepropdepth() to get the depth of first node in active path that has to be propagated again
7561- SCIPmajorVersion(), SCIPminorVersion() and SCIPtechVersion() returning the corresponding version
7562
7563- Read, Write and Print:
7564 - SCIPprintSysError() which encapsulates the strerror_r calls, the NO_STRERROR_R flag switches between the use
7565 of strerror_r and strerror inside
7566 - SCIPsnprintf() safe version of snprintf (and sprintf)
7567 - SCIPreaderCanRead() and SCIPreaderCanWrite() in pub_reader.h, these return TRUE if the corresponding
7568 reader is capable to read or write, respectively
7569 - SCIPwriteOrigProblem(), e.g., SCIPwriteOrigProblem(scip, `orig.lp`, NULL, FALSE) prints the original
7570 problem in LP format in the file `orig.lp`
7571 - SCIPwriteTransProblem(), e.g., SCIPwriteTransProblem(scip, NULL, NULL, FALSE) displays the transformed problem in CIP format
7572
7573- Heuristics:
7574 - SCIPcutGenerationHeuristicCmir() in sepa_cmir.h
7575 - SCIPheurGetTimingmask() and SCIPheurSetTimingmask()
7576
7577- Sorting:
7578 - added some downwards-sorting methods
7579 - SCIPbsortInd()
7580 - SCIPsortedvecInsert...(), SCIPsortedvecInsertDown...(), SCIPsortedvecDelPos...(),
7581 SCIPsortedvecDelPosDown...(), SCIPsortedvecFind...() and SCIPsortedvecFindDown...() to manage sorted vectors or
7582 groups of vectors of various data types that are sorted w.r.t. the first vector
7583
7584### Command line interface
7585
7586- advanced reading and writing dialog in interactive shell
7587
7588### Interfaces to external software
7589
7590- Many changes in the SoPlex interface: The current one is tailored towards SoPlex 1.4 (aka 1.3.3). All SoPlex functions
7591 (where applicable) should now have an exception handling. The Bugfix for adding columns has been moved to SoPlex. One
7592 can use ROW representation. Reading/writing of a basis has been implemented.
7593
7594### Changed parameters
7595
7596- changed default frequency parameters for RINS, Local Branching, Crossover and Mutation heuristic This should not
7597 change the performance but happened just for consistency reasons
7598- changed parameter default values for the priority of presolver `dualfix` and `inttobinary`
7599- removed parameter `separating/cmir/maxtestdeltaroot`
7600- new value `l` for parameter `lp/pricing`, which is the new default
7601
7602### New parameters
7603
7604- `constraints/and/linearize` to enable linearization of all <and> constraints (in presolving),
7605- `constraints/and/initiallp` to turn on, off, or `auto` that the LP relaxation of the AND constraints are in the initial LP;
7606- `constraints/countsols/collect` to enable the storing of the solutions; default value FALSE;
7607- `constraints/indicator/addCoupling` to enable generation of relaxation
7608- `constraints/indicator/branchIndicators` to decide whether it is branched on indicator constraints in enforcing
7609- `constraints/indicator/genLogicor` to decide whether logicor constraints instead of cuts are generated
7610- `constraints/indicator/sepaAlternativeLP` to decide whether separation takes place using the alternative LP
7611- `constraints/linear/aggregatevariables` to search for aggregations in equations in the presolving step
7612- `constraints/linear/dualpresolving` to disable dual presolving step in the linear constraint handler; default value is TRUE
7613- `constraints/linear/simplifyinequalities` to enable a simplification step for inequalities; default value is set to FALSE = disabled
7614- `constraints/linear/upgrade/binpack` to enable or disable the linear upgrading process
7615- `constraints/linear/upgrade/eqknapsack` to enable or disable the linear upgrading process
7616- `constraints/linear/upgrade/invarknapsack` to enable or disable the linear upgrading process
7617- `constraints/linear/upgrade/knapsack` to enable or disable the linear upgrading process
7618- `constraints/linear/upgrade/logicor` to enable or disable the linear upgrading process
7619- `constraints/linear/upgrade/setppc` to enable or disable the linear upgrading process
7620- `constraints/linear/upgrade/varbound` to enable or disable the linear upgrading process
7621- `constraints/linear/presolusehashing` to use hashing comparison in cons_linear.c; default value is TRUE
7622- `constraints/logicor/presolusehashing` to use hashing comparison in cons_logicor.c; default value is TRUE
7623- `constraints/setppc/presolusehashing` to use hashing comparison in cons_setppc.c; default value is TRUE
7624- `constraints/SOS1/branchNonzeros` to decide whether SOS1 constraint with largest number of nonzero variables is picked for branching
7625- `constraints/SOS1/branchSOS` to enable or disable branching on SOS1 constraints
7626- `heuristics/feaspump/beforecuts` to allow the feaspump to be called before cut separation
7627- `heuristics/mutation/minimprove`
7628- `presol/donotmultaggr` which disables multiaggregation for all variables of the problem
7629- `separating/cmir/densityoffset` to allow for more c-MIR cuts on small models
7630- `separating/orthofunc` to choose function for scalar product computation in orthogonality test
7631
7632Testing
7633-------
7634
7635- updated mmm.{test,solu}, mittelmann.{test,solu}, miplib3.solu, miplib.solu, shortmiplib.test and added
7636 mittelmann_current.test, mittelmann_old.test
7637- added test scripts for testing counting (make testcount)
7638- removed tag make testpre (useless without corresponding scripts)
7639- added tag testcount (make testcount); this allows for testing counting problem
7640- replaced tcsh by bash and gawk by awk in all check scripts to achieve higher compatibility
7641
7642Build system
7643------------
7644
7645### Makefile
7646
7647- added `make/make.project` as default make include for external projects using SCIP
7648- added possibility to compile shared libraries in makefiles (and added `make/make.linux.x86.gnu.opt-shared`)
7649- replaced <string> by <cstring> in all C++-interfaces to get `strlen()` included (gcc-4.3 gave an error)
7650- Moved -rpath option for ld to linux-specific Makefiles.
7651- Re-activated readline library on darwin/ppc.
7652
7653- Flags:
7654 - added in all `make/make.*` `GMP_FLAGS` and `GMP_LDFLAGS`
7655 - new flag GMP with values (`auto`, `true and `false`); in case of `auto` the library gmp is linked if ZIMPL is
7656 included
7657 - adapted all makefiles of the examples accordingly
7658
7659- LP:
7660 - modified makefiles to accept ZIMPLOPT and LPSOPT flags (with values `opt` or `dbg` and default being `opt`), and
7661 removed `LPS=spxdbg` and `LPS=clpdbg`
7662 - added target spx132 for SoPlex version 1.3.2
7663
7664Fixed bugs
7665----------
7666
7667- fixed CTRL-C if NO_SIGACTION is set (e.g., for MinGW)
7668- added checks whether a plugin (handler) has already been included to avoid later complications e.g. with parameters.
7669- fixed bug with wrong `tightened` return value of some of the change bounds methods
7670- forced full propagation in presolving -> this fixes a bug that implied that variable locks became inconsistent
7671- replaced calls to perror() by SCIP error message using strerror(errno); this avoids problems with the error output
7672 stream
7673- fixed bug in method SCIPgetProbvarLinearSum()
7674- fixed bug with errors occurring in sub-MIPs. Search is only aborted in dbg mode, in opt mode a warning will be printed
7675- fixed bug in tclique-graph datastructure concerning insertion of edges into nonempty graph
7676- corrected bug in SCIPtreeBranchVar() (tree.c): several comparison functions needed a `feas`.
7677- fixed bug in SCIPtightenVarLb/Ub() in scip.c concering forcing a bound change (bound improvement is checked now)
7678- improved stage checking for bound computation
7679- fixed usage of command test for string comparison in check-scripts (now compatible with ubuntu)
7680- replaced sprintf and snprintf by SCIPsnprintf() fixed potential bug with overlong strings
7681- corrected bug in the case when soplex threw an exception in autopricing
7682- fixed bug in SCIPvarGetOrigvarSum() concerning the corner case the a negated variable has no parent variable in
7683 original problem
7684
7685- Aggregation:
7686 - avoid aggregation of implicit integers with fractional aggregation scalars
7687 - fixed bug in aggregateActiveIntVars(): If a < 0, multiply a*x + b*y == c by -1 (algo for finding initial solution does
7688 only work for a > 0).
7689 - avoiding aggregation that removes information about implicitly integer variables (removes bug)
7690 - fixed bug with exponential running times due to complicated recursive multi-aggregation
7691 - corrected bug in var.c occuring during applying boundchanges in varUpdateAggregationBounds method
7692
7693- Constraints:
7694 - fixed bug that a missing CONSTRANS in constraint handler leads to `NULL` pointer as constraint data for the copied
7695 constraints instead of pointer copies of the consdata (as explained in the constraint handler `HowTo`)
7696 - fixed bugs in second part of consdataTightenCoefs(): Removed min/maxleftactisinfinity (definition was not correct),
7697 fixed calculation of min/maxleftactivity and removed asserts concerning whether all redundant vars were deleted (led
7698 to different behavior in debug and opt mod).
7699 - fixed typo in documentation: default value for `dynamic` parameter is FALSE for all constraint handlers!
7700 - fixed bug in preprocessing of SOS2 constraints (cons_sos2.c)
7701 - fixed bug in cons_countsols.c concerning variable locking
7702 - fixed bug in cons_varbounds.c, concerning SCIPaddVarVlb() and SCIPaddVarVub()
7703 - fixed bug in applyFixings() in cons_varbound.c concerning tightening the bound of a variable left in a redundant
7704 constraint (bound change is forced now)
7705
7706- Heuristics:
7707 - fixed bug with useless objective cutoff in LNS heuristics
7708 - removed bug for values greater than (-)infinity, heur_shifting.c, heur_intshifting.c, heur_rounding.c, heur_oneopt.c
7709 - fixed bug with errors occurring in heuristic LPs. In opt mode a warning will be printed, abort in dbg mode
7710
7711- Linear Constraints:
7712 - fixed bug with wrong update of activities in linear constraints after global upper bound changes
7713 - fixed bug in preprocessConstraintPairs() in cons_linear.c concerning updating the flags of the constraint that stayes
7714 in the problem (nonredundant information were lost before)
7715 - fixed bug in cons_linear.c caused by comparing two infinity values during checking of using variable as slackvariable
7716 - removed bug for rhs/lhs greater than (-)infinity, cons_linear.c
7717 - removed bug caused by hashcomparison for non-sorted constraints, cons_linear.c
7718 - fixed bugs with wrong presolving due to cancellation in (res-)activities in cons_linear.c
7719 - removed BOUNDSCALETOL adjustment in cons_linear.c. This fixes bug with slightly infeasible variable fixings in
7720 presolving; reliable resactivities should make the BOUNDSCALETOL relaxation redundant.
7721 - removed `epsilontic` bug in cons_linear.c due to adjusting left/right hand side in applyfixing
7722 - fixed bug with multi-aggregated variables in cons_logicor: instead of fixing them, a linear constraint will be created
7723 - corrected bug in cons_linear.c:applyFixings() [if variable was fixed to infinity the rhs/lhs were wrong]
7724 - fixed bugs in pairwise presolving of cons_linear.c concerning deletion of upgraded constraints and inconsistent update
7725 of nchgsides in case of coefsequal and coefsnegated
7726 - fixed false assert and corrected a bug caused by deleting a constraint on `firstchanged` position in pairwise
7727 presolving with hashing in cons_linear.c
7728
7729- LP:
7730 - fixed handling of unbounded variables with 0 objective in SCIPlpGetModifiedPseudo[Proved]Objval() (lp.c)
7731 - fixed bug with uncatched LPSOLSTAT after hitting a time or iteration limit
7732 - corrected bug in SCIPlpGetState() if the LP is empty
7733 - fixed bug in SCIPlpSolveAndEval(): added extra simplex step if objlimit reached, fastmip and pricers enabled in order
7734 to get dual solution for pricing.
7735 - weakened two too strong asserts in lp.c concerning the LP result OBJLIMIT
7736 - fixed bug in SCIPlpSolveAndEval(): allow more than one extra simplex step for getting an objlimit exceeding solution
7737 with fastmip
7738
7739- Memory:
7740 - corrected invalid memory access in tcliqueIsEdge: added check whether node1 has no neighbors (tclique_graph.c)
7741 - removed memory leak detected with the help of coverity in dialog.c
7742 - fixed bug with memory reallocation in SCIPgetProbvarLinearSum()
7743 - tried to fix memory leak in dialog.c occuring from different versions of the readline/history libraries
7744 - removed possible memory leak in objdialog.cpp
7745
7746- Numerical:
7747 - fixed numerical issue in linear constraint propagation: need slightly more aggressive tightening such that probing
7748 does not choose a wrong value for fixing inside an epsilon interval
7749 - fixed numerical bug in dual presolving of linear constraint handler
7750 - avoid fixing variables to infinity in order to get rid of numerical inconsistencies in the original model
7751
7752- Objective:
7753 - added handling of the case of roundable variables with 0 objective in presol_dualfix.c
7754 - fixed bug with writing the MIP relaxation to a file concerning the objective function; in case the original objective
7755 function is requested, the transformed objective function gets re-transformed (scaling, offset)
7756 - fixed bug with wrong objective sense output for transformed problem. The transformed problem is always a minimization
7757 problem!
7758 - fixed bug with objective scaling after restart
7759
7760- Reading:
7761 - fixed bug with reading empty lines in TSP example
7762 - fixed bug with non-conformal parameter name in reader_ppm
7763 - fixed infinite loop in LP file reader if a line exceeds the character limit
7764 - fixed bug in reader_ppm while appending strings for output file
7765 - fixed some `SCIP_RETCODE` bugs in reader_fix.c, reader_sol.c, reader_sos.c and reader_zpl.c
7766 - fixed docu in type_reader.h
7767 - fixed bug with multi-aggregated variables which are de facto aggregated or fixed after flattening the aggregation tree
7768 - fixed bug with bound changes of variables in modifiable constraints during full dual presolving of linear conshdlr
7769 - increased compiler compatibility for C++ wrapper classed by adding extern `C` in obj*.cpp files and changing strlen
7770 calls to std::strlen
7771
7772- Separation:
7773 - corrected bug in priceAndCutLoop(): separation was aborted if domain reduction was applied
7774 - fixed bug in sepa_mir.c: size of testeddeltas-array was too small
7775 - corrected imlementation of SCIPlpiGetBasisInd() in lpi_clp.cpp (this fixes the bug that almost no Gomory cuts are
7776 found with Clp).
7777
7778- Sorting:
7779 - fixed bugs in sorttpl.c: fixed wrong arraysize in shellsort; in case an has at most one element, then no sorting is
7780 applied
7781 - fixed wrong if condition for function call in sorttpl.c
7782 - fixed obvious bug in linear constraint data sorting. Most part of the code assumed pure index sorting, but in fact, it
7783 was sorted by variable type as first criterion and index as second criterion.
7784
7785@page RN10 Release notes for SCIP 1.0
7786
7787@section RN100 SCIP 1.0.0
7788*************************
7789
7790Features
7791--------
7792
7793- SCIP now has a couple of specialized settings, all called scip_*.set
7794- SCIP is now compatible to the Exception branch of SoPlex
7795- if possible, objective function is scaled to make objective value integral with gcd 1
7796- slightly modified automatic constraint aging strategy
7797- new C templates disp_xxx.h and dialog_xxx.h and C++ wrapper classes objdisp.h and objdialog.h, respectively
7798- modified reader `sol`, st. files which where created via typing the order of commands `set log *.sol`,
7799 `disp sol var -`, `set log cplex.log` in Cplex can now be read
7800- new dummy LP interface `lpi_none.c`; useful for running SCIP without a LP solver
7801
7802- Presolver:
7803 - modified probing presolver to do multiple cycles if called in subsequent runs
7804 - changed sort algorithm in probing presolver
7805
7806- Node selection:
7807 - new node selection rule `estimate` (best estimate search)
7808 - new node selection rule `hybridestim`
7809
7810- Documentation:
7811 - the doxygen documentation now has HowTo's for all plugin types
7812 - the doxygen documentation now contains a FAQ
7813 - the documentation has now a TAB Modules; there you can find list of available constraint handles, presolvers,
7814 propagators, lpi interfaces, file readers and so on
7815
7816- Time:
7817 - time limit is now forwarded to lp solving algorithm
7818 - presolving, cut separation, primal heuristics and strong branching now better respect time limit
7819
7820- Heuristics:
7821 - best estimate search is now used in all large neighborhood search heuristics
7822 - new improvement heuristic `oneopt`
7823 - new heuristic `actconsdiving` following an idea of John Chinneck
7824
7825- Separation and Cuts:
7826 - modified cut selection code
7827 - cut conversion into linear constraints after a restart now works better
7828 - added flow cover separator
7829 - gomory cuts are now also separated for integral slack variables
7830 - less aggressive in Gomory cut separation
7831 - strong CG cuts are now also separated for integral slack variables
7832
7833Performance improvements
7834------------------------
7835
7836- greatly improved performance of LP file reader by replacing string copies with pointer copies
7837- removed performance bottleneck with non-bfs based node selectors and large leaf queues at the cost of a small memory
7838 overhead (2 ints per node in the leaf queue); this improves performance quite a bit on instances that take a large
7839 number of branching nodes
7840- improved performance of linear constraint propagation by delaying some floor/ceil calculations
7841- improved performance of clique cut separator
7842
7843Interface changes
7844-----------------
7845
7846### New and changed callbacks
7847
7848- new callback method SCIPdialogFree()
7849
7850### Deleted and changed API methods
7851
7852- slightly modified bound substitution heuristic in SCIPcalcMIR() and SCIPcalcStrongCG()
7853- slightly less conservative in numerics for SCIPmakeRowIntegral()
7854- linear and knapsack constraint handler may now deal with coefficients of value zero
7855- new parameter `maxbounddist` for SCIPincludeSepa() and constructor ObjSepa()
7856- new parameter `restart` for method SCIPfreeSolve()
7857- calling SCIPwriteLP() is now possible in Solved Stage
7858- SCIPwrite{LP,MIP} may no longer be called after solving, since the LP data structures may not be valid
7859- All functions SCIP<datatype>Param() got a new parameter `isadvanced`.
7860 This does not influence the performance of SCIP, but the position of the parameter in the settings menu.
7861 Hence, if you do not care about this, you can assign any value to it.
7862 You should add the corresponding flag to the SCIP<datatype>Param() calls in your own source code.
7863
7864- Version:
7865 - modified `SCIP_SUBVERSION` to be a number instead of a string (to be able to use `SCIP_SUBVERSION >= ...`)
7866 - SCIPsubversion() now returns an int instead of a const char*
7867
7868- Tree and Nodes:
7869 - new parameter `estimate` for SCIPcreateChild() giving an estimate for value of best feasible solution in the subtree to
7870 be created. One possibility is to use SCIPgetLocalOrigEstimate() for this value.
7871 - removed method SCIPnodeGetPriority()
7872 - removed parameter `lowestboundfirst` from SCIPincludeNodesel()
7873
7874- Branching:
7875 - removed parameter `branchdir` from SCIPbranchVar()
7876 - new parameters `leftchild`, `eqchild` and `downchild` for SCIPbranchVar()
7877 - SCIPgetVarStrongbranch() now also returns lperror == TRUE if the solving process should be stopped, e.g., because of a
7878 time limit
7879
7880- Variable tightening:
7881 - replaced methods SCIPvarGetClosestVlb() and SCIPvarGetClosestVub() from pub_var.h by new methods
7882 SCIPgetVarClosestVlb() and SCIPgetVarClosestVlb() in scip.h
7883 - new parameter `force` for SCIPtightenVarLb() and SCIPtightenVarUb()
7884
7885### New API functions
7886
7887- SCIPreadSol()
7888- SCIPwriteMIP()
7889- SCIPgetLocalOrigEstimate() and SCIPgetLocalTransEstimate()
7890- SCIPisStopped()
7891- SCIProwIsInGlobalCutpool()
7892- SCIPresetParams()
7893- SCIPgetVarRedcost()
7894- SCIPtightenVarLbGlobal() and SCIPtightenVarUbGlobal()
7895- SCIPsepaGetMaxbounddist()
7896- SCIPboundchgGetNewbound(), SCIPboundchgGetVar(), SCIPboundchgGetBoundchgtype(),
7897 SCIPboundchgGetBoundtype(), SCIPboundchgIsRedundant(), SCIPdomchgGetNBoundchgs(), SCIPdomchgGetBoundchg()
7898- SCIPnodeUpdateLowerboundLP()
7899- SCIPcalcNodeselPriority()
7900- SCIPnodeGetEstimate()
7901- SCIPnodeGetDomchg()
7902- SCIPgetRootNode() (in combination with SCIPcutoffNode(), this allows the immediate finishing of the optimization)
7903
7904### Command line interface
7905
7906- default dialog menu now includes the commands `set default` and `display parameters`
7907- added option to write node LP and MIP relaxations to LP file from interactive shell
7908
7909### Changed parameters
7910
7911- parameters are now separated into basic and advanced, the latter ones have been moved to extra submenus
7912- priority parameters are now restricted to be in [INT_MIN/4,INT_MAX/4] to avoid overflow errors in comparison methods
7913- increased priority of `estimate` node selector, such that this is the new default node selector
7914- changed meaning of parameter setting `nodeselection/childsel = l`; old meaning is now called `r`
7915- changed default value of `conflict/maxvarsfac` to 0.1
7916- changed default value of `conflict/useprop` to TRUE
7917- changed default value of `conflict/useinflp` to TRUE
7918- changed default value of `conflict/usepseudo` to TRUE
7919- changed default value of `conflict/maxlploops` to 2
7920- changed default value of `conflict/lpiterations` to 10
7921- changed default value of `conflict/interconss` to -1
7922- changed default value of `conflict/reconvlevels` to -1
7923- changed default value of `conflict/settlelocal` to FALSE
7924- changed default value of `constraints/linear/propfreq` to 1
7925- changed default values of `heuristics/∗diving/backtrack` to TRUE
7926- changed default value of `nodeselection/restartdfs/stdpriority` to 10000
7927- changed default value of `numerics/boundstreps` to 0.05 in order to avoid very long propagation loops on continuous variables
7928- changed default value of `presolving/restartfac` to 0.05
7929- changed default value of `presolving/restartminred` to 0.10
7930- changed default value of `separating/objparalfac` to 0.01 for performance reasons
7931- changed default value of global `separating/maxbounddist` to 1.0
7932- changed default value of `separating/objparalfac` to 0.0001
7933
7934### New parameters
7935
7936- `conflict/enable` to globally enable or disable conflict analysis
7937- `constraints/linear/maxcardbounddist` and `constraints/knapsack/maxcardbounddist`
7938- `heuristics/∗diving/backtrack` to activate 1-level backtracking for most of the diving heuristics
7939- `heuristics/feaspump/maxstallloops`
7940- `nodeselection/childsel` to control the child selection
7941- `presolving/immrestartfac`
7942- `separating/∗/maxbounddist` to have individual maxbounddist parameters per separator
7943- `separating/clique/backtrackfreq` to speed up clique cut separation in heuristic fashion
7944- `separating/redcost/continuous`
7945
7946Build system
7947------------
7948
7949### Makefile
7950
7951- added version numbers to library files (There will be a softlink generated in the lib/ and bin/ directories without
7952 version number that point to the latest compiled version.)
7953- added .exe extension to binaries of MinGW
7954- removed the `.static` extension associated to the LINK variable from the Makefile system (If you want to build
7955 makefiles for shared library generation, use the OPT variable. For example, you could create a makefile
7956 `make/make.linux.x86.gnu.opt-shared` and compile it with `make OPT=opt-shared`.)
7957
7958- Defaults and Options:
7959 - modified the default LP solver to be SoPlex instead of CPLEX
7960 - added `LPS=none` for compiling SCIP without a LP solver
7961 - made `ZIMPL=true` the default; if you do not want to include ZIMPL support, call `make ZIMPL=false`
7962
7963Fixed bugs
7964----------
7965
7966- fixed bug in rowScale() concerning deletion of almost zero coefficients
7967- weakened assert in primal.c in order to avoid numerical troubles
7968- fixed bug with too long variable names
7969- fixed bug with strange user descriptions of plugins
7970- changed position of some asserts to prevent segmentation faults
7971- SCIPgetAvgPseudocostCount() and SCIPgetAvgPseudocostCountCurrentRun() now return the average over all integer
7972 variables instead of all variables, since pseudo costs are not recorded for continuous variables
7973- fixed wrong sorting of plugins with priorities close to INT_MIN or INT_MAX
7974- replaced `line` by `read` in Makefile, since `line` is non-standard
7975- fixed bug with branching rules that produce only one child with no changes to the problem
7976- fixed bug that external relaxator is not reset appropriately for a new problem instance
7977- removed wrong assert in function paramWrite()
7978- fixed bug with uninitialized in check.awk
7979- fixed bug in ZIMPL file reader for multiple occurrences of a single variable in the objective function
7980- fixed bug with deleting variables from the transformed problem that are contained in the implication graph
7981- fixed bug in root reduced cost fixing propagator that leads to an empty domain for a variable as a proof of optimality
7982 of the current incumbent
7983- fixed bug with fractional coefficients of binary variables in cont --> impl int upgrading
7984
7985- Solution:
7986 - fixed bug with aggregated variables in debug solution test
7987 - now it is possible to add original solutions
7988 - fixed bugs with SCIPgetBestsol() returning `NULL` after a restart with user objective limit
7989 - fixed wrong status code in presence of user objective limit and a feasible solution that is not better than the limit
7990
7991- Bounds:
7992 - fixed bug with wrong bound changes of loose variables
7993 - changed wrong assert in SCIPnodeAddBoundinfer()
7994 - fixed bug in variable bounds search and insertion method
7995 - fixed bug regarding modifying bounds in original problem if negated original variables exist
7996 - fixed bug with multiple pending bound changes on some variable
7997
7998- Separator:
7999 - fixed bug in integer objective separator with restarts
8000 - fixed bug in integer objective separator with dynamic columns
8001
8002- Cuts:
8003 - fixed bug that cut age was not reset to zero for violated cuts
8004 - fixed bug in SCIPcutpoolAddNewRow() concerning update of minidx and maxidx of added row
8005 - fixed numerical bug in rowScaling of lp.c, which possibly cut off feasible solutions
8006 - significantly improved performance of c-MIR and Gomory cuts by caching closest VLB and VUB info
8007
8008- LP:
8009 - fixed numerical buf with slightly different LP optimum after resolving due to probing/diving
8010 - fixed bug in cmir and flowcover separator with variables which are currently not in the LP
8011 - fixed bug with LP size management in probing if column generation is used
8012 - fixed bug in LP file reader with row names identical to section keywords
8013 - fixed potential bugs due to errors in resolving the LP after diving or probing
8014 - fixed potential bugs in SCIPpriceLoop() and priceAndCutLoop(), st. now all LP solution stati are handled appropriately
8015 - fixed potential bug with non-existent LP in SCIPwrite{LP,MIP}
8016
8017- Constraint handler:
8018 - removed wrong assert in bounddisjunction constraint enforcement
8019 - fixed numerical bug in propagator of varbound constraint handler
8020 - fixed bug in variable bound constraint handler with changing bounds on multi-aggregated variables
8021 - fixed bug in linear constraint handler: only tight cuts are transformed into linear constraints after restart
8022 - fixed bug in bounddisjunction constraint handler with propagation of multi-aggregated variables
8023 - fixed bug with numerics in linear constraint handler due to non-representable `BOUNDSCALETOL`
8024 - fixed bug with almost integral multi-aggregation in dual presolve of linear constraint handler
8025 - fixed bug with numerics in update of min/maxactivity in linear constraint handler
8026
8027- Heuristics:
8028 - fixed bug in intshifting and oneopt heuristic with variables which are currently not in the LP
8029 - fixed bug with primal heuristics reducing the cutoff bound such that the current node is cut off
8030 - fixed bug in oneopt heuristic: must not be called on pseudo nodes if continuous variables are present
8031
8032@page RN09 Release notes for SCIP 0.9
8033
8034@section RN090 SCIP 0.9.0
8035*************************
8036
8037Features
8038--------
8039
8040- the EXITSOL callback of the plugins is now called before the LP and the global cut pool are freed
8041
8042- Primal Heuristics:
8043 - new primal heuristics `rens`, `mutation` and `veclendiving`
8044 - primal heuristics that run before the node is solved now know already whether the LP will be solved at the current
8045 node or not
8046
8047- Heuristics:
8048 - new heuristic `intshifting` (ID character `i`)
8049 - in the root node of the very first run, heuristics with timing `AFTERNODELPNODE`, `AFTERLPPLUNGE`, `AFTERPSEUDONODE`, and
8050 `AFTERPSEUDOPLUNGE` are now called before the enforcement of the constraint handlers, in particular before the branching
8051 rules; in this way, the branching rule can already benefit from a tighter primal bound
8052 - if a heuristic found a better solution after the LP loop (and in particular the `AFTERNODE` heuristics in the root node
8053 of the very first run, see above), domain propagation and LP solving is triggered again; this allows for additional
8054 reduced cost tightening and other dual propagations
8055 - slightly modified `crossover` and `rins` heuristics
8056 - improved performance of intdiving heuristic
8057 - improved heuristic `octane` and `shifting`
8058 - slightly modified rens and localbranching heuristics
8059 - modified guided diving heuristic such that it equals the original version of the heuristic (i.e., round in direction of the
8060 current incumbent solution instead of the average of all primal feasible solutions)
8061 - ID character for intdiving heuristic is now `I`
8062
8063- Separation and Cuts:
8064 - c-MIR cuts try now to scale the cut to integral values; however, cuts are still generated if this fails
8065 - hard-coded relative objective gain to consider a separation loop to be stalling is now changed from 1e-3 to 1e-4,
8066 which means that separation is not aborted as early as before
8067 - modified c-MIR cut separator to more closely resemble the original version of Marchand and Wolsey
8068
8069- Constraint:
8070 - possibility of SAT-like restarts after a number of conflict constraints have been found
8071 - improved presolving of and, or and xor constraints
8072 - implemented additional dual presolving in linear constraint handler
8073 - slightly modified presolving of varbound constraint handler
8074
8075Interface changes
8076-----------------
8077
8078### New and changed callbacks
8079
8080- new parameter `solinfeasible` for constraint handler callback methods `ENFOLP` and `ENFOPS`
8081- replaced callback parameter `inlploop` and `inplunging` by `heurtiming` in `SCIP_DECL_HEUREXEC`
8082- slightly changed the meaning of the result codes returned by external relaxators: if they modify the LP or tighten
8083 bounds of variables, they are not automatically be called again (it is assumed that they already made use of these
8084 changes). They are only called again, if they returned `SCIP_SUSPENDED` or if some other plugin modified the LP.
8085
8086### Deleted and changed API methods
8087
8088- new parameter `escapecommand` for SCIPdialoghdlrAddHistory()
8089- removed method SCIPgetVarData(); use SCIPvarGetData() from pub_var.h instead
8090- new calls SCIPgetLPBInvCol() and SCIPgetLPBInvACol() to access the basis inverse and simplex tableau columnwise
8091- new parameter `ndomredsfound` of SCIPpropagateProbing()
8092- new parameters `fixintegralrhs`, `maxfrac`, `mksetcoefs` and `fracnotinrange` in SCIPcalcMIR()
8093- modified SCIPfixVar() such that in problem creation stage it will change the bounds as requested even if the fixing
8094 value is outside of the current bounds
8095- replaced parameters `pseudonodes`, `duringplunging`, `duringlploop` and `afternode` by `timingmask` in
8096 SCIPincludeHeur() and constructor of ObjHeur() class use the following table to translate old settings into the new
8097 timingmask:
8098
8099| PSEUDONODES | DURINGPLUNGING | DURINGLPLOOP | AFTERNODE | timingmask |
8100|-------------|----------------|--------------|-----------|---------------------------------------------------------------|
8101| FALSE | FALSE | FALSE | FALSE | SCIP_HEURTIMING_BEFORENODE |
8102| TRUE | FALSE | FALSE | FALSE | SCIP_HEURTIMING_BEFORENODE |
8103| FALSE | TRUE | FALSE | FALSE | SCIP_HEURTIMING_BEFORENODE |
8104| TRUE | TRUE | FALSE | FALSE | SCIP_HEURTIMING_BEFORENODE |
8105| FALSE | FALSE | TRUE | FALSE | SCIP_HEURTIMING_BEFORENODE \| SCIP_HEURTIMING_DURINGLPLOOP |
8106| TRUE | FALSE | TRUE | FALSE | SCIP_HEURTIMING_BEFORENODE \| SCIP_HEURTIMING_DURINGLPLOOP |
8107| FALSE | TRUE | TRUE | FALSE | SCIP_HEURTIMING_BEFORENODE \| SCIP_HEURTIMING_DURINGLPLOOP |
8108| TRUE | TRUE | TRUE | FALSE | SCIP_HEURTIMING_BEFORENODE \| SCIP_HEURTIMING_DURINGLPLOOP |
8109| FALSE | FALSE | FALSE | TRUE | SCIP_HEURTIMING_AFTERLPPLUNGE |
8110| TRUE | FALSE | FALSE | TRUE | SCIP_HEURTIMING_AFTERPLUNGE |
8111| FALSE | TRUE | FALSE | TRUE | SCIP_HEURTIMING_AFTERLPNODE |
8112| TRUE | TRUE | FALSE | TRUE | SCIP_HEURTIMING_AFTERNODE |
8113| FALSE | FALSE | TRUE | TRUE | SCIP_HEURTIMING_AFTERLPPLUNGE \| SCIP_HEURTIMING_DURINGLPLOOP |
8114| TRUE | FALSE | TRUE | TRUE | SCIP_HEURTIMING_AFTERPLUNGE \| SCIP_HEURTIMING_DURINGLPLOOP |
8115| FALSE | TRUE | TRUE | TRUE | SCIP_HEURTIMING_AFTERLPNODE \| SCIP_HEURTIMING_DURINGLPLOOP |
8116| TRUE | TRUE | TRUE | TRUE | SCIP_HEURTIMING_AFTERNODE \| SCIP_HEURTIMING_DURINGLPLOOP |
8117
8118- Constraints:
8119 - renamed all occurences of `removeable` by the correct English word `removable`: SCIPconsIsRemovable(),
8120 SCIPsetConsRemovable(), SCIPvarIsRemovable(), SCIPcolIsRemovable(), SCIProwIsRemovable()
8121 - new parameter `sticktonode` in SCIPcreateCons(), SCIPcreateConsAnd(), SCIPcreateConsBounddisjunction(),
8122 SCIPcreateConsKnapsack(), SCIPcreateConsLinear(), SCIPcreateConsLogicor(), SCIPcreateConsOr(),
8123 SCIPcreateConsVarbound(), SCIPcreateConsXor(), SCIPcreateConsSetpart(), SCIPcreateConsSetpack(),
8124 SCIPcreateConsSetcover(): usually, you should set this to FALSE; if you want to add constraints as node markers with
8125 node data and, e.g., use the `activate` and `deactivate` callbacks to get informed about the activation and
8126 deactivation of the node, you should set this flag to TRUE in order to make sure, that the constraint will always be
8127 associated to the node and not moved to a more global node if this would be possible
8128 - slightly changed semantics of SCIPaddConsNode() and SCIPaddConsLocal(), such that a constraint which is added to the
8129 root node now enters the global problem (and is still existing after a restart)
8130
8131### New API functions
8132
8133- SCIPgetVerbLevel()
8134- SCIPescapeString()
8135- SCIPgetGlobalCutpool(), SCIPgetPoolCuts(), SCIPcutpoolGetCuts(), SCIPcutGetRow() and SCIPcutGetAge()
8136- SCIPconsGetNLocksPos() and SCIPconsGetNLocksNeg()
8137
8138### Command line interface
8139
8140- command shell now understands escape characters `\``,`'` and `\` which makes it possible to read in files with spaces in the
8141 name
8142
8143### Interfaces to external software
8144
8145- updated XPress interface to XPress-MP 17 (contributed by Michael Perregaard)
8146
8147### Changed parameters
8148
8149- changed default value of `heuristics/octane/usediffray` to FALSE
8150- removed parameter `heuristics/octane/usediffbwray`
8151- renamed parameter `heuristics/octane/useavgray` to `heuristics/octane/useavgnbray`
8152- changed default value of `heuristics/rens/binarybounds` to TRUE
8153- changed default value of `heuristics/octane/freq` to -1 in order to deactivate Octane
8154- parameter `heuristics/feaspump/maxsols` is now strict, i.e., if n solutions were already found, the feasibility pump
8155 starts to work only if `maxsols <= n`, instead of `maxsols < n`
8156
8157### New parameters
8158
8159- `conflict/restartnum` and `conflict/restartfac`
8160- `heuristics/octane/useavgray`
8161- `heuristics/octane/useavgwgtray`
8162- `limits/absgap` to define an absolute gap limit
8163- `separating/cmir/aggrtol`
8164- `separating/cmir/densityscore`
8165- `separating/cmir/fixintegralrhs`
8166- `separating/maxruns`
8167- `presolving/restartminred` which forbids another restart if the last one was not successful enough
8168- `propagating/abortoncutoff`
8169- `reading/zplreader/changedir` to control behavior of path switching of ZIMPL file reader
8170- `reading/zplreader/parameters` to pass additional parameters to ZIMPL
8171
8172Build system
8173------------
8174
8175### Makefile
8176
8177- added ncurses to the readline entries in the `make/make.*` files
8178- added quotes to sed expressions in Makefile (needed under Windows)
8179- modified makefiles for Windows/Intel
8180- added automatic query script in the Makefile for soft-link names
8181
8182Fixed bugs
8183----------
8184
8185- fixed bug with string pointer copy instead of string content duplication in constructors of C++ wrapper classes
8186- fixed bug in CPLEX interface with basis access methods that dualopt has to be called for more error status codes
8187- fixed bug with inserting two variable bounds of the same type on the same variable with the same bounding variable but
8188 with different sign of coefficient (e.g., `x <= 10*z + 5` and `x <= -5*z + 10`); in previous version, one of the two was
8189 removed, although both have a useful meaning; now, we keep both and detect a stronger global bound in the implication graph presolving
8190- objective function is now also checked for integrality after problem transformation (fixed a bug that a solution which
8191 was generated between transformation and presolving for an integral objective function did not reduce the cutoff bound by one)
8192- fixed a bug with cmir cut efficacy calculation (however, on my first tests, the performance reduced slightly!)
8193- fixed bug that SCIPvarGetAvgSol() always returned the upper bound (affected guided diving heuristic)
8194- fixed bug in RENS, RINS, Local Branching, Crossover and Mutation heuristics with wrong variable-subvariable assignments
8195- fixed bug in infeasible/bound-exceeding LP conflict analysis if the bounds were relaxed in diving (happens in intshifting heuristic)
8196
8197- Separation:
8198 - fixed bug with adding constraints with `INITIAL=true` and separating them afterwards, which lead to a second addition of
8199 the constraint's relaxation in the child node
8200 - separation LPs are now immediately resolved after a bound change was generated by a cut separator; before, the
8201 separation round was prematurely aborted, which means that a separation round limit was sometimes reached very quickly
8202 and some of the separators were not even called a single time
8203
8204- Cmir Cut Separator:
8205 - too large deltas are now also rejected in c-MIR cut separation
8206 - fixed bug in cmir cut separator, that 8*delta was not tried
8207 - fixed bug in cmir cut separator with wrong sign of slack in row score function
8208 - fixed bug in cmir cut separator with weights fixed to zero, thus making the current aggregation invalid
8209 - fixed bug in cmir cut separator with wrong calculation of cut efficacies
8210
8211@page RN08 Release notes for SCIP 0.8
8212
8213@section RN082 SCIP 0.8.2
8214*************************
8215
8216Features
8217--------
8218
8219- additional flag `delay` for pricers
8220- new propagator `rootredcost` which applies reduced cost fixing at the root node whenever a best new primal solution was found
8221- new separator `redcost` which replaces the internal reduced cost strengthening
8222
8223- LP:
8224 - extensions to the LP are kept even if the LP is not solved at the current node; however, if the LP turned out to be
8225 numerically instable, the extensions of the current node are still discarded
8226 - added removal of bound-redundant rows from the LP during root node LP solving loop
8227 - new display column `lpobj`
8228
8229- Constraints:
8230 - slightly changed priorities of constraint handlers
8231 - now, conflict constraints are also created if they were generated in strong branching or diving with insertion depth
8232 equal to the current depth
8233 - new constraint handler `bounddisjunction`
8234
8235- Readers:
8236 - renamed `sol` file reader to `fix` file reader (reads partial solution files and fixes variables to the given values)
8237 - added `sol` file reader which reads complete solution files and adds the solutions to the solution pool
8238 - LP and MPS file readers are now able to parse lazy constraints and user cuts sections
8239
8240- Presolver:
8241 - knapsack presolver now generates cliques in the clique table (this essentially solves `neos1.mps`)
8242 - new presolver `inttobinary`
8243
8244- Heuristics:
8245 - new primal heuristic `shifting`
8246 - diving heuristics abort earlier (did not come back in reasonable time on `fast0507`)
8247
8248Interface changes
8249-----------------
8250
8251- new solution status code `SCIP_STATUS_STALLNODELIMIT`
8252
8253### New and changed callbacks
8254
8255- slightly modified semantics of the `CONSINITLP` callback in the constraint handlers
8256
8257### Deleted and changed API methods
8258
8259- methods SCIPisLbBetter() and SCIPisUbBetter() have an additional parameter and slightly different meaning (they now
8260 compare the bound improvement *relatively* to the width of the domain and the bound itself)
8261- SCIPgetNSols() now returns an int instead of `SCIP_Longint`
8262- method SCIPreadProb() does not call SCIPfreeTransform() anymore; file readers that want to extend the existing problem
8263 must now call SCIPfreeTransform() themselves before modifying the original problem
8264- method SCIPgetBinvarRepresentative() can now also be called in problem creation stage
8265- additional parameter `maxpricerounds` in method SCIPsolveProbingLPWithPricing()
8266- changed name of method SCIPpresolGetNVarTypes() to SCIPpresolGetNChgVarTypes()
8267- method SCIPsplitFilenames() now treats both versions of slashes, `/` and `\`, as directory delimiters (under MinGW and
8268 CygWin, both are valid; so, we cannot treat file names anymore where the other slash is used as a regular character)
8269
8270- Constraints:
8271 - marking a constraint to be `initial` now means in addition, that if the constraint is added to a local node it will
8272 enter the LP at the time the node is first processed, even if parameters forbid separation at this node
8273 - changed name of method SCIPconshdlrGetNVarTypes() to SCIPconshdlrGetNChgVarTypes()
8274
8275- Conflicts:
8276 - method SCIPgetNConflictClausesFound() renamed to SCIPgetNConflictConssFound()
8277 - method SCIPgetNConflictClausesFoundNode() renamed to SCIPgetNConflictConssFoundNode()
8278 - method SCIPgetNConflictClausesApplied() renamed to SCIPgetNConflictConssApplied()
8279
8280### New API functions
8281
8282- SCIPsolveProbingLPWithPricing()
8283- SCIPchgVarLbRoot() and SCIPchgVarUbRoot()
8284- SCIPinRepropagation()
8285- SCIPaddDialogInputLine() and SCIPaddDialogHistoryLine()
8286- SCIPtransformProb() to create the transformed problem; enables the user, e.g., to add primal solutions before the presolving begins
8287- SCIPcreateSolCopy()
8288- SCIPareSolsEqual()
8289
8290- Getters:
8291 - SCIPgetRowKnapsack(), SCIPgetRowLinear(), SCIPgetRowLogicor(), SCIPgetRowSetppc(), and
8292 SCIPgetRowVarbound() for obtaining the linear relaxation of a corresponding constraint
8293 - SCIPgetLhsVarbound(), SCIPgetRhsVarbound(), SCIPgetVarVarbound(), SCIPgetVbdvarVarbound(), and
8294 SCIPgetVbdcoefVarbound()
8295 - SCIPgetLPRootObjval(), SCIPgetLPRootColumnObjval() and SCIPgetLPRootLooseObjval()
8296 - SCIPcolGetMinPrimsol() and SCIPcolGetMaxPrimsol()
8297 - SCIPgetFocusDepth()
8298
8299- Score:
8300 - SCIPgetAvgPseudocostScore()
8301 - SCIPgetAvgPseudocostScoreCurrentRun()
8302 - SCIPgetAvgConflictScore()
8303 - SCIPgetAvgConflictScoreCurrentRun()
8304 - SCIPgetAvgInferenceScore()
8305 - SCIPgetAvgInferenceScoreCurrentRun()
8306 - SCIPgetAvgCutoffScore()
8307 - SCIPgetAvgCutoffScoreCurrentRun()
8308
8309- Reduced Cost:
8310 - SCIPgetColRedcost()
8311 - SCIPvarGetRootRedcost()
8312
8313- Variables:
8314 - SCIPgetNVarsAnd() and SCIPgetVarsAnd()
8315 - SCIPgetWeightsKnapsack(), SCIPgetNVarsKnapsack(), SCIPgetVarsKnapsack() and SCIPgetWeightsKnapsack()
8316 - SCIPgetNVarsLinear(), SCIPgetVarsLinear() and SCIPgetValsLinear()
8317 - SCIPgetNVarsOr() and SCIPgetVarsOr()
8318 - SCIPgetNVarsXor() and SCIPgetVarsXor()
8319
8320### Command line interface
8321
8322- command line syntax changed to support batch modus without piping stdin with `<` or `|` operators
8323- advanced command line syntax:
8324 - `-l <logfile> `: copy output into log file
8325 - `-q `: suppress screen messages
8326 - `-s <settings> `: load parameter settings (.set) file
8327 - `-f <problem> `: load and solve problem file
8328 - `-b <batchfile>`: load and execute dialog command batch file (can be used multiple times)
8329 - `-c <command> `: execute single line of dialog commands (can be used multiple times)
8330
8331### Interfaces to external software
8332
8333### Changed parameters
8334
8335- removed parameter `propagating/redcostfreq`, because reduced cost strengthening is now an external separator plugin
8336- removed parameter `conflict/maxunfixed`
8337- parameter `conflict/maxclauses` renamed to `conflict/maxconss`
8338- parameter `conflict/interclauses` renamed to `conflict/interconss`
8339- parameter `conflict/reconvclauses` replaced by `conflict/reconvlevels`
8340- parameter `conflict/uselp` replaced by `conflict/useinflp` and `conflict/useboundlp`
8341- changed default value of `constraints/obsoleteage` to -1
8342- changed default value of `branching/relpscost/conflictweight` to 0.01
8343- changed default value of `branching/relpscost/inferenceweight` to 0.0001
8344- changed default value of `branching/relpscost/cutoffweight` to 0.0001
8345- in bfs node selector, parameter `minplungedepth` is now stronger than `maxplungedepth` if they conflict
8346
8347### New parameters
8348
8349- `constraints/linear/separateall`
8350- `conflict/lpiterations`
8351- `conflict/keepreprop`
8352- `branching/relpscost/conflictweight`, `branching/relpscost/inferenceweight`,
8353 `branching/relpscost/cutoffweight` and `branching/relpscost/pscostweight`
8354- `conflict/settlelocal`
8355- `conflict/depthscorefac`
8356- `limits/stallnodes`
8357
8358Build system
8359------------
8360
8361### Makefile
8362
8363- removed ncurses and pthread libraries from the Makefile; pthread is now only linked if CPLEX is used
8364
8365Fixed bugs
8366----------
8367
8368- fixed numerical bug in SCIPrealToRational() [thanks to Anders Schack-Nielsen]
8369- fixed bug in crossover heuristic with negative timelimit
8370- removed bug in conflict analysis with wrong redundancy check
8371- fixed bug that unexpected end of stdin (Ctrl-D or piped-in file without `quit` command) gives a segmentation fault
8372- fixed bug with inconsistent data structures after a global bound was changed at a local subproblem and the local
8373 bounds are not contained anymore in the new global bounds
8374- fixed dependency generation in example Makefiles
8375
8376- Knapsack:
8377 - fixed bug in knapsack presolving with redundancy check after applyFixings() [thanks to Anders Schack-Nielsen]
8378 - fixed bug in knapsack separator with empty initial covers
8379 - fixed bug in knapsack constraint disaggregation that may lead to acceptance of infeasible solutions
8380 - fixed bug in knapsack constraint handler where a modifiable constraint may be declared redundant
8381
8382- LP:
8383 - fixed bug with missing LP size updates after pricing or cut separation in probing [thanks to Marc Nuenkesser]
8384 - fixed bug in CPLEX interface with getting basis information after the LP was modified and restored
8385 - fixed bug with updating LP size in probing
8386 - fixed bug that SCIPgetLPSolstat() returns a valid status code even if the LP was not yet constructed for the current node
8387
8388- Variables:
8389 - fixed bug with invalid lazy updates after a restart where the LP is not solved again (e.g., due to all variables being fixed)
8390 - fixed bugs resulting from inactive general integer variables being member of the variable bounds array of a variable
8391 - fixed bug in updatePseudocost() with wrong lpgain distribution on multiple branching variables [thanks to Anders Schack-Nielsen]
8392 - fixed bug in objconshdlr.h where member variable scip_maxprerounds_ was declared as an `SCIP_Bool` instead of an int
8393 - branching on nearly-integral variables is now avoided in relpscost branching, which lead to a numerical assertion
8394
8395- Implication:
8396 - fixed bug with adding implications that fix the implication variable to the opposite value (due to the bug, it was
8397 returned that the whole problem is infeasible)
8398 - removed wrong assert in varRemoveImplicsVbs()
8399
8400- Cliques:
8401 - fixed bug in SCIPcliqueSearchVar() [thanks to Anders Schack-Nielsen]
8402 - fixed bug in SCIPcliqueAddVar() [thanks to Anders Schack-Nielsen]
8403
8404- Readers:
8405 - fixed bug in MPS file reader with `OBJSENSE`
8406 - fixed bug in LP reader with potentially uninitialized pointers [thanks to Martin Mueller]
8407
8408- Constraints:
8409 - it is now possible to branch on constraints without the risk of going into an infinite loop, because constraints marked as `initial`
8410 will be put to the LP relaxation (of the child nodes) even if separation is prohibited by the parameter settings
8411 - fixed bug that locally valid varbound constraints produce VLB/VUB entries [thanks to Anders Schack-Nielsen]
8412
8413@section RN081 SCIP 0.8.1
8414*************************
8415
8416Features
8417--------
8418
8419- improved performance of the priority queue in conflict analysis
8420- slightly modified restartdfs node selector
8421
8422- Presolving:
8423 - new presolver `implics` to find bound changes and aggregations out of the implication graph
8424 - modified probing order in probing presolver
8425
8426- Constraints:
8427 - changed handling of added constraints in separation calls
8428 - modified bookkeeping of locally added and disabled constraints such that the order of enabling and disabling constraints stays the same
8429 - logic or constraint handler now adds implications on clauses with 2 literals to the implication graph
8430 - and/or constraint handlers now add implications to the implication graph
8431 - xor constraint handler now uses stronger LP relaxation without auxiliary variable for xor constraint with 2 operands
8432
8433- Heuristics:
8434 - added preliminary version of `intdiving` heuristic (disabled in default settings)
8435 - added crossover heuristic
8436
8437- Readers:
8438 - LP file reader now accepts the keyword `Integer` for defining the start of the integer variables section
8439 - new file reader for (partial) solutions
8440
8441Examples and applications
8442-------------------------
8443
8444- added two small pricer examples (for C and C++)
8445- updated example code (s.t. it compiles again)
8446
8447Interface changes
8448-----------------
8449
8450### New and changed callbacks
8451
8452- callback method `CONSSEPA` of constraint handler was split into two methods `CONSSEPALP` and `CONSSEPASOL`
8453- callback method `SEPAEXEC` of separator was split into two methods `SEPAEXECLP` and `SEPAEXECSOL`
8454
8455### Deleted and changed API methods
8456
8457- replaced method SCIPsepaWasDelayed() by SCIPsepaWasLPDelayed() and SCIPsepaWasSolDelayed()
8458- additional parameter `sol` for methods SCIPaddCut(), SCIPgetCutEfficacy() and SCIPisCutEfficacious()
8459- additional parameter `sol` for method SCIPseparateKnapsackCover()
8460- primal solutions may now contain values marked to be unknown (value is `SCIP_UNKNOWN`); unknown values don't contribute
8461 to the objective value of the solution; an unknown solution value should be treated as an arbitrary value in the
8462 variable's bounds, e.g., in the calculation of the feasibility of a constraint, a value inside the variable's bounds
8463 should be selected that makes the constraint as feasible as possible
8464- new parameter `printzeros` for methods SCIPprintSol(), SCIPprintTransSol(), SCIPprintBestSol() and SCIPprintBestTransSol()
8465
8466- Constraints:
8467 - replaced method SCIPconshdlrWasSeparationDelayed() by two methods SCIPconshdlrWasLPSeparationDelayed() and
8468 SCIPconshdlrWasSolSeparationDelayed()
8469 - renamed method SCIPgetNGlobalConss() to SCIPgetNConss()
8470
8471### New API functions
8472
8473- SCIPgetCuts()
8474- SCIPgetVarConflictScore() and SCIPgetVarConflictScoreCurrentRun()
8475- SCIPvarSetData()
8476- SCIPcreateUnknownSol()
8477- SCIPgetNConflictClausesFoundNode()
8478- SCIPvarSetDelorigData(), SCIPvarSetTransData() and SCIPvarSetDeltransData()
8479- SCIPvarHasBinaryImplic()
8480- SCIPgetFixedVars() and SCIPgetNFixedVars()
8481- SCIPgetConss(), SCIPgetNOrigConss() and SCIPgetOrigConss()
8482- SCIPsepaGetNConssFound() and SCIPsepaGetNDomredsFound()
8483- SCIPconstructLP() to force constructing the LP of the current node
8484- SCIPisLPConstructed()
8485
8486### Command line interface
8487
8488- added `write statistics` command to default user dialogs
8489
8490### Changed parameters
8491
8492- modified meaning of parameter `presolving/probing/maxtotaluseless`
8493- heuristics with `freq = 0` and `freqofs > 0` are now called in depth level freqofs instead of being called in the root
8494 node
8495- added some parameters in local branching and RINS heuristic
8496- new parameter values `p`rimal simplex and `d`ual simplex in `lp/initalgorithm` and `lp/resolvealgorithm`
8497
8498### New parameters
8499
8500- `branching/inference/conflictweight`
8501
8502Build system
8503------------
8504
8505### Makefile
8506
8507- included version number in binary file name
8508- tried to make the code Windows compatible
8509
8510Fixed bugs
8511----------
8512
8513- also removed history_length, if `NO_REMOVE_HISTORY` is defined to support older versions of the readline library
8514- hopefully fixed bug with wrong path slash `/` under Windows
8515- fixed bug with aggregating fixed variables
8516
8517- Implications:
8518 - fixed bug in transitive implication addition
8519 - fixed wrong assert with implications that imply a fixed variable
8520 - removed bug in implication addition
8521
8522- Readers:
8523 - fixed bug in ZIMPL model reader with wrong chdir, if .zpl file is in current directory
8524 - fixed bug in LP file reader with signed values without space between sign and value (e.g. `+2x` instead of `+ 2x`)
8525 - fixed various bugs in LP file reader
8526 - fixed bug in LP file reader with explicit zero coefficients
8527
8528- Numerics:
8529 - fixed numerics in probing and linear constraint handler (rentacar was detected to be infeasible in presolving)
8530 - fixed numerics in check method of linear constraint handler
8531 - fixed bug with numerical error in LP resolve after probing or diving
8532
8533- Heuristics:
8534 - fixed bug with calling heuristics in depths smaller than their frequency offset
8535 - fixed bugs in local branching and RINS heuristic
8536
8537Known bugs
8538----------
8539
8540- if one uses column generation and restarts, a solution that contains variables that are only present in the
8541 transformed problem (i.e., variables that were generated by a pricer) is not pulled back into the original space
8542 correctly, since the priced variables have no original counterpart
8543
8544@section RN080 SCIP 0.8.0
8545*************************
8546
8547Features
8548--------
8549
8550- adding variable bounds automatically adds the corresponding implication
8551- changed restart dfs nodeselector to sort leaves by node number instead of node depth to aviod jumping around in the
8552 search tree after a restart was applied and the current dive ended due to infeasibility
8553- new Message Handler plugin
8554- added file reader for LP format
8555- introduced subversion string
8556- replaced all abort() calls by SCIPABORT(); this is defined in def.h to be `assert(FALSE)`
8557- added possibility to disable certain features by using `make USRFLAGS=-DNO_REMOVE_HISTORY`, `make
8558 USRFLAGS=-DNO_SIGACTION`, `make USRFLAGS=-DNO_RAND_R`, or `make USRFLAGS=-DNO_STRTOK_R`
8559- improved preprocessing abort criteria
8560- added zlib support
8561
8562- Conflict Analysis:
8563 - conflict clauses are now collected in a conflict store, redundant clauses are eliminated and only the best `conflict/maxclauses`
8564 clauses are added permanently to the problem; the remaining clauses are only added temporarily, if they can be used for repropagation
8565 - modified the influence of the depth level in conflict analysis
8566 - slightly changed LP resolving loop in conflict analysis
8567 - if CPLEX returns that the LP exceeds the bound and if no additional LP solves are allowed in conflict analysis, we
8568 have to perform one additional simplex iteration to get the dual solution that actually violates the objective limit
8569
8570- Constraints:
8571 - reactivated multiaggregation in cons_linear.c on binary variables again (possible due to bug fix below)
8572 - improved preprocessing of variable bounds constraints
8573 - linear constraint handler now catches events of variables after the problem was completely transformed in order to
8574 avoid the whole bunch of `LOCKSCHANGED` events that are generated at problem transformation stage
8575 - added redundancy detection for pairs of constraints in setppc constraint handler
8576
8577- Presolving and Cliques:
8578 - changed linear constraint presolving s.t. redundant sides are not removed if constraint is an equality
8579 - new event type `SCIP_EVENTTYPE_PRESOLVEROUND`
8580 - modified probing presolver to not add implications that are already included in the implication graph and clique table
8581 - incorporated clique and implication information in knapsack constraint presolving
8582 - removed transitive clique generation, because this produces way too many cliques
8583
8584- Heuristics:
8585 - diving heuristics now apply propagation at each step
8586 - removed `objfeaspump` heuristic, because the functionality can be achieved by using the `feaspump` heuristic
8587 - diving heuristics are now applying propagation after each bound change
8588 - new primal heuristic `octane`
8589 - slightly changed feaspump heuristic, s.t. after finding a new best solution the target integral solution is modified randomly
8590
8591- Separation and Cuts:
8592 - improved debugging for infeasible cuts and propagations, given a primal feasible solution
8593 - improved knapsack cover separation
8594 - improved performance of c-MIR separator
8595 - cut pool is now also separated in root node (to find cuts again that were removed from the LP due to aging)
8596
8597Interface changes
8598-----------------
8599
8600- new event type `SCIP_EVENTTYPE_VARDELETED`
8601- new event `SCIP_EVENTTYPE_IMPLADDED`
8602- new event types `SCIP_EVENTTYPE_GLBCHANGED` and `SCIP_EVENTTYPE_GUBCHANGED`
8603
8604### New and changed callbacks
8605
8606- new callback parameter `validnode` for the `CONFLICTEXEC` method of conflict handlers, which should be passed to
8607 SCIPaddConsNode()
8608
8609### Deleted and changed API methods
8610
8611- additional parameter `validnode` for SCIPaddConsLocal() and SCIPaddConsNode()
8612- SCIPhashtableRemove() can now also be called, if the element does not exist in the table
8613- SCIPhashmapRemove() can now also be called, if the element does not exist in the map
8614- additional parameter `branchdir` for SCIPbranchVar()
8615- replaced method SCIPmessage() by SCIPverbMessage() with additional parameter `file`
8616- put block memory shell and tclique algorithm into separate subdirectories
8617- new parameter `duringlploop` of SCIPincludeHeur(): heuristics can now run during the price-and-cut loop at a node
8618
8619### New API functions
8620
8621- SCIPgetNConflictClausesApplied()
8622- SCIPgetNConflictClausesApplied()
8623- SCIPhashtableExists()
8624- SCIPhashmapExists()
8625- SCIPnodeGetNumber()
8626- SCIPsolveProbingLP() to solve the LP in a probing node (enables mixing of propagation and LP solving for diving heuristics)
8627- SCIProwGetDualfarkas()
8628- SCIPgetCurrentNode()
8629- SCIPinterruptSolve()
8630- SCIPpropagateProbingImplications()
8631- SCIPgetLPI() which makes all methods in scip/lpi.h available to the user
8632- SCIPgetRandomInt() and SCIPgetRandomReal()
8633- SCIPstrtok()
8634- SCIPheurGetNBestSolsFound()
8635
8636- Variables:
8637 - SCIPdelVar()
8638 - SCIPgetVarStrongbranchLPAge()
8639 - SCIPvarIsTransformedOrigvar()
8640 - SCIPvarIsDeleted()
8641
8642- Messages and IO:
8643 - SCIPerrorMessage()
8644 - SCIPwarningMessage()
8645 - SCIPdialogMessage()
8646 - SCIPinfoMessage()
8647 - SCIPsetMessagehdlr()
8648 - SCIPsetDefaultMessagehdlr()
8649 - SCIPgetMessagehdlr()
8650 - new file i/o methods SCIPfopen(), SCIPfclose(), SCIPfprintf(), ... that operate on the data type `SCIPFILE`; these
8651 methods automatically use zlib methods if the zlib is enabled
8652
8653- Cliques:
8654 - SCIPvarGetNCliques()
8655 - SCIPvarGetCliques()
8656 - SCIPvarsHaveCommonClique()
8657 - SCIPvarHasImplic()
8658 - SCIPcliqueGetNVars()
8659 - SCIPcliqueGetVars()
8660 - SCIPcliqueGetValues()
8661 - SCIPcliqueGetId()
8662 - SCIPaddClique()
8663 - SCIPcalcCliquePartition()
8664
8665- Constraint handler:
8666 - SCIPgetDualfarkasLinear() of linear constraint handler
8667 - SCIPgetDualfarkasLogicor() of logicor constraint handler
8668 - SCIPgetDualfarkasSetppc() of setppc constraint handler
8669 - SCIPgetDualsolKnapsack() of knapsack constraint handler
8670 - SCIPgetDualfarkasKnapsack() of knapsack constraint handler
8671 - SCIPgetDualsolVarbound() of varbound constraint handler
8672 - SCIPgetDualfarkasVarbound() of varbound constraint handler
8673 - SCIPconsGetValidDepth()
8674 - SCIPsetConsInitial()
8675 - SCIPsetConsSeparated()
8676 - SCIPsetConsEnforced()
8677 - SCIPsetConsChecked()
8678 - SCIPsetConsPropagated()
8679 - SCIPsetConsLocal()
8680 - SCIPsetConsDynamic()
8681 - SCIPsetConsRemoveable()
8682
8683### Command line interface
8684
8685- added command `write solution` to default dialog
8686- added commands `write problem` and `write transproblem` to default dialog
8687
8688### Changed parameters
8689
8690- additional setting `SCIP_VERBLEVEL_DIALOG` in `display/verblevel` parameter
8691- additional LP pricing setting `partial`
8692- replaced parameter `presolving/restartbdchgs` with parameters `presolving/maxrestarts` and `presolving/restartfac`
8693- replaced parameter `constraints/linear/maxpresolaggrrounds` with `constraints/linear/maxpresolpairrounds`
8694- parameters `constraints/agelimit` and `constraints/obsoleteage` now iterprete the value 0 as a dynamic setting
8695- number of fractional variables included in parameter `separating/maxstallrounds`
8696
8697- Changed default values:
8698 - changed default values of `heuristics/∗/maxdiveavgquot` and `heuristics/∗/maxdiveavgquotnosol` to 0
8699 - changed default values of `constraints/agelimit` and `constraints/obsoleteage` to 0
8700 - changed default values of `heuristics/objpscostdiving/maxsols` and `heuristics/rootsoldiving/maxsols` to -1
8701 - changed default value of `separating/strongcg/maxroundsroot` to 20
8702 - changed default value of `separating/cmir/maxroundsroot` to 10
8703 - changed default value of `constraints/linear/maxaggrnormscale` to 0.0, which means to not apply aggregation
8704 - changed default value of `separating/maxstallrounds` to 5
8705 - changed default value of `presolving/probing/maxfixings` to 50
8706 - changed default parameter values to MIP settings:
8707 + `conflict/useprop` = FALSE
8708 + `conflict/usepseudo` = FALSE
8709 + `display/verblevel` = 4
8710 + `separating/poolfreq` = 0
8711 + `constraints/linear/sepafreq` = 0
8712 + `constraints/and/sepafreq` = 0
8713 + `constraints/conjunction/sepafreq` = 0
8714 + `constraints/knapsack/sepafreq` = 0
8715 + `constraints/knapsack/sepacardfreq` = 0
8716 + `constraints/logicor/sepafreq` = 0
8717 + `constraints/or/sepafreq` = 0
8718 + `constraints/setppc/sepafreq` = 0
8719 + `constraints/varbound/sepafreq` = 0
8720 + `constraints/xor/sepafreq` = 0
8721 + `separating/clique/freq` = 0
8722 + `separating/cmir/freq` = 0
8723 + `separating/gomory/freq` = 0
8724 + `separating/impliedbounds/freq` = 0
8725 + `separating/strongcg/freq` = 0
8726
8727### New parameters
8728
8729- `branching/fullstrong/reevalage`
8730- `conflict/maxclauses`
8731- `conflict/allowlocal`
8732- `constraints/knapsack/disaggregation`
8733- `presolving/probing/maxtotaluseless`
8734- `separating/cmir/maxfails`, `separating/cmir/maxfailsroot` and `separating/cmir/trynegscaling`
8735
8736### Data structures
8737
8738- MAJOR CHANGE: preceeded all data types with `SCIP_`: you may use shell script reptypes_scip.sh to rename the SCIP
8739 data types in your own source code (But use with care! Create a backup copy of your source first!)
8740
8741Build system
8742------------
8743
8744### Makefile
8745
8746- modified the Makefile to accept an additional parameter `VERBOSE={true,false}`
8747- added flags `READLINE=true/false`, `ZLIB=true/false`, `ZIMPL=true/false` to Makefile
8748
8749Fixed bugs
8750----------
8751
8752- fixed minor bugs in debug code of primal.c and sol.c
8753- variables that are being multiaggregated are now automatically removed from all other variables' variable bound and
8754 implication arrays; this fixes bugs with methods, that rely on the fact, that the entries in the variable bound and
8755 implication arrays are active variables only
8756- aggregations are now always performed in a way, such that the variable of more general type is aggregated (with type
8757 generality being cont > implint > int > bin); in this way, a binary variable's representant is always binary (which
8758 was not the case before and resulted in a bug in SCIPgetBinvarRepresentative())
8759- removed bug in presol_probing.c: the vars of the sorted variables array have to be captured
8760- fixed bug in the output of solutions with priced variables
8761- fixed bug in propagation with parameters prop_maxrounds and prop_maxroundsroot
8762- conflict analysis can now handle errors in LP solving calls
8763- removed bug in SCIPvarAddVlb() and SCIPvarAddVub() with fractional vlb/vubcoefs
8764- fixed bug that primal or dual rays might not be available because the wrong solver was used
8765- included message.o in LPI library, s.t. one can link this library indepentent of SCIP
8766- fixed bug that if diving heuristic that changes the objective values finds a solution, the cutoff is reinstalled in
8767 the LP solver (although the objective value has no meaning due to the objective function modification)
8768
8769- Feasibiltiy:
8770 - LP primal feasibility for bounds is now defined as absolute measure (was relative to the bound before); this fixes a bug (see alu8_9.mps),
8771 that an LP with an integral variable fixed to a large value yields an accepted solution with that variable slightly different than the fixed
8772 value; the integrality feasibility condition is measured with absolute differences, which leads to the fixed integer variable being fractional;
8773 this leads to an error if branching is performed on this variable
8774 - fixed bug with redundant self implications that wrongly lead to the detection of infeasibility
8775 - fixed bug with potential infinite loop if a separator is delayed and the LP is infeasible
8776
8777- Asserts:
8778 - removed wrong asserts from lpi_cpx.c
8779 - removed wrong assertion in varAddImplic()
8780
8781- Numerics:
8782 - locally fixed variables are no longer used as branching candidates even if their LP solution value is fractional (due
8783 to numerical reasons, see above)
8784 - fixed numerical bug in pseudo objective propagator with only slightly tightened bounds
8785 - removed bug that an LP might be declared to be solved even if it was marked erroneous due to numerical problems
8786
8787- Constraint Handlers:
8788 - fixed bug in linear constraint handler with variables fixed to infinity
8789 - fixed bug with constraint handlers that can only enforce their constraints by adding cuts, but the maximal number of
8790 cuts to separate is set to 0; now, cuts that are generated in the constraint enforcement are used in any case
8791 - fixed bug in knapsack constraint presolving with tightening coefficients and capacity
8792 - fixed bug with modifiable constraints in linear constraint handler preprocessing
8793 - fixed bug in linear constraint handler that global activities are not updated after global bound changes
8794
8795- Separation and Cuts:
8796 - global bound changes now lead to the removal of redundant implications (such that the asserts in sepa_implbounds.c are now correct)
8797 - due to usage of variable bounds, SCIPcalcMIR() may return LOOSE variables in the cut -> modified sepa_cmir.c, sepa_gomory.c and
8798 sepa_strongcg.c to use SCIPcreateEmptyRow() and SCIPaddVarsToRow() instead of SCIPcreateRow() which only works for COLs
8799 - fixed bug in clique separator that reduced performance
8800 - increased performance of clique separator by allowing only a certain number of zero-weighted fill ins
8801
8802@page RN07 Release notes for SCIP 0.7
8803
8804@section RN079 SCIP 0.7.9
8805*************************
8806
8807Features
8808--------
8809
8810- aging and cleanup now only remove non-basic columns and basic rows, s.t. resolving can be applied with 0 simplex iterations
8811- it is now possible to create subnodes in probing and use backtracking to undo probing changes
8812- bounds of variables are included in the feasibility checks for solutions
8813- support for barrier algorithm
8814- changed implementation of automatic minplungedepth and maxplungedepth calculation in bfs node selector
8815
8816- Presolving:
8817 - new plugin: probing presolver
8818 - probing is now also possible in presolving stage
8819 - it is now possible to interrupt and continue presolving
8820
8821- Separation and Cuts:
8822 - new plugin: clique separator for clique cuts with at least 3 elements
8823 - new plugin: implied bound cuts separator
8824 - included debugging module to check whether cutting planes cut off the optimal solution
8825
8826- Branching:
8827 - changed implementation of reliability value calculation in reliability branching; slightly modified influence of
8828 maximal total number of strong branching LP iterations in reliability branching
8829 - changed implementation of maximal strong branching iterations calculation in reliability branching
8830
8831- Constraints:
8832 - if verblevel is at least `NORMAL`, an automatical check of the best solution is performed in the original problem, and
8833 an error message is displayed, if it violates an original constraint
8834 - due to the new constraint handler `cons_cumulative.{c,h}` SCIP can resource-constraint scheduling problem
8835 - during probing, propagation of bounds is now always performed in linear constraint handler, ignoring the parameter `tightenboundsfreq`
8836 - new implementation of the clique graph construction method in clique separator
8837 - new constraint handler `cons_cumulative.{c,h}`
8838
8839- Heuristics:
8840 - new implementation of the feasibility pump heuristic by Timo Berthold (replaces old implementation); old
8841 implementation is now called `objfeaspump`; parameter names have been changed accordingly
8842 - diving heuristics now compare their number of LP iterations with the number of node LP iterations instead of the total
8843 number (including their own) LP iterations
8844 - modified the automatic objfactor setting of feaspump heuristic to let the objective function have stronger influence
8845
8846Examples and applications
8847-------------------------
8848
8849- added TSP example in `examples/TSP`
8850
8851Interface changes
8852-----------------
8853
8854### New and changed callbacks
8855
8856- new callback methods `INITSOL` and `EXITSOL` for variable pricers, primal heuristics, conflict handlers, relaxators,
8857 separators, propagators, event handlers, node selectors and display columns
8858- callback method `CONFLICTEXEC` of conflict handlers receive additional parameters `dynamic` and `removeable`
8859- constraint handler callback methods `CONSLOCK` and `CONSUNLOCK` are replaced by a single method `CONSLOCK` with the number
8860 of locks being positive or negative
8861
8862### Deleted and changed API methods
8863
8864- calling SCIPaddCut() with `forcecut=TRUE` will add the cut to the LP even if it is redundant
8865- SCIPreadProb() does not free the current problem, this is done in SCIPcreateProb() now, which is usually
8866 called by a problem reader; in this way, a reader can generate `extra information` for the current problem, s.t. the
8867 full problem information can be distributed to different files read by different readers
8868- SCIPgetVarStrongbranch() and SCIPgetVarStrongbranchLast() now have two additional parameters that can be used
8869 to check, whether the returned values are correct dual bounds
8870- SCIPgetBinvarRepresentative() now returns the fixed or multi-aggregated variable instead of returning `NULL` or
8871 aborting with an error message
8872- SCIPdispDecimal() is replaced by SCIPdispInt() and SCIPdispLongint()
8873- additional parameter `maxproprounds` in SCIPpropagateProbing()
8874- changed memory interface (see memory.h), `MEMHDR` is now called `BLKMEM`
8875- source code was moved into subdirectories: replace includes `scip.h` by `scip/scip.h` and
8876 `objscip.h` by `objscip/objscip.h`; This should allow a user to have include files of the same name as the ones
8877 of SCIP, e.g. `tree.h` or `var.h`.
8878- event handlers are now available as C++ wrapper class
8879- new flag `afterrelaxation` for primal heuristics
8880
8881- Solution:
8882 - removed method SCIPsolGetObj(), use SCIPgetSolOrigObj() or SCIPgetSolTransObj() instead
8883 - additional parameter `checkbounds` for SCIPtrySol(), SCIPtrySolFree(), SCIPcheckSol()
8884
8885- Variables:
8886 - SCIPvarLock(), SCIPvarLockDown(), SCIPvarLockUp(), SCIPvarLockBoth(), SCIPvarUnlock(), SCIPvarUnlockDown(),
8887 SCIPvarUnlockUp() and SCIPvarUnlockBoth() are replaced by SCIPaddVarLocks() which returns a `RETCODE`
8888 - SCIPvarGetLbGlobal(), SCIPvarGetUbGlobal(), SCIPvarGetLbLocal() and SCIPvarGetUbLocal() now return the
8889 corresponding values of the transformed problem or current subproblem even for original problem variables
8890 - SCIPvarGetProbvar(), SCIPvarGetProbvarBinary() now return the fixed or multi-aggregated variable instead of
8891 returning `NULL` or aborting with an error message; in SCIPvarGetProbvarBinary(), the fixing of a fixed variable does
8892 not influence the negation status anymore
8893 - SCIPvarGetProbvarBound() returns the multi-aggregated variable instead of aborting with an error message
8894 - SCIPvarGetProbvarSum() does not set *var to `NULL` for fixed variables anymore; it may also return a
8895 multi-aggregated variable instead of aborting with an error message
8896 - SCIPaddVarImplication() now also adds variable lower and upper bounds, if the implied variable is non-binary
8897 - additional parameter `aggregated` in SCIPmultiaggregateVars()
8898
8899- Constraints:
8900 - SCIPvarLockDownCons(), SCIPvarLockUpCons(), SCIPvarUnlockDownCons() and SCIPvarUnlockUpCons() are replaced by
8901 SCIPlockVarCons() and SCIPunlockVarCons() which return a `RETCODE`
8902 - SCIPlockConsVars() and SCIPunlockConsVars() replaced with method SCIPaddConsLocks()
8903 - SCIPconshdlrGetNConss() is replaced by SCIPconshdlrGetNActiveConss() (returning the number of active
8904 constraints); method SCIPconshdlrGetNConss() does now return the total number of existing constraints, active and inactive
8905 - SCIPconshdlrGetStartNConss() is now called SCIPconshdlrGetStartNActiveConss()
8906 - SCIPconshdlrGetMaxNConss() is now called SCIPconshdlrGetMaxNActiveConss()
8907 - SCIPdisableConsNode() is replaced by SCIPdelConsNode()
8908 - SCIPdisableConsLocal() is replaced by SCIPdelConsLocal()
8909 - added new parameter `dynamic` to SCIPcreateCons() and all plugin methods SCIPcreateCons...()
8910
8911### New API functions
8912
8913- SCIPgetObjNorm()
8914- SCIPcreateOrigSol()
8915- SCIPwriteImplicationConflictGraph()
8916- SCIPinProbing()
8917- SCIPgetProbName()
8918- SCIPgetVarNStrongbranchs()
8919- SCIPcolGetNStrongbranchs()
8920- SCIPfindSimpleRational()
8921- SCIPselectSimpleValue()
8922
8923- Variables:
8924 - SCIPvarGetLbOriginal()
8925 - SCIPvarGetUbOriginal()
8926 - SCIPvarGetImplIds()
8927 - SCIPvarGetOrigvarSum()
8928
8929- Constraints:
8930 - SCIPenableCons()
8931 - SCIPdisableCons()
8932 - SCIPenableConsSeparation()
8933 - SCIPdisableConsSeparation()
8934 - SCIPconsIsSeparationEnabled()
8935
8936- Averages:
8937 - SCIPgetAvgPseudocost()
8938 - SCIPgetAvgPseudocostCurrentRun()
8939 - SCIPgetAvgPseudocostCount()
8940 - SCIPgetAvgPseudocostCountCurrentRun()
8941 - SCIPgetAvgInferences()
8942 - SCIPgetAvgInferencesCurrentRun()
8943 - SCIPgetAvgCutoffs()
8944 - SCIPgetAvgCutoffsCurrentRun()
8945
8946- LPs:
8947 - SCIPisLPSolBasic() to check, whether the current LP solution is basic (i.e. due to a simplex algorithm or barrier with crossover)
8948 - SCIPgetNPrimalLPs()
8949 - SCIPgetNPrimalLPIterations()
8950 - SCIPgetNDualLPs()
8951 - SCIPgetNDualLPIterations()
8952 - SCIPgetNBarrierLPs()
8953 - SCIPgetNBarrierLPIterations()
8954 - SCIPgetNPrimalResolveLPs()
8955 - SCIPgetNPrimalResolveLPIterations()
8956 - SCIPgetNDualResolveLPs()
8957 - SCIPgetNDualResolveLPIterations()
8958
8959- Delayed:
8960 - SCIPsepaIsDelayed()
8961 - SCIPsepaWasDelayed()
8962 - SCIPpropIsDelayed()
8963 - SCIPpropWasDelayed()
8964 - SCIPpresolIsDelayed()
8965 - SCIPpresolWasDelayed()
8966 - SCIPconshdlrIsSeparationDelayed()
8967 - SCIPconshdlrIsPropagationDelayed()
8968 - SCIPconshdlrIsPresolvingDelayed()
8969 - SCIPconshdlrWasSeparationDelayed()
8970 - SCIPconshdlrWasPropagationDelayed()
8971 - SCIPconshdlrWasPresolvingDelayed()
8972
8973### Command line interface
8974
8975- command line history in interactive shell now only stores useful commands
8976
8977### Interfaces to external software
8978
8979- removed storing of dual norms in LPI state of CPLEX interface (too memory consuming)
8980
8981### Changed parameters
8982
8983- default frequency offset of fracdiving heuristic changed to 3
8984- default frequency offset of (new) feaspump heuristic changed to 0
8985- default frequency offset of objfeaspump heuristic changed to 8
8986- changed default priority of primal heuristics
8987- renamed parameter `limits/sol` to `limits/solutions`
8988- changed default check priority of knapsack constraint handler to -600000
8989- changed default priority of Gomory cut separator to -1000 (will now be called after constraint handlers!)
8990- changed default priority of strong CG cut separator to -2000
8991- changed default priority of cmir cut separator to -3000
8992- changed default of parameter `lp/pricing` to `s`teepest edge pricing
8993- default parameter `branching/relpscost/minreliable` changed to 1.0
8994- default parameter `branching/relpscost/maxlookahead` changed to 8
8995- default parameter `branching/relpscost/sbiterofs` changed to 100000
8996- default parameter `heuristics/coefdiving/maxlpiterquot` changed to 0.05
8997- default parameter `heuristics/fracdiving/maxlpiterquot` changed to 0.05
8998- default parameter `heuristics/guideddiving/maxlpiterquot` changed to 0.05
8999- default parameter `heuristics/linesearchdiving/maxlpiterquot` changed to 0.05
9000- default parameter `heuristics/pscostdiving/maxlpiterquot` changed to 0.05
9001- default parameter `heuristics/feaspump/freq` changed to 20
9002- default parameter `heuristics/objfeaspump/freq` changed to 20
9003- default parameter `heuristics/objpscostdiving/freq` changed to 20
9004- default parameter `heuristics/rootsoldiving/freq` changed to 20
9005- default parameter `separating/clique/maxtreenodes` changed to -1
9006
9007### New parameters
9008
9009- new parameter delay for presolvers
9010- new parameter delaypresol for constraint handlers
9011- `branching/scorefunc`
9012- `constraints/.../delaypresol`
9013- `constraints/.../delayprop`
9014- `constraints/.../delaysepa`
9015- `conflict/dynamic`
9016- `conflict/removeable`
9017- `heuristics/coefdiving/maxlpiterofs`
9018- `heuristics/feaspump/maxlpiterofs`
9019- `heuristics/feaspump/maxsols`
9020- `heuristics/fracdiving/maxlpiterofs`
9021- `heuristics/guideddiving/maxlpiterofs`
9022- `heuristics/linesearchdiving/maxlpiterofs`
9023- `heuristics/objfeaspump/maxlpiterofs`
9024- `heuristics/objfeaspump/maxsols`
9025- `heuristics/objpscostdiving/maxlpiterofs`
9026- `heuristics/objpscostdiving/maxsols`
9027- `heuristics/pscostdiving/maxlpiterofs`
9028- `heuristics/rootsoldiving/maxlpiterofs`
9029- `heuristics/rootsoldiving/maxsols`
9030- `heuristics/fixandinfer/proprounds` and `heuristics/fixandinfer/minfixings`
9031- `lp/cleanupcolsroot` and `lp/cleanuprowsroot` to distinguish cleanup settings between root node and other nodes
9032- `lp/checkstability` to disable stability check of LP solver's result code
9033- `lp/initalgorithm` and `lp/resolvealgorithm` for switching between simplex and barrier algorithm
9034- `lp/pricing` to set the pricing strategy used in the LP solver
9035- `numerics/barrierconvtol` to set the convergence tolerance in the barrier algorithm
9036- `presolving/.../delay`
9037- `propagating/.../delay`
9038- `reading/cnfreader/dynamicconss`
9039- `reading/mpsreader/dynamicconss`
9040- `separating/.../delay`
9041
9042### Data structures
9043
9044- new possible result `SCIP_DELAYED` for `EXEC` method of separators, presolvers and propagators and `SEPA`, `PROP` and
9045 `PRESOL` methods of constraint handlers
9046
9047Fixed bugs
9048----------
9049
9050- fixed bug in MPS file reader
9051- removed bug with applying reduced cost strengthening before pricing in all necessary variables
9052- negated variables must also be reset in SCIPvarInitSolve()
9053- fixed documentation of `CONSLOCK`-method (missing parameter `scip` in SCIPaddVarLocks())
9054- included missing `objrelax.h` in includes of objscip.h
9055- fixed bug that after a resolve and further preprocessing, existing primal solutions may get corrupted due to
9056 aggregations or fixings that are possible due to the primal bound (given by the best solution)
9057- fixed bug with primal bound becoming wrong, if in a prior run the optimal solution was found and the cutoff bound was
9058 thereby reduced due to further domain propagation w.r.t. the objective function
9059- fixed bug in SCIPisObjIntegral()
9060- fixed bug in SCIPprintError() with `file == NULL`
9061- heuristic's display character is now only shown the first time, the new solution was found
9062- fixed bug that SCIPreadProb() doesn't discard the transformed problem
9063- fixed bug with wrong euclidean norm calculation of row, if multiple coefficients for the same variable are added and
9064 the sorting of the row was delayed with SCIProwDelaySort()
9065- fixed bug with adding implications: wrong insertion position, if only the lower bound change was present but not the
9066 upper bound change
9067- fixed bug in SCIPvarAddImplics() with wrong variable used in varAdjustBd()
9068- fixed bug in method reduced() of tclique_branch.c with sorting nodes in V
9069
9070- LP:
9071 - removed bug with objective norm calculation and column variables not in the LP (pricing)
9072 - LP error on forced LP resolve (due to 0 unfixed integers) now leads to an error (instead of accepting the pseudo
9073 solution as feasible)
9074 - fixed bug in CPLEX LP interface with dual norms
9075
9076- Presolving:
9077 - fixed bug that presolving time is not counted to solving time, if presolving is called explicitly with SCIPpresolve()
9078 - fixed bug where presolving fixings are counted even if the variable was already fixed
9079 - removed bug with dual presolver, that declared a problem to be unbounded or infeasible, if it could fix a variable to
9080 infinity even if its objective value is zero
9081 - fixed bug in knapsack constraint handler that fixed variables are sometimes not removed in presolving
9082
9083- Numerics:
9084 - fixed bug with unresolved numerical troubles in LP that don't render the LP useless at the current node
9085 - fixed numerical bugs in rounding heuristic and rootsoldiving heuristic
9086
9087- Separator:
9088 - fixed bugs in separation store with single coefficient cuts that are converted into bound changes
9089 - at least one cut per separation round is added to the LP to avoid cycling, even if the cut is redundant
9090 - fixed bug in SCIProwCalcIntegralScalar() with rows consisting of only continuous variables (appeared in gomory cut
9091 separator on miplib/dcmulti.mps)
9092 - fixed bug in linear constraint handler's knapsack relaxation separator
9093 - fixed bugs in intobj separator
9094 - fixed bug in cmir separator with empty rows
9095 - fixed bug in implied bound cut separator: only implications between binary variables were generated before
9096
9097- Constraint Handlers:
9098 - removed bug in knapsack constraint handler with merging multiple items if more than two items of the same variable
9099 appear in the constraint
9100 - removed bug in knapsack constraint handler with merging negated variables of equal weight at the end of the variables' array
9101 - fixed bug in linear constraint handler with eventdatas, if the original constraint has no variables
9102 - fixed bug that `CONSLOCK` method of constraint handlers that don't need constraints is not called
9103 - fixeg bug in setppc constraint handler with pairs of aggregated variables in the same constraint
9104 - fixed bug with globally deleting constraints, that have attached rows which are therefore not released in exitsol methods
9105
9106- Conflict analysis:
9107 - removed conflict analysis of infeasible diving LP if pricing is activated
9108 - made conflict analysis available in presolving stage (for probing conflicts)
9109
9110@section RN078 SCIP 0.7.8
9111*************************
9112
9113Features
9114--------
9115
9116- changed SCIProwCalcIntegralScalar() to a slightly different algorithm
9117- improved knapsack relaxation in linear constraint handler separator to scale the constraint in order to get integral
9118 coefficients instead of just rounding down all coefficients
9119- improved presolving of linear constraint handler: aggregation of two constraints with equal coefficient vector into
9120 single constraint
9121- improved presolving of knapsack constraint handler: aggregation of equal or negated variables in same constraint
9122
9123- Plugins:
9124 + priority of separators, propagators and presolvers decide whether the plugin is called before the corresponding
9125 constraint handler methods or after: plugins with nonnegative priorities are called before, plugins with negative
9126 priorities are called after the constraint handlers
9127 + new plugin class for relaxators (external relaxations, that can be used in parallel with LP relaxations)
9128 + if more than one result code applies to a plugin's execution, it should return the one that is higher in the call's
9129 documentation list
9130
9131Interface changes
9132-----------------
9133
9134- even in optimized mode, the simple functions that are implemented as defines in the include files exist in the
9135 library, s.t. one can include the include files without `NDEBUG` and use the optimized library
9136
9137### New and changed callbacks
9138
9139- new branching rule plugin methods `INITSOL` and `EXITSOL`
9140
9141### Deleted and changed API methods
9142
9143- removed SCIPisFeasible(); use !SCIPisFeasNegative() instead
9144- SCIPisIntegral(), SCIPisFracIntegral(), SCIPfloor(), SCIPceil() and SCIPfrac() don't use the feasibility
9145 tolerance anymore (default: 1e-06); instead, they are using epsilon (default: 1e-09); instead, for handling
9146 integrality of a variable `in feasibility tolerances`, new methods SCIPisFeasIntegral(), SCIPisFeasFracIntegral(),
9147 SCIPfeasFloor(), SCIPfeasCeil() and SCIPfeasFrac() should be used
9148- in LPI, the semantics of SCIPlpiHasPrimalRay() and SCIPlpiHasDualRay() changed: methods return TRUE, if a ray exists
9149 and the solver can return it; new methods SCIPlpiExistsPrimalRay() and SCIPlpiExistsDualRay() check whether a ray
9150 exists without checking, if the solver knows and can return the ray
9151
9152### New API functions
9153
9154- SCIPvarIsInLP()
9155- SCIPgetLPColumnObjval() and SCIPgetLPLooseObjval()
9156- SCIPcalcIntegralScalar() with arbitrary array of Real values
9157- SCIPaddCoefKnapsack() in knapsack constraint handler
9158- SCIPisScalingIntegral() to check, whether the scaling of a value would lead to an integral value, measured
9159 against epsilon which is also scaled by the same scalar
9160- SCIPgetRealarrayMinIdx(), SCIPgetRealarrayMaxIdx(), SCIPgetIntarrayMinIdx(), SCIPgetIntarrayMaxIdx(),
9161 SCIPgetBoolarrayMinIdx(), SCIPgetBoolarrayMaxIdx(), SCIPgetPtrarrayMinIdx() and SCIPgetPtrarrayMaxIdx()
9162- SCIPbsortPtrInt() and SCIPbsortPtrIntInt()
9163- SCIPvarWasFixedAtIndex()
9164- SCIPaddConflictBd()
9165- SCIPprintMemoryDiagnostic()
9166- SCIPfindObj...() and SCIPgetObj...() in C++ wrapper interface to get the corresponding plugin object
9167
9168### Changed parameters
9169
9170- slightly changed the meaning of parameter `presolving/abortfac` a value of 0 now means to abort presolving only after
9171 no more change has been found
9172
9173Fixed bugs
9174----------
9175
9176- assigning a value to a fixed variable in a solution with SCIPsetSolVal() does not return an error anymore, if the
9177 value is equal to the fixed value of the variable
9178- removed bug in SCIPisScalingIntegral()
9179- removed bugs with calling SCIPtightenVarLb(), SCIPtightenVarUb(), SCIPinferVarLbCons(), SCIPinferVarUbCons(),
9180 SCIPinferVarLbProp() and SCIPinferVarUbProp() in `PROBLEM` stage
9181
9182- (Re)solving:
9183 - solving loop is now immediately aborted, if a node on the active path is marked to be cut off
9184 - removed bug in resolving an interrupted problem, after the last solved node was cut off
9185 - removed bug with infinite solving loop if LP solving is turned off
9186 - removed bug with aborted solving in root node (e.g. due to time limit) that is tagged to be restarted
9187
9188- Branching:
9189 - fixed bug in all-fullstrong branching with getting strong branching information for columns not in current LP
9190 - implemented missing case in solve.c with branching rules that add constraints
9191
9192- Numerics:
9193 - changed numerics for integrality check of coefficients (fixed bug with accumulated errors in rows s.t. the row's
9194 activity is no longer integral although the row is marked being integer)
9195 - slightly changed numerics in linear constraint handler presolving to fix a bug with coefficients detected to be scaled
9196 to an integral value, that are not integral after scaling due to a large scalar that increased the integrality gap to
9197 a value larger than epsilon
9198
9199- Constraint handlers:
9200 - fixed bugs in consdataSwitchWatchedVars() of `or` and `and` constraint handlers
9201 - fixed wrong assertion in xor constraint handler with switching both watched variables to unwatched
9202 - fixed bugs in constraint handlers (and, logicor, or, setppc, xor) with calling conflict analysis during presolving
9203 - removed bug in knapsack constraint handler that appears if a variable is fixed to zero in knapsack presolving, which
9204 triggers a variable of the same knapsack to be fixed to one due to aggregation
9205
9206- Presolving:
9207 - removed bug in knapsack presolver
9208 - fixed bug in presolving with wrong number of newly fixed/aggregated/... variables/bounds/... after a restart
9209
9210@section RN077 SCIP 0.7.7
9211*************************
9212
9213Features
9214--------
9215
9216- infeasible LPs in diving now produce conflict clauses (if LP conflict analysis is enabled)
9217- conflict analysis was slightly modified
9218- slightly changed aging strategy of logic or constraint handler
9219
9220Interface changes
9221-----------------
9222
9223### Deleted and changed API methods
9224
9225- method SCIPgetGap() and SCIPgetTransGap() now return infinity, if primal and dual bound have opposite sign (this
9226 removes the oddness with the gap increasing while the dual bound approaches zero)
9227
9228### New API functions
9229
9230- added methods SCIPgetVarsLogicor() and SCIPgetNVarsLogicor() in logic or constraint handler
9231
9232### Changed parameters
9233
9234- `lp/colagelimit` and `lp/rowagelimit` may now be set to -1 to disable deletion of columns/rows due to aging
9235
9236Build system
9237------------
9238
9239### Makefile
9240
9241- the file names in the archive file are now preceeded with a directory `scip-<version>/`
9242- the compiler is now also represented in the LP solver library names (e.g. you have to rename the softlink
9243 `libcplex.linux.x86.a` to `libcplex.linux.x86.gnu.a`)
9244
9245Fixed bugs
9246----------
9247
9248- removed bug in conflict analysis that appears if the conflict is only active at the current depth level
9249- missing SCIPlpiIsPrimalFeasible() and SCIPlpiIsDualFeasible() implemented in lpi_spx.cpp and lpi_spx121.cpp
9250- removed preprocessing of linear constraint pairs with modifiable constraints
9251
9252- Asserts:
9253 - removed wrong assert `assert(eventfilter->len == 0 || eventfilter->eventmask != 0x00000000)` from event.c
9254 - removed wrong assert in conflict analysis (appeared on analyzing diving LP conflicts with both bounds of a non-binary variable changed)
9255
9256@section RN076 SCIP 0.7.6
9257*************************
9258
9259Features
9260--------
9261
9262- creation of reconvergence clauses in conflict analysis
9263- first node of each plunging is not treated as plunging node w.r.t. calling primal heuristics
9264- improved performance of logic or constraint handler due to better watched variables handling
9265
9266Interface changes
9267-----------------
9268
9269### Deleted and changed API methods
9270
9271- changed SCIPcatchVarEvent() and SCIPdropVarEvent()
9272- SCIPstage() is now called SCIPgetStage()
9273- SCIPprintStatus() is now called SCIPprintStage()
9274
9275### New API functions
9276
9277- SCIPgetActivityLinear() in linear constraint handler
9278- SCIPgetFeasibilityLinear() in linear constraint handler
9279- SCIPchgVarBranchDirection()
9280- SCIPvarGetBranchDirection()
9281- SCIPgetStatus() returns the solution status
9282- SCIPprintStatus() outputs the solution status (beware, that the old SCIPprintStatus() method is now called SCIPprintStage())
9283
9284### Changed parameters
9285
9286- changed default frequency offset of pscostdiving `heuristics/pscostdiving/freqofs` to 2 and frequency offset of fracdiving
9287 `heuristics/feaspump/freqofs` to 0 in order to not call pscostdiving in root node, where nearly all pseudo costs are uninitialized.
9288
9289### New parameters
9290
9291- new parameter `separating/efficacynorm` to choose between Euclidean, maximum, sum and discrete norm in efficacy
9292 calculation
9293
9294### Data structures
9295
9296- new possible result code `SCIP_DELAYED` for primal heuristics
9297
9298Fixed bugs
9299----------
9300
9301- removed bugs in CLP Solver interface
9302- SCIP returned `gap limit reached` even if the problem was solved to optimality, if the optimal solution was found at a
9303 node with lower bound equal to the global lower bound
9304- after conversion of the focus node into a junction (e.g. in case of numerical troubles while solving the node's LP), the child
9305 nodes got the wrong LP fork attached (the common LP fork of the old and new focus node instead of the old focus node's LP fork)
9306
9307- Variables:
9308 - bug reconvergence clauses in conflict analysis if bounds on non-binary variables were the reason for the fixing of the
9309 uip to create a reconvergence clause for
9310 - wrong sub calls in SCIPvarGet...CurrentRun() for aggregated variables
9311 - variables' conflict set counter was not reset when the problem was resolved again
9312
9313Known bugs
9314----------
9315
9316- unbounded models lead to an error
9317- air04 and air05 return wrong optimal value (1 too large): possibly due to strong branching or setppc propagation?
9318
9319@section RN075 SCIP 0.7.5
9320*************************
9321
9322Miscellaneous
9323-------------
9324
9325- started change log*/