Scippy

SCIP

Solving Constraint Integer Programs

Detailed Description

propagator for handling symmetries

Author
Marc Pfetsch
Thomas Rehn
Christopher Hojny

This propagator combines the following symmetry handling functionalities:

  • It allows to compute symmetries of the problem and to store this information in adequate form. The symmetry information can be accessed through external functions.
  • It allows to add the following symmetry breaking constraints:
    • symresack constraints, which separate minimal cover inequalities
    • orbitope constraints, if special symmetry group structures are detected
  • It allows to apply orbital fixing.

Symmetry Computation

The following comments apply to symmetry computation.

  • The generic functionality of the compute_symmetry.h interface is used.
  • We treat implicit integer variables as if they were continuous/real variables. The reason is that there is currently no distinction between implicit integer and implicit binary. Moreover, currently implicit integer variables hurt our code more than continuous/real variables (we basically do not handle integral variables at all).
  • We do not copy symmetry information, since it is not clear how this information transfers. Moreover, copying symmetry might inhibit heuristics. But note that solving a sub-SCIP might then happen without symmetry information!

Symmetry Handling Constraints

The following comments apply to adding symmetry handling constraints.

  • The code automatically detects whether symmetry substructures like symresacks or orbitopes are present and possibly adds the corresponding constraints.
  • If orbital fixing is active, only orbitopes are added (if present) and no symresacks.
  • We try to compute symmetry as late as possible and then add constraints based on this information.
  • Currently, we only allocate memory for pointers to symresack constraints for group generators. If further constraints are considered, we have to reallocate memory.

Orbital Fixing

Orbital fixing is implemented as introduced by
F. Margot: Exploiting orbits in symmetric ILP. Math. Program., 98(1-3):3–21, 2003.

The method computes orbits of variables with respect to the subgroup of the symmetry group that stabilizes the variables globally fixed or branched to 1. Then one can fix all variables in an orbit to 0 or 1 if one of the other variables in the orbit is fixed to 0 or 1, respectively. Different from Margot, the subgroup is obtained by filtering out generators that do not individually stabilize the variables branched to 1.

Precondition
All variable fixings applied by other components are required to be strict, i.e., if one variable is fixed to a certain value v, all other variables in the same variable orbit can be fixed to v as well, c.f.
F. Margot: Symmetry in integer linear programming. 50 Years of Integer Programming, 647-686, Springer 2010.

To illustrate this, consider the example \(\max\{x_1 + x_2 : x_1 + x_2 \leq 1, Ay \leq b, (x,y) \in \{0,1\}^{2 + n}\} \). Since \(x_1\) and \(x_2\) are independent from the remaining problem, the setppc constraint handler may fix \((x_1,x_2) = (1,0)\). However, since both variables are symmetric, this setting is not strict (if it was strict, both variables would have been set to the same value) and orbital fixing would declare this subsolution as infeasible (there exists an orbit of non-branching variables that are fixed to different values). To avoid this situation, we have to assume that all non-strict settings fix variables globally, i.e., we can take care of it by taking variables into account that have been globally fixed to 1. In fact, it suffices to consider one kind of global fixings since stabilizing one kind prevents an orbit to contain variables that have been fixed globally to different values.

Precondition
All non-strict settings are global settings, since otherwise, we cannot (efficiently) take care of them.
No non-strict setting algorithm is interrupted early (e.g., by a time or iteration limit), since this may lead to wrong decisions by orbital fixing as well. For example, if cons_setppc in the above toy example starts by fixing \(x_2 = 0\) and is interrupted afterwards, orbital fixing detects that the orbit \(\{x_1, x_2\}\) contains one variable that is fixed to 0, and thus, it fixes \(x_1\) to 0 as well. Thus, after these reductions, every feasible solution has objective 0 which is not optimal. This situation would not occur if the non-strict setting is complete, because then \(x_1\) is globally fixed to 1, and thus, is stabilized in orbital fixing.

Note that orbital fixing might lead to wrong results if it is called in repropagation of a node, because the path from the node to the root might have been changed. Thus, the stabilizers of global 1-fixing and 1-branchings of the initial propagation and repropagation might differ, which may cause conflicts. For this reason, orbital fixing cannot be called in repropagation.

Note
If, besides orbital fixing, also symmetry handling constraints shall be added, orbital fixing is only applied to symmetry components that are not handled by orbitope constraints.

Definition in file prop_symmetry.c.

#include <scip/cons_linear.h>
#include <scip/cons_knapsack.h>
#include <scip/cons_varbound.h>
#include <scip/cons_setppc.h>
#include <scip/cons_and.h>
#include <scip/cons_logicor.h>
#include <scip/cons_or.h>
#include "scip/cons_orbitope.h"
#include "scip/cons_symresack.h"
#include <scip/cons_xor.h>
#include <scip/cons_linking.h>
#include <scip/cons_bounddisjunction.h>
#include <scip/misc.h>
#include <scip/prop_symmetry.h>
#include <symmetry/compute_symmetry.h>
#include <scip/symmetry.h>
#include <string.h>

Go to the source code of this file.

Data Structures

struct  SYM_Sortrhstype
 

Macros

#define PROP_NAME   "symmetry"
 
#define PROP_DESC   "propagator for handling symmetry"
 
#define PROP_TIMING   SCIP_PROPTIMING_BEFORELP
 
#define PROP_PRIORITY   -1000000
 
#define PROP_FREQ   1
 
#define PROP_DELAY   FALSE
 
#define PROP_PRESOL_PRIORITY   -10000000
 
#define PROP_PRESOLTIMING   SCIP_PRESOLTIMING_EXHAUSTIVE /* timing of the presolving method (fast, medium, or exhaustive) */
 
#define PROP_PRESOL_MAXROUNDS   -1
 
#define DEFAULT_MAXGENERATORS   1500
 
#define DEFAULT_CHECKSYMMETRIES   FALSE
 
#define DEFAULT_DISPLAYNORBITVARS   FALSE
 
#define DEFAULT_USECOLUMNSPARSITY   FALSE
 
#define DEFAULT_DOUBLEEQUATIONS   FALSE
 
#define DEFAULT_COMPRESSSYMMETRIES   TRUE
 
#define DEFAULT_COMPRESSTHRESHOLD   0.5
 
#define DEFAULT_SYMFIXNONBINARYVARS   FALSE
 
#define DEFAULT_CONSSADDLP   TRUE
 
#define DEFAULT_ADDSYMRESACKS   TRUE
 
#define DEFAULT_DETECTORBITOPES   TRUE
 
#define DEFAULT_ADDCONSSTIMING   2
 
#define DEFAULT_OFSYMCOMPTIMING   2
 
#define DEFAULT_PERFORMPRESOLVING   FALSE
 
#define DEFAULT_RECOMPUTERESTART   FALSE
 
#define DEFAULT_DISABLEOFRESTART   FALSE
 
#define EVENTHDLR_SYMMETRY_NAME   "symmetry"
 
#define EVENTHDLR_SYMMETRY_DESC   "filter global variable fixing event handler for orbital fixing"
 
#define TABLE_NAME_ORBITALFIXING   "orbitalfixing"
 
#define TABLE_DESC_ORBITALFIXING   "orbital fixing statistics"
 
#define TABLE_POSITION_ORBITALFIXING   7001
 
#define TABLE_EARLIEST_ORBITALFIXING   SCIP_STAGE_SOLVING
 
#define MAXGENNUMERATOR   64000000
 
#define SCIP_SPECIALVAL   1.12345678912345e+19
 
#define COMPRESSNVARSLB   25000
 
#define ISSYMRETOPESACTIVE(x)   (((unsigned) x & SYM_HANDLETYPE_SYMBREAK) != 0)
 
#define ISORBITALFIXINGACTIVE(x)   (((unsigned) x & SYM_HANDLETYPE_ORBITALFIXING) != 0)
 

Typedefs

typedef struct SYM_Sortrhstype SYM_SORTRHSTYPE
 

Functions

static SCIP_DECL_EVENTEXEC (eventExecSymmetry)
 
static SCIP_DECL_TABLEOUTPUT (tableOutputOrbitalfixing)
 
static SCIP_DECL_TABLEFREE (tableFreeOrbitalfixing)
 
static SCIP_DECL_HASHGETKEY (SYMhashGetKeyVartype)
 
static SCIP_DECL_HASHKEYEQ (SYMhashKeyEQVartype)
 
static SCIP_DECL_HASHKEYVAL (SYMhashKeyValVartype)
 
static SCIP_DECL_SORTINDCOMP (SYMsortRhsTypes)
 
static SCIP_DECL_SORTINDCOMP (SYMsortMatCoef)
 
static SCIP_Bool checkSymmetryDataFree (SCIP_PROPDATA *propdata)
 
static SCIP_RETCODE freeSymmetryData (SCIP *scip, SCIP_PROPDATA *propdata)
 
static SCIP_RETCODE delSymConss (SCIP *scip, SCIP_PROPDATA *propdata)
 
static SCIP_Bool SymmetryFixVar (SYM_SPEC fixedtype, SCIP_VAR *var)
 
static SCIP_RETCODE getActiveVariables (SCIP *scip, SCIP_VAR ***vars, SCIP_Real **scalars, int *nvars, SCIP_Real *constant, SCIP_Bool transformed)
 
static SCIP_RETCODE collectCoefficients (SCIP *scip, SCIP_Bool doubleequations, SCIP_VAR **linvars, SCIP_Real *linvals, int nlinvars, SCIP_Real lhs, SCIP_Real rhs, SCIP_Bool istransformed, SYM_RHSSENSE rhssense, SYM_MATRIXDATA *matrixdata, int *nconssforvar)
 
static SCIP_RETCODE checkSymmetriesAreSymmetries (SCIP *scip, SYM_SPEC fixedtype, SYM_MATRIXDATA *matrixdata, int nperms, int **perms)
 
static int getNSymhandableConss (SCIP *scip)
 
static SCIP_RETCODE setSymmetryData (SCIP *scip, SCIP_VAR **vars, int nvars, int nbinvars, SCIP_VAR ***permvars, int *npermvars, int *nbinpermvars, int **perms, int nperms, int *nmovedvars, SCIP_Bool *binvaraffected, SCIP_Bool usecompression, SCIP_Real compressthreshold, SCIP_Bool *compressed)
 
static SCIP_RETCODE computeSymmetryGroup (SCIP *scip, SCIP_Bool doubleequations, SCIP_Bool compresssymmetries, SCIP_Real compressthreshold, int maxgenerators, SYM_SPEC fixedtype, SCIP_Bool local, SCIP_Bool checksymmetries, SCIP_Bool usecolumnsparsity, int *npermvars, int *nbinpermvars, SCIP_VAR ***permvars, int *nperms, int *nmaxperms, int ***perms, SCIP_Real *log10groupsize, int *nmovedvars, SCIP_Bool *binvaraffected, SCIP_Bool *compressed, SCIP_Bool *success)
 
static SCIP_RETCODE determineSymmetry (SCIP *scip, SCIP_PROPDATA *propdata, SYM_SPEC symspecrequire, SYM_SPEC symspecrequirefixed)
 
static SCIP_RETCODE detectOrbitopes (SCIP *scip, SCIP_PROPDATA *propdata, int *components, int *componentbegins, int ncomponents)
 
static SCIP_RETCODE addSymresackConss (SCIP *scip, SCIP_PROP *prop, int *components, int *componentbegins, int ncomponents)
 
static SCIP_RETCODE tryAddSymmetryHandlingConss (SCIP *scip, SCIP_PROP *prop, SCIP_Bool *earlyterm)
 
static SCIP_RETCODE performOrbitalFixing (SCIP *scip, SCIP_VAR **permvars, int npermvars, int *orbits, int *orbitbegins, int norbits, SCIP_Bool *infeasible, int *nfixedzero, int *nfixedone)
 
static SCIP_RETCODE computeBranchingVariables (SCIP *scip, int nvars, SCIP_HASHMAP *varmap, SCIP_Shortbool *bg1, int *bg1list, int *nbg1)
 
static SCIP_RETCODE propagateOrbitalFixing (SCIP *scip, SCIP_PROPDATA *propdata, SCIP_Bool *infeasible, int *nprop)
 
static SCIP_DECL_PROPINITPRE (propInitpreSymmetry)
 
static SCIP_DECL_PROPEXITPRE (propExitpreSymmetry)
 
static SCIP_DECL_PROPPRESOL (propPresolSymmetry)
 
static SCIP_DECL_PROPEXEC (propExecSymmetry)
 
static SCIP_DECL_PROPEXIT (propExitSymmetry)
 
static SCIP_DECL_PROPRESPROP (propRespropSymmetry)
 
static SCIP_DECL_PROPFREE (propFreeSymmetry)
 
SCIP_RETCODE SCIPincludePropSymmetry (SCIP *scip)
 
SCIP_RETCODE SCIPgetSymmetry (SCIP *scip, int *npermvars, SCIP_VAR ***permvars, SCIP_HASHMAP **permvarmap, int *nperms, int ***perms, int ***permstrans, SCIP_Real *log10groupsize, SCIP_Bool *binvaraffected, int **components, int **componentbegins, int **vartocomponent, int *ncomponents)
 
SCIP_Bool SCIPisOrbitalfixingEnabled (SCIP *scip)
 
int SCIPgetSymmetryNGenerators (SCIP *scip)
 

Macro Definition Documentation

◆ PROP_NAME

◆ PROP_DESC

#define PROP_DESC   "propagator for handling symmetry"

Definition at line 134 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ PROP_TIMING

#define PROP_TIMING   SCIP_PROPTIMING_BEFORELP

propagation timing mask

Definition at line 135 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ PROP_PRIORITY

#define PROP_PRIORITY   -1000000

propagator priority

Definition at line 136 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ PROP_FREQ

#define PROP_FREQ   1

propagator frequency

Definition at line 137 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ PROP_DELAY

#define PROP_DELAY   FALSE

should propagation method be delayed, if other propagators found reductions?

Definition at line 138 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ PROP_PRESOL_PRIORITY

#define PROP_PRESOL_PRIORITY   -10000000

priority of the presolving method (>= 0: before, < 0: after constraint handlers)

Definition at line 140 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ PROP_PRESOLTIMING

#define PROP_PRESOLTIMING   SCIP_PRESOLTIMING_EXHAUSTIVE /* timing of the presolving method (fast, medium, or exhaustive) */

Definition at line 141 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ PROP_PRESOL_MAXROUNDS

#define PROP_PRESOL_MAXROUNDS   -1

maximal number of presolving rounds the presolver participates in (-1: no limit)

Definition at line 142 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_MAXGENERATORS

#define DEFAULT_MAXGENERATORS   1500

limit on the number of generators that should be produced within symmetry detection (0 = no limit)

Definition at line 146 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_CHECKSYMMETRIES

#define DEFAULT_CHECKSYMMETRIES   FALSE

Should all symmetries be checked after computation?

Definition at line 147 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_DISPLAYNORBITVARS

#define DEFAULT_DISPLAYNORBITVARS   FALSE

Should the number of variables affected by some symmetry be displayed?

Definition at line 148 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_USECOLUMNSPARSITY

#define DEFAULT_USECOLUMNSPARSITY   FALSE

Should the number of conss a variable is contained in be exploited in symmetry detection?

Definition at line 149 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_DOUBLEEQUATIONS

#define DEFAULT_DOUBLEEQUATIONS   FALSE

Double equations to positive/negative version?

Definition at line 150 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_COMPRESSSYMMETRIES

#define DEFAULT_COMPRESSSYMMETRIES   TRUE

Should non-affected variables be removed from permutation to save memory?

Definition at line 151 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_COMPRESSTHRESHOLD

#define DEFAULT_COMPRESSTHRESHOLD   0.5

Compression is used if percentage of moved vars is at most the threshold.

Definition at line 152 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_SYMFIXNONBINARYVARS

#define DEFAULT_SYMFIXNONBINARYVARS   FALSE

Whether all non-binary variables shall be not affected by symmetries if OF is active?

Definition at line 153 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_CONSSADDLP

#define DEFAULT_CONSSADDLP   TRUE

Should the symmetry breaking constraints be added to the LP?

Definition at line 156 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_ADDSYMRESACKS

#define DEFAULT_ADDSYMRESACKS   TRUE

Add inequalities for symresacks for each generator?

Definition at line 157 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_DETECTORBITOPES

#define DEFAULT_DETECTORBITOPES   TRUE

Should we check whether the components of the symmetry group can be handled by orbitopes?

Definition at line 158 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_ADDCONSSTIMING

#define DEFAULT_ADDCONSSTIMING   2

timing of adding constraints (0 = before presolving, 1 = during presolving, 2 = after presolving)

Definition at line 159 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_OFSYMCOMPTIMING

#define DEFAULT_OFSYMCOMPTIMING   2

timing of symmetry computation for orbital fixing (0 = before presolving, 1 = during presolving, 2 = at first call)

Definition at line 162 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_PERFORMPRESOLVING

#define DEFAULT_PERFORMPRESOLVING   FALSE

Run orbital fixing during presolving?

Definition at line 163 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_RECOMPUTERESTART

#define DEFAULT_RECOMPUTERESTART   FALSE

Recompute symmetries after a restart has occurred?

Definition at line 164 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ DEFAULT_DISABLEOFRESTART

#define DEFAULT_DISABLEOFRESTART   FALSE

whether OF shall be disabled if OF has found a reduction and a restart occurs

Definition at line 165 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ EVENTHDLR_SYMMETRY_NAME

#define EVENTHDLR_SYMMETRY_NAME   "symmetry"

Definition at line 169 of file prop_symmetry.c.

Referenced by SCIP_DECL_EVENTEXEC(), and SCIPincludePropSymmetry().

◆ EVENTHDLR_SYMMETRY_DESC

#define EVENTHDLR_SYMMETRY_DESC   "filter global variable fixing event handler for orbital fixing"

Definition at line 170 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ TABLE_NAME_ORBITALFIXING

#define TABLE_NAME_ORBITALFIXING   "orbitalfixing"

Definition at line 173 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ TABLE_DESC_ORBITALFIXING

#define TABLE_DESC_ORBITALFIXING   "orbital fixing statistics"

Definition at line 174 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ TABLE_POSITION_ORBITALFIXING

#define TABLE_POSITION_ORBITALFIXING   7001

the position of the statistics table

Definition at line 175 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ TABLE_EARLIEST_ORBITALFIXING

#define TABLE_EARLIEST_ORBITALFIXING   SCIP_STAGE_SOLVING

output of the statistics table is only printed from this stage onwards

Definition at line 176 of file prop_symmetry.c.

Referenced by SCIPincludePropSymmetry().

◆ MAXGENNUMERATOR

#define MAXGENNUMERATOR   64000000

determine maximal number of generators by dividing this number by the number of variables

Definition at line 180 of file prop_symmetry.c.

Referenced by determineSymmetry().

◆ SCIP_SPECIALVAL

#define SCIP_SPECIALVAL   1.12345678912345e+19

special floating point value for handling zeros in bound disjunctions

Definition at line 181 of file prop_symmetry.c.

Referenced by computeSymmetryGroup().

◆ COMPRESSNVARSLB

#define COMPRESSNVARSLB   25000

lower bound on the number of variables above which compression could be performed

Definition at line 182 of file prop_symmetry.c.

Referenced by setSymmetryData().

◆ ISSYMRETOPESACTIVE

#define ISSYMRETOPESACTIVE (   x)    (((unsigned) x & SYM_HANDLETYPE_SYMBREAK) != 0)

Definition at line 185 of file prop_symmetry.c.

Referenced by SCIP_DECL_PROPEXEC(), and SCIP_DECL_PROPINITPRE().

◆ ISORBITALFIXINGACTIVE

#define ISORBITALFIXINGACTIVE (   x)    (((unsigned) x & SYM_HANDLETYPE_ORBITALFIXING) != 0)

Definition at line 186 of file prop_symmetry.c.

Referenced by freeSymmetryData(), SCIP_DECL_PROPEXEC(), and SCIP_DECL_PROPINITPRE().

Typedef Documentation

◆ SYM_SORTRHSTYPE

Definition at line 464 of file prop_symmetry.c.

Function Documentation

◆ SCIP_DECL_EVENTEXEC()

static SCIP_DECL_EVENTEXEC ( eventExecSymmetry  )
static

exec the event handler for handling global variable bound changes (necessary for orbital fixing)

Global variable fixings during the solving process might arise because parts of the tree are pruned or if certain preprocessing steps are performed that do not correspond to strict setting algorithms. Since these fixings might be caused by or be in conflict with orbital fixing, they can be in conflict with the symmetry handling decisions of orbital fixing in the part of the tree that is not pruned. Thus, we have to take global fixings into account when filtering out symmetries.

Definition at line 284 of file prop_symmetry.c.

References EVENTHDLR_SYMMETRY_NAME, NULL, SCIP_EVENTTYPE_GLBCHANGED, SCIP_EVENTTYPE_GUBCHANGED, SCIP_INVALIDDATA, SCIP_OKAY, SCIP_VARTYPE_BINARY, SCIPABORT, SCIPdebugMsg, SCIPerrorMessage, SCIPeventGetNewbound(), SCIPeventGetOldbound(), SCIPeventGetType(), SCIPeventGetVar(), SCIPeventhdlrGetName(), SCIPhashmapExists(), SCIPhashmapGetImageInt(), SCIPisEQ(), SCIPvarGetName(), SCIPvarGetType(), and TRUE.

◆ SCIP_DECL_TABLEOUTPUT()

static SCIP_DECL_TABLEOUTPUT ( tableOutputOrbitalfixing  )
static

output method of orbital fixing propagator statistics table to output file stream 'file'

Definition at line 360 of file prop_symmetry.c.

References NULL, SCIP_OKAY, SCIP_VERBLEVEL_MINIMAL, SCIPtableGetData(), and SCIPverbMessage().

◆ SCIP_DECL_TABLEFREE()

static SCIP_DECL_TABLEFREE ( tableFreeOrbitalfixing  )
static

destructor of statistics table to free user data (called when SCIP is exiting)

Definition at line 384 of file prop_symmetry.c.

References NULL, SCIP_OKAY, SCIPfreeBlockMemory, and SCIPtableGetData().

◆ SCIP_DECL_HASHGETKEY()

static SCIP_DECL_HASHGETKEY ( SYMhashGetKeyVartype  )
static

gets the key of the given element

Definition at line 403 of file prop_symmetry.c.

◆ SCIP_DECL_HASHKEYEQ()

static SCIP_DECL_HASHKEYEQ ( SYMhashKeyEQVartype  )
static

returns TRUE iff both keys are equal

Compare the types of two variables according to objective, lower and upper bound, variable type, and column sparsity.

Definition at line 413 of file prop_symmetry.c.

References FALSE, SYM_Vartype::lb, SYM_Vartype::nconss, SYM_Vartype::obj, SCIPisEQ(), TRUE, SYM_Vartype::type, and SYM_Vartype::ub.

◆ SCIP_DECL_HASHKEYVAL()

static SCIP_DECL_HASHKEYVAL ( SYMhashKeyValVartype  )
static

returns the hash value of the key

Definition at line 448 of file prop_symmetry.c.

References SYM_Vartype::lb, SYM_Vartype::nconss, SYM_Vartype::obj, SCIPhashFour, SCIPrealHashCode(), and SYM_Vartype::ub.

◆ SCIP_DECL_SORTINDCOMP() [1/2]

static SCIP_DECL_SORTINDCOMP ( SYMsortRhsTypes  )
static

sorts rhs types - first by sense, then by value

Due to numerical issues, we first sort by sense, then by value.

result: < 0: ind1 comes before (is better than) ind2 = 0: both indices have the same value

0: ind2 comes after (is worse than) ind2

Definition at line 476 of file prop_symmetry.c.

References SYM_Sortrhstype::nrhscoef, SCIP_Real, SYM_Sortrhstype::senses, and SYM_Sortrhstype::vals.

◆ SCIP_DECL_SORTINDCOMP() [2/2]

static SCIP_DECL_SORTINDCOMP ( SYMsortMatCoef  )
static

sorts matrix coefficients

result: < 0: ind1 comes before (is better than) ind2 = 0: both indices have the same value

0: ind2 comes after (is worse than) ind2

Definition at line 510 of file prop_symmetry.c.

References SCIP_Real, and SYM_Sortrhstype::vals.

◆ checkSymmetryDataFree()

static SCIP_Bool checkSymmetryDataFree ( SCIP_PROPDATA propdata)
static

checks that symmetry data is all freed

Parameters
propdatapropagator data

Definition at line 536 of file prop_symmetry.c.

References FALSE, NULL, and TRUE.

Referenced by determineSymmetry(), and freeSymmetryData().

◆ freeSymmetryData()

◆ delSymConss()

static SCIP_RETCODE delSymConss ( SCIP scip,
SCIP_PROPDATA propdata 
)
static

deletes symmetry handling constraints

Parameters
scipSCIP pointer
propdatapropagator data

Definition at line 732 of file prop_symmetry.c.

References FALSE, NULL, SCIP_CALL, SCIP_OKAY, SCIPdelCons(), SCIPfreeBlockMemoryArray, and SCIPreleaseCons().

Referenced by determineSymmetry().

◆ SymmetryFixVar()

static SCIP_Bool SymmetryFixVar ( SYM_SPEC  fixedtype,
SCIP_VAR var 
)
static

determines whether variable should be fixed by permutations

Parameters
fixedtypebitset of variable types that should be fixed
varvariable to be considered

Definition at line 773 of file prop_symmetry.c.

References FALSE, SCIP_VARTYPE_BINARY, SCIP_VARTYPE_CONTINUOUS, SCIP_VARTYPE_IMPLINT, SCIP_VARTYPE_INTEGER, SCIPvarGetType(), SYM_SPEC_BINARY, SYM_SPEC_INTEGER, SYM_SPEC_REAL, and TRUE.

Referenced by checkSymmetriesAreSymmetries(), and computeSymmetryGroup().

◆ getActiveVariables()

static SCIP_RETCODE getActiveVariables ( SCIP scip,
SCIP_VAR ***  vars,
SCIP_Real **  scalars,
int *  nvars,
SCIP_Real constant,
SCIP_Bool  transformed 
)
static

Transforms given variables, scalars, and constant to the corresponding active variables, scalars, and constant.

Note
constant needs to be initialized!
Parameters
scipSCIP data structure
varspointer to vars array to get active variables for
scalarspointer to scalars a_1, ..., a_n in linear sum a_1*x_1 + ... + a_n*x_n + c
nvarspointer to number of variables and values in vars and vals array
constantpointer to constant c in linear sum a_1*x_1 + ... + a_n*x_n + c
transformedtransformed constraint?

Definition at line 794 of file prop_symmetry.c.

References NULL, SCIP_CALL, SCIP_OKAY, SCIPgetProbvarLinearSum(), SCIPreallocBufferArray, SCIPvarGetOrigvarSum(), and TRUE.

Referenced by collectCoefficients().

◆ collectCoefficients()

static SCIP_RETCODE collectCoefficients ( SCIP scip,
SCIP_Bool  doubleequations,
SCIP_VAR **  linvars,
SCIP_Real linvals,
int  nlinvars,
SCIP_Real  lhs,
SCIP_Real  rhs,
SCIP_Bool  istransformed,
SYM_RHSSENSE  rhssense,
SYM_MATRIXDATA matrixdata,
int *  nconssforvar 
)
static

fills in matrix elements into coefficient arrays

Parameters
scipSCIP data structure
doubleequationsDouble equations to positive/negative version?
linvarsarray of linear variables
linvalsarray of linear coefficients values (or NULL if all linear coefficient values are 1)
nlinvarsnumber of linear variables
lhsleft hand side
rhsright hand side
istransformedwhether the constraint is transformed
rhssenseidentifier of constraint type
matrixdatamatrix data to be filled in
nconssforvarpointer to array to store for each var the number of conss

Definition at line 840 of file prop_symmetry.c.

References FALSE, getActiveVariables(), SYM_Matrixdata::matcoef, SYM_Matrixdata::matidx, SYM_Matrixdata::matrhsidx, SYM_Matrixdata::matvaridx, SYM_Matrixdata::nmatcoef, SYM_Matrixdata::nmaxmatcoef, SYM_Matrixdata::nrhscoef, SYM_Sortrhstype::nrhscoef, NULL, SYM_Matrixdata::rhscoef, SYM_Matrixdata::rhsidx, SYM_Matrixdata::rhssense, SCIP_Bool, SCIP_CALL, SCIP_OKAY, SCIP_Real, SCIPallocBufferArray, SCIPcalcMemGrowSize(), SCIPdebugMsg, SCIPduplicateBufferArray, SCIPfreeBufferArray, SCIPgetNVars(), SCIPisEQ(), SCIPisInfinity(), SCIPisPositive(), SCIPreallocBlockMemoryArray, SCIPvarGetProbindex(), SYM_SENSE_BOUNDIS_TYPE_2, SYM_SENSE_EQUATION, SYM_SENSE_INEQUALITY, SYM_SENSE_XOR, TRUE, and SYM_Sortrhstype::vals.

Referenced by computeSymmetryGroup().

◆ checkSymmetriesAreSymmetries()

static SCIP_RETCODE checkSymmetriesAreSymmetries ( SCIP scip,
SYM_SPEC  fixedtype,
SYM_MATRIXDATA matrixdata,
int  nperms,
int **  perms 
)
static

checks whether given permutations form a symmetry of a MIP

We need the matrix and rhs in the original order in order to speed up the comparison process. The matrix is needed in the right order to easily check rows. The rhs is used because of cache effects.

Parameters
scipSCIP data structure
fixedtypevariable types that must be fixed by symmetries
matrixdatamatrix data
npermsnumber of permutations
permspermutations

Definition at line 1067 of file prop_symmetry.c.

References FALSE, SYM_Matrixdata::matcoef, SYM_Matrixdata::matrhsidx, SYM_Matrixdata::matvaridx, SYM_Matrixdata::nmatcoef, SYM_Matrixdata::npermvars, SYM_Matrixdata::nrhscoef, SYM_Sortrhstype::nrhscoef, NULL, SYM_Matrixdata::permvars, SYM_Matrixdata::rhscoef, SYM_Matrixdata::rhssense, SCIP_Bool, SCIP_CALL, SCIP_ERROR, SCIP_OKAY, SCIP_Real, SCIPallocBlockMemoryArray, SCIPdebugMsg, SCIPerrorMessage, SCIPfreeBlockMemoryArray, SCIPisEQ(), SCIPisZero(), SymmetryFixVar(), and TRUE.

Referenced by computeSymmetryGroup().

◆ getNSymhandableConss()

static int getNSymhandableConss ( SCIP scip)
static

returns the number of active constraints that can be handled by symmetry

Parameters
scipSCIP instance

Definition at line 1213 of file prop_symmetry.c.

References NULL, SCIPconshdlrGetNActiveConss(), and SCIPfindConshdlr().

Referenced by computeSymmetryGroup(), and determineSymmetry().

◆ setSymmetryData()

static SCIP_RETCODE setSymmetryData ( SCIP scip,
SCIP_VAR **  vars,
int  nvars,
int  nbinvars,
SCIP_VAR ***  permvars,
int *  npermvars,
int *  nbinpermvars,
int **  perms,
int  nperms,
int *  nmovedvars,
SCIP_Bool binvaraffected,
SCIP_Bool  usecompression,
SCIP_Real  compressthreshold,
SCIP_Bool compressed 
)
static

set symmetry data

Parameters
scipSCIP pointer
varsvars present at time of symmetry computation
nvarsnumber of vars present at time of symmetry computation
nbinvarsnumber of binary vars present at time of symmetry computation
permvarspointer to permvars array
npermvarspointer to store number of permvars
nbinpermvarspointer to store number of binary permvars
permspermutations matrix (nperms x nvars)
npermsnumber of permutations
nmovedvarspointer to store number of vars affected by symmetry (if usecompression) or NULL
binvaraffectedpointer to store whether a binary variable is affected by symmetry
usecompressionwhether symmetry data shall be compressed
compressthresholdif percentage of moved vars is at most threshold, compression is done
compressedpointer to store whether compression has been performed

Definition at line 1249 of file prop_symmetry.c.

References COMPRESSNVARSLB, FALSE, NULL, SCIP_CALL, SCIP_OKAY, SCIP_Real, SCIPallocBlockMemoryArray, SCIPallocBufferArray, SCIPfreeBlockMemoryArray, SCIPfreeBufferArray, SCIPgetNVars(), SCIPisGE(), SCIPisLE(), SCIPreallocBlockMemoryArray, SCIPvarIsBinary(), and TRUE.

Referenced by computeSymmetryGroup().

◆ computeSymmetryGroup()

static SCIP_RETCODE computeSymmetryGroup ( SCIP scip,
SCIP_Bool  doubleequations,
SCIP_Bool  compresssymmetries,
SCIP_Real  compressthreshold,
int  maxgenerators,
SYM_SPEC  fixedtype,
SCIP_Bool  local,
SCIP_Bool  checksymmetries,
SCIP_Bool  usecolumnsparsity,
int *  npermvars,
int *  nbinpermvars,
SCIP_VAR ***  permvars,
int *  nperms,
int *  nmaxperms,
int ***  perms,
SCIP_Real log10groupsize,
int *  nmovedvars,
SCIP_Bool binvaraffected,
SCIP_Bool compressed,
SCIP_Bool success 
)
static

computes symmetry group of a MIP

Parameters
scipSCIP pointer
doubleequationsDouble equations to positive/negative version?
compresssymmetriesShould non-affected variables be removed from permutation to save memory?
compressthresholdCompression is used if percentage of moved vars is at most the threshold.
maxgeneratorsmaximal number of generators constructed (= 0 if unlimited)
fixedtypevariable types that must be fixed by symmetries
localUse local variable bounds?
checksymmetriesShould all symmetries be checked after computation?
usecolumnsparsityShould the number of conss a variable is contained in be exploited in symmetry detection?
npermvarspointer to store number of variables for permutations
nbinpermvarspointer to store number of binary variables for permutations
permvarspointer to store variables on which permutations act
npermspointer to store number of permutations
nmaxpermspointer to store maximal number of permutations (needed for freeing storage)
permspointer to store permutation generators as (nperms x npermvars) matrix
log10groupsizepointer to store log10 of size of group
nmovedvarspointer to store number of moved vars
binvaraffectedpointer to store wether a binary variable is affected by symmetry
compressedpointer to store whether compression has been performed
successpointer to store whether symmetry computation was successful

Definition at line 1380 of file prop_symmetry.c.

References checkSymmetriesAreSymmetries(), collectCoefficients(), SYM_Vartype::color, FALSE, getNSymhandableConss(), SYM_Vartype::lb, SYM_Matrixdata::matcoef, SYM_Matrixdata::matcoefcolors, SYM_Matrixdata::matidx, SYM_Matrixdata::matrhsidx, SYM_Matrixdata::matvaridx, MAX, SYM_Vartype::nconss, SYM_Matrixdata::nmatcoef, SYM_Matrixdata::nmaxmatcoef, SYM_Matrixdata::npermvars, SYM_Matrixdata::nrhscoef, SYM_Sortrhstype::nrhscoef, NULL, SYM_Matrixdata::nuniquemat, SYM_Matrixdata::nuniquerhs, SYM_Matrixdata::nuniquevars, SYM_Vartype::obj, SYM_Matrixdata::permvarcolors, SYM_Matrixdata::permvars, SYM_Matrixdata::rhscoef, SYM_Matrixdata::rhscoefcolors, SYM_Matrixdata::rhsidx, SYM_Matrixdata::rhssense, SCIP_Bool, SCIP_BOUNDTYPE_LOWER, SCIP_CALL, SCIP_ERROR, SCIP_INVALID, SCIP_Longint, SCIP_OKAY, SCIP_Real, SCIP_SETPPCTYPE_COVERING, SCIP_SETPPCTYPE_PACKING, SCIP_SETPPCTYPE_PARTITIONING, SCIP_SPECIALVAL, SCIP_STAGE_INITPRESOLVE, SCIP_STAGE_SOLVING, SCIP_VERBLEVEL_HIGH, SCIPallocBlockMemoryArray, SCIPallocClearBlockMemoryArray, SCIPblkmem(), SCIPconsGetHdlr(), SCIPconsGetName(), SCIPconshdlrGetName(), SCIPconsIsActive(), SCIPconsIsConflict(), SCIPconsIsTransformed(), SCIPdebugMsg, SCIPduplicateBlockMemoryArray, SCIPerrorMessage, SCIPfreeBlockMemoryArray, SCIPfreeBlockMemoryArrayNull, SCIPgetBinvarsLinking(), SCIPgetBoundsBounddisjunction(), SCIPgetBoundtypesBounddisjunction(), SCIPgetCapacityKnapsack(), SCIPgetConss(), SCIPgetIntVarXor(), SCIPgetLhsLinear(), SCIPgetLhsVarbound(), SCIPgetLinkvarLinking(), SCIPgetNActiveConss(), SCIPgetNBinVars(), SCIPgetNConss(), SCIPgetNFixedVars(), SCIPgetNVars(), SCIPgetNVarsAnd(), SCIPgetNVarsBounddisjunction(), SCIPgetNVarsKnapsack(), SCIPgetNVarsLinear(), SCIPgetNVarsLogicor(), SCIPgetNVarsOr(), SCIPgetNVarsSetppc(), SCIPgetNVarsXor(), SCIPgetResultantAnd(), SCIPgetResultantOr(), SCIPgetRhsLinear(), SCIPgetRhsVarbound(), SCIPgetRhsXor(), SCIPgetStage(), SCIPgetTypeSetppc(), SCIPgetValsLinear(), SCIPgetValsLinking(), SCIPgetVars(), SCIPgetVarsAnd(), SCIPgetVarsBounddisjunction(), SCIPgetVarsKnapsack(), SCIPgetVarsLinear(), SCIPgetVarsLogicor(), SCIPgetVarsOr(), SCIPgetVarsSetppc(), SCIPgetVarsXor(), SCIPgetVarVarbound(), SCIPgetVbdcoefVarbound(), SCIPgetVbdvarVarbound(), SCIPgetWeightsKnapsack(), SCIPhashtableCreate(), SCIPhashtableExists(), SCIPhashtableFree(), SCIPhashtableInsert(), SCIPhashtableRetrieve(), SCIPinfinity(), SCIPisEQ(), SCIPisStopped(), SCIPisZero(), SCIPsort(), SCIPvarGetLbGlobal(), SCIPvarGetLbLocal(), SCIPvarGetName(), SCIPvarGetObj(), SCIPvarGetProbindex(), SCIPvarGetType(), SCIPvarGetUbGlobal(), SCIPvarGetUbLocal(), SCIPverbMessage(), SYM_Sortrhstype::senses, setSymmetryData(), SYM_SENSE_AND, SYM_SENSE_BOUNDIS_TYPE_1, SYM_SENSE_BOUNDIS_TYPE_2, SYM_SENSE_EQUATION, SYM_SENSE_INEQUALITY, SYM_SENSE_OR, SYM_SENSE_UNKOWN, SYM_SENSE_XOR, SYMcanComputeSymmetry(), SYMcomputeSymmetryGenerators(), SymmetryFixVar(), TRUE, SYM_Vartype::type, SYM_Vartype::ub, and SYM_Sortrhstype::vals.

Referenced by determineSymmetry().

◆ determineSymmetry()

◆ detectOrbitopes()

static SCIP_RETCODE detectOrbitopes ( SCIP scip,
SCIP_PROPDATA propdata,
int *  components,
int *  componentbegins,
int  ncomponents 
)
static

checks whether components of the symmetry group can be completely handled by orbitopes

Parameters
scipSCIP instance
propdatapointer to data of symmetry propagator
componentsarray containing components of symmetry group
componentbeginsarray containing begin positions of components in components array
ncomponentsnumber of components

Definition at line 2491 of file prop_symmetry.c.

References FALSE, NULL, SCIP_Bool, SCIP_CALL, SCIP_OKAY, SCIP_ORBITOPETYPE_FULL, SCIPaddCons(), SCIPallocBufferArray, SCIPallocClearBufferArray, SCIPcreateConsOrbitope(), SCIPextendSubOrbitope(), SCIPfreeBufferArray, SCIPgenerateOrbitopeVarsMatrix(), SCIPgetPropertiesPerm(), and TRUE.

Referenced by tryAddSymmetryHandlingConss().

◆ addSymresackConss()

static SCIP_RETCODE addSymresackConss ( SCIP scip,
SCIP_PROP prop,
int *  components,
int *  componentbegins,
int  ncomponents 
)
static

adds symresack constraints

Parameters
scipSCIP instance
propsymmetry breaking propagator
componentsarray containing components of symmetry group
componentbeginsarray containing begin positions of components in components array
ncomponentsnumber of components

Definition at line 2758 of file prop_symmetry.c.

References FALSE, NULL, SCIP_Bool, SCIP_CALL, SCIP_MAXSTRLEN, SCIP_OKAY, SCIPaddCons(), SCIPcreateSymbreakCons(), SCIPdebugMsg, SCIPpropGetData(), SCIPsnprintf(), and TRUE.

Referenced by tryAddSymmetryHandlingConss().

◆ tryAddSymmetryHandlingConss()

static SCIP_RETCODE tryAddSymmetryHandlingConss ( SCIP scip,
SCIP_PROP prop,
SCIP_Bool earlyterm 
)
static

finds problem symmetries

Parameters
scipSCIP instance
propsymmetry breaking propagator
earlytermpointer to store whether we terminated early (or NULL)

Definition at line 2863 of file prop_symmetry.c.

References addSymresackConss(), detectOrbitopes(), determineSymmetry(), FALSE, NULL, SCIP_CALL, SCIP_OKAY, SCIPallocBlockMemoryArray, SCIPisStopped(), SCIPpropGetData(), SYM_SPEC_BINARY, SYM_SPEC_INTEGER, SYM_SPEC_REAL, and TRUE.

Referenced by SCIP_DECL_PROPEXITPRE(), SCIP_DECL_PROPINITPRE(), and SCIP_DECL_PROPPRESOL().

◆ performOrbitalFixing()

static SCIP_RETCODE performOrbitalFixing ( SCIP scip,
SCIP_VAR **  permvars,
int  npermvars,
int *  orbits,
int *  orbitbegins,
int  norbits,
SCIP_Bool infeasible,
int *  nfixedzero,
int *  nfixedone 
)
static

performs orbital fixing

Note that we do not have to distinguish between variables that have been fixed or branched to 1, since the stabilizer is with respect to the variables that have been branched to 1. Thus, if an orbit contains a variable that has been branched to 1, the whole orbit only contains variables that have been branched to 1 - and nothing can be fixed.

Parameters
scipSCIP pointer
permvarsvariables
npermvarsnumber of variables
orbitsarray of non-trivial orbits
orbitbeginsarray containing begin positions of new orbits in orbits array
norbitsnumber of orbits
infeasiblepointer to store whether problem is infeasible
nfixedzeropointer to store number of variables fixed to 0
nfixedonepointer to store number of variables fixed to 1

Definition at line 2960 of file prop_symmetry.c.

References FALSE, NULL, SCIP_Bool, SCIP_CALL, SCIP_OKAY, SCIP_VARTYPE_BINARY, SCIPdebugMsg, SCIPtightenVarLb(), SCIPtightenVarUb(), SCIPvarGetLbLocal(), SCIPvarGetName(), SCIPvarGetType(), SCIPvarGetUbLocal(), and TRUE.

Referenced by propagateOrbitalFixing().

◆ computeBranchingVariables()

static SCIP_RETCODE computeBranchingVariables ( SCIP scip,
int  nvars,
SCIP_HASHMAP varmap,
SCIP_Shortbool bg1,
int *  bg1list,
int *  nbg1 
)
static

Gets branching variables on the path to root

The variables are added to bg1 and bg1list, which are prefilled with the variables globally fixed to 1.

Parameters
scipSCIP pointer
nvarsnumber of variables
varmapmap of variables to indices in vars array
bg1bitset marking the variables globally fixed or branched to 1
bg1listarray to store the variable indices globally fixed or branched to 1
nbg1pointer to store the number of variables in bg1 and bg1list

Definition at line 3098 of file prop_symmetry.c.

References NULL, SCIP_BOUNDCHGTYPE_BRANCHING, SCIP_CALL, SCIP_OKAY, SCIP_VARTYPE_BINARY, SCIPboundchgGetBoundchgtype(), SCIPboundchgGetVar(), SCIPdomchgGetBoundchg(), SCIPdomchgGetNBoundchgs(), SCIPgetCurrentNode(), SCIPhashmapExists(), SCIPhashmapGetImageInt(), SCIPnodeGetDepth(), SCIPnodeGetDomchg(), SCIPnodeGetParent(), SCIPprintNodeRootPath(), SCIPvarGetLbLocal(), SCIPvarGetType(), and TRUE.

Referenced by propagateOrbitalFixing().

◆ propagateOrbitalFixing()

static SCIP_RETCODE propagateOrbitalFixing ( SCIP scip,
SCIP_PROPDATA propdata,
SCIP_Bool infeasible,
int *  nprop 
)
static

propagates orbital fixing

Parameters
scipSCIP pointer
propdatadata of symmetry breaking propagator
infeasiblepointer to store whether the node is detected to be infeasible
nproppointer to store the number of propagations

Definition at line 3190 of file prop_symmetry.c.

References computeBranchingVariables(), determineSymmetry(), FALSE, NULL, performOrbitalFixing(), SCIP_CALL, SCIP_OKAY, SCIP_Shortbool, SCIP_VARTYPE_CONTINUOUS, SCIP_VARTYPE_IMPLINT, SCIPallocBufferArray, SCIPcomputeOrbitsFilterSym(), SCIPdebugMsg, SCIPfreeBufferArray, SCIPisEQ(), SCIPvarGetLbGlobal(), SCIPvarGetType(), SCIPvarGetUbGlobal(), SCIPvarIsBinary(), SYM_SPEC_BINARY, SYM_SPEC_INTEGER, SYM_SPEC_REAL, and TRUE.

Referenced by SCIP_DECL_PROPEXEC(), and SCIP_DECL_PROPPRESOL().

◆ SCIP_DECL_PROPINITPRE()

static SCIP_DECL_PROPINITPRE ( propInitpreSymmetry  )
static

presolving initialization method of propagator (called when presolving is about to begin)

Definition at line 3458 of file prop_symmetry.c.

References FALSE, ISORBITALFIXINGACTIVE, ISSYMRETOPESACTIVE, NULL, SCIP_CALL, SCIP_OKAY, SCIPdebugMsg, SCIPgetIntParam(), SCIPpropGetData(), TRUE, and tryAddSymmetryHandlingConss().

◆ SCIP_DECL_PROPEXITPRE()

static SCIP_DECL_PROPEXITPRE ( propExitpreSymmetry  )
static

presolving deinitialization method of propagator (called after presolving has been finished)

Definition at line 3498 of file prop_symmetry.c.

References NULL, PROP_NAME, SCIP_CALL, SCIP_OKAY, SCIP_STATUS_UNKNOWN, SCIPdebugMsg, SCIPgetStatus(), SCIPpropGetData(), SCIPpropGetName(), and tryAddSymmetryHandlingConss().

◆ SCIP_DECL_PROPPRESOL()

◆ SCIP_DECL_PROPEXEC()

◆ SCIP_DECL_PROPEXIT()

static SCIP_DECL_PROPEXIT ( propExitSymmetry  )
static

deinitialization method of propagator (called before transformed problem is freed)

Definition at line 3725 of file prop_symmetry.c.

References FALSE, freeSymmetryData(), NULL, PROP_NAME, SCIP_CALL, SCIP_OKAY, SCIPdebugMsg, SCIPpropGetData(), and SCIPpropGetName().

◆ SCIP_DECL_PROPRESPROP()

static SCIP_DECL_PROPRESPROP ( propRespropSymmetry  )
static

propagation conflict resolving method of propagator

Note that this is relatively difficult to obtain: One needs to include all bounds of variables that are responsible for creating the orbit in which the variables that was propagated lies. This includes all variables that are moved by the permutations which are involved in creating the orbit.

Definition at line 3766 of file prop_symmetry.c.

References NULL, SCIP_DIDNOTFIND, and SCIP_OKAY.

◆ SCIP_DECL_PROPFREE()

static SCIP_DECL_PROPFREE ( propFreeSymmetry  )
static

destructor of propagator to free user data (called when SCIP is exiting)

Definition at line 3778 of file prop_symmetry.c.

References NULL, PROP_NAME, SCIP_OKAY, SCIPdebugMsg, SCIPfreeBlockMemory, SCIPpropGetData(), and SCIPpropGetName().

◆ SCIPincludePropSymmetry()

◆ SCIPgetSymmetry()

SCIP_RETCODE SCIPgetSymmetry ( SCIP scip,
int *  npermvars,
SCIP_VAR ***  permvars,
SCIP_HASHMAP **  permvarmap,
int *  nperms,
int ***  perms,
int ***  permstrans,
SCIP_Real log10groupsize,
SCIP_Bool binvaraffected,
int **  components,
int **  componentbegins,
int **  vartocomponent,
int *  ncomponents 
)

return currently available symmetry group information

Parameters
scipSCIP data structure
npermvarspointer to store number of variables for permutations
permvarspointer to store variables on which permutations act
permvarmappointer to store hash map of permvars (or NULL)
npermspointer to store number of permutations
permspointer to store permutation generators as (nperms x npermvars) matrix (or NULL)
permstranspointer to store permutation generators as (npermvars x nperms) matrix (or NULL)
log10groupsizepointer to store log10 of group size (or NULL)
binvaraffectedpointer to store whether binary variables are affected
componentspointer to store components of symmetry group (or NULL)
componentbeginspointer to store begin positions of components in components array (or NULL)
vartocomponentpointer to store assignment from variable to its component (or NULL)
ncomponentspointer to store number of components (or NULL)

Definition at line 3979 of file prop_symmetry.c.

References NULL, PROP_NAME, SCIP_OKAY, SCIP_PLUGINNOTFOUND, SCIPerrorMessage, SCIPfindProp(), SCIPpropGetData(), and SCIPpropGetName().

Referenced by initOrbits().

◆ SCIPisOrbitalfixingEnabled()

SCIP_Bool SCIPisOrbitalfixingEnabled ( SCIP scip)

return whether orbital fixing is enabled

Parameters
scipSCIP data structure

Definition at line 4059 of file prop_symmetry.c.

References FALSE, NULL, PROP_NAME, SCIPfindProp(), and SCIPpropGetData().

Referenced by isRestartApplicable().

◆ SCIPgetSymmetryNGenerators()

int SCIPgetSymmetryNGenerators ( SCIP scip)

return number of the symmetry group's generators

Parameters
scipSCIP data structure

Definition at line 4079 of file prop_symmetry.c.

References NULL, PROP_NAME, SCIPfindProp(), and SCIPpropGetData().

Referenced by isRestartApplicable().