SCIP
Solving Constraint Integer Programs
Solving Constraint Integer Programs
Constraint handler for "xor" constraints, \(rhs = x_1 \oplus x_2 \oplus \dots \oplus x_n\).
This constraint handler deals with "xor" constraint. These are constraint of the form:
\[ rhs = x_1 \oplus x_2 \oplus \dots \oplus x_n \]
where \(x_i\) is a binary variable for all \(i\) and \(rhs\) is bool. The variables \(x\)'s are called operators. This constraint is satisfied if \(rhs\) is TRUE and an odd number of the operators are TRUE or if the \(rhs\) is FALSE and a even number of operators are TRUE. Hence, if the sum of \(rhs\) and operators is even.
Definition in file cons_xor.c.
#include <assert.h>#include <string.h>#include "scip/pub_misc.h"#include "scip/cons_xor.h"#include "scip/cons_setppc.h"#include "scip/cons_linear.h"#include "scip/heur_trysol.h"#include "scip/debug.h"Go to the source code of this file.
Typedefs | |
| typedef unsigned short | Type |
| typedef enum Proprule | PROPRULE |
Enumerations | |
| enum | Proprule { PROPRULE_1, PROPRULE_2, PROPRULE_3, PROPRULE_4, PROPRULE_INVALID, PROPRULE_INVALID = 0, PROPRULE_1 = 1, PROPRULE_2 = 2, PROPRULE_3 = 3, PROPRULE_4 = 4, PROPRULE_1_CORETIMES = 1, PROPRULE_2_EDGEFINDING = 2, PROPRULE_3_TTEF = 3, PROPRULE_1_RHS = 1, PROPRULE_1_LHS = 2, PROPRULE_1_RANGEDROW = 3, PROPRULE_INVALID = 0, PROPRULE_1, PROPRULE_2, PROPRULE_3, PROPRULE_4, PROPRULE_INVALID, PROPRULE_1, PROPRULE_2, PROPRULE_3, PROPRULE_4, PROPRULE_0, PROPRULE_1, PROPRULE_INTLB, PROPRULE_INTUB, PROPRULE_INVALID } |
Functions | |
| static SCIP_RETCODE | lockRounding (SCIP *scip, SCIP_CONS *cons, SCIP_VAR *var) |
| static SCIP_RETCODE | unlockRounding (SCIP *scip, SCIP_CONS *cons, SCIP_VAR *var) |
| static SCIP_RETCODE | conshdlrdataCreate (SCIP *scip, SCIP_CONSHDLRDATA **conshdlrdata, SCIP_EVENTHDLR *eventhdlr) |
| static SCIP_RETCODE | conshdlrdataFree (SCIP *scip, SCIP_CONSHDLRDATA **conshdlrdata) |
| static SCIP_RETCODE | consdataSwitchWatchedvars (SCIP *scip, SCIP_CONSDATA *consdata, SCIP_EVENTHDLR *eventhdlr, int watchedvar1, int watchedvar2) |
| static SCIP_RETCODE | consdataEnsureVarsSize (SCIP *scip, SCIP_CONSDATA *consdata, int num) |
| static SCIP_RETCODE | consdataCreate (SCIP *scip, SCIP_CONSDATA **consdata, SCIP_Bool rhs, int nvars, SCIP_VAR **vars, SCIP_VAR *intvar) |
| static SCIP_RETCODE | consdataFreeRows (SCIP *scip, SCIP_CONSDATA *consdata) |
| static SCIP_RETCODE | consdataFree (SCIP *scip, SCIP_CONSDATA **consdata, SCIP_EVENTHDLR *eventhdlr) |
| static SCIP_RETCODE | consdataPrint (SCIP *scip, SCIP_CONSDATA *consdata, FILE *file, SCIP_Bool endline) |
| static SCIP_RETCODE | setIntvar (SCIP *scip, SCIP_CONS *cons, SCIP_VAR *var) |
| static SCIP_RETCODE | addCoef (SCIP *scip, SCIP_CONS *cons, SCIP_VAR *var) |
| static SCIP_RETCODE | delCoefPos (SCIP *scip, SCIP_CONS *cons, SCIP_EVENTHDLR *eventhdlr, int pos) |
| static void | consdataSort (SCIP_CONSDATA *consdata) |
| static | SCIP_DECL_HASHGETKEY (hashGetKeyXorcons) |
| static | SCIP_DECL_HASHKEYEQ (hashKeyEqXorcons) |
| static | SCIP_DECL_HASHKEYVAL (hashKeyValXorcons) |
| static SCIP_RETCODE | applyFixings (SCIP *scip, SCIP_CONS *cons, SCIP_EVENTHDLR *eventhdlr, int *nchgcoefs, int *naggrvars, int *naddconss, SCIP_Bool *cutoff) |
| static SCIP_RETCODE | addExtendedFlowFormulation (SCIP *scip, SCIP_CONS *cons, int *naddedconss) |
| static SCIP_RETCODE | addExtendedAsymmetricFormulation (SCIP *scip, SCIP_CONS *cons, int *naddedconss) |
| static SCIP_RETCODE | createRelaxation (SCIP *scip, SCIP_CONS *cons) |
| static SCIP_RETCODE | addRelaxation (SCIP *scip, SCIP_CONS *cons, SCIP_Bool *infeasible) |
| static SCIP_Bool | allRowsInLP (SCIP_CONSDATA *consdata) |
| static SCIP_RETCODE | checkCons (SCIP *scip, SCIP_CONS *cons, SCIP_SOL *sol, SCIP_Bool checklprows, SCIP_Bool *violated) |
| static SCIP_RETCODE | separateCons (SCIP *scip, SCIP_CONS *cons, SCIP_SOL *sol, SCIP_Bool separateparity, SCIP_Bool *separated, SCIP_Bool *cutoff) |
| static int | computeRowEcholonGF2 (SCIP *scip, int m, int n, int *p, int *s, Type **A, Type *b) |
| static void | solveRowEcholonGF2 (int m, int n, int r, int *p, int *s, Type **A, Type *b, Type *x) |
| static SCIP_RETCODE | checkSystemGF2 (SCIP *scip, SCIP_CONS **conss, int nconss, SCIP_SOL *currentsol, SCIP_RESULT *result) |
| static SCIP_RETCODE | addConflictBounds (SCIP *scip, SCIP_CONS *cons, SCIP_VAR *infervar, SCIP_BDCHGIDX *bdchgidx, PROPRULE proprule) |
| static SCIP_RETCODE | analyzeConflict (SCIP *scip, SCIP_CONS *cons, SCIP_VAR *infervar, PROPRULE proprule) |
| static SCIP_RETCODE | propagateCons (SCIP *scip, SCIP_CONS *cons, SCIP_EVENTHDLR *eventhdlr, SCIP_Bool *cutoff, int *nfixedvars, int *nchgbds) |
| static SCIP_RETCODE | resolvePropagation (SCIP *scip, SCIP_CONS *cons, SCIP_VAR *infervar, PROPRULE proprule, SCIP_BDCHGIDX *bdchgidx, SCIP_RESULT *result) |
| static SCIP_RETCODE | cliquePresolve (SCIP *scip, SCIP_CONS *cons, int *nfixedvars, int *nchgcoefs, int *ndelconss, int *naddconss, SCIP_Bool *cutoff) |
| static SCIP_RETCODE | detectRedundantConstraints (SCIP *scip, BMS_BLKMEM *blkmem, SCIP_CONS **conss, int nconss, int *firstchange, int *nchgcoefs, int *naggrvars, int *ndelconss, int *naddconss, SCIP_Bool *cutoff) |
| static SCIP_RETCODE | preprocessConstraintPairs (SCIP *scip, SCIP_CONS **conss, int firstchange, int chkind, SCIP_Bool *cutoff, int *nfixedvars, int *naggrvars, int *ndelconss, int *naddconss, int *nchgcoefs) |
| static SCIP_RETCODE | createConsXorIntvar (SCIP *scip, SCIP_CONS **cons, const char *name, SCIP_Bool rhs, int nvars, SCIP_VAR **vars, SCIP_VAR *intvar, SCIP_Bool initial, SCIP_Bool separate, SCIP_Bool enforce, SCIP_Bool check, SCIP_Bool propagate, SCIP_Bool local, SCIP_Bool modifiable, SCIP_Bool dynamic, SCIP_Bool removable, SCIP_Bool stickingatnode) |
| static | SCIP_DECL_LINCONSUPGD (linconsUpgdXor) |
| static | SCIP_DECL_CONSHDLRCOPY (conshdlrCopyXor) |
| static | SCIP_DECL_CONSFREE (consFreeXor) |
| static | SCIP_DECL_CONSEXITSOL (consExitsolXor) |
| static | SCIP_DECL_CONSDELETE (consDeleteXor) |
| static | SCIP_DECL_CONSTRANS (consTransXor) |
| static | SCIP_DECL_CONSINITLP (consInitlpXor) |
| static | SCIP_DECL_CONSSEPALP (consSepalpXor) |
| static | SCIP_DECL_CONSSEPASOL (consSepasolXor) |
| static | SCIP_DECL_CONSENFOLP (consEnfolpXor) |
| static | SCIP_DECL_CONSENFORELAX (consEnforelaxXor) |
| static | SCIP_DECL_CONSENFOPS (consEnfopsXor) |
| static | SCIP_DECL_CONSCHECK (consCheckXor) |
| static | SCIP_DECL_CONSPROP (consPropXor) |
| static | SCIP_DECL_CONSINITPRE (consInitpreXor) |
| static | SCIP_DECL_CONSEXITPRE (consExitpreXor) |
| static | SCIP_DECL_CONSPRESOL (consPresolXor) |
| static | SCIP_DECL_CONSRESPROP (consRespropXor) |
| static | SCIP_DECL_CONSLOCK (consLockXor) |
| static | SCIP_DECL_CONSPRINT (consPrintXor) |
| static | SCIP_DECL_CONSCOPY (consCopyXor) |
| static | SCIP_DECL_CONSPARSE (consParseXor) |
| static | SCIP_DECL_CONSGETVARS (consGetVarsXor) |
| static | SCIP_DECL_CONSGETNVARS (consGetNVarsXor) |
| static | SCIP_DECL_EVENTEXEC (eventExecXor) |
| SCIP_RETCODE | SCIPincludeConshdlrXor (SCIP *scip) |
| SCIP_RETCODE | SCIPcreateConsXor (SCIP *scip, SCIP_CONS **cons, const char *name, SCIP_Bool rhs, int nvars, SCIP_VAR **vars, SCIP_Bool initial, SCIP_Bool separate, SCIP_Bool enforce, SCIP_Bool check, SCIP_Bool propagate, SCIP_Bool local, SCIP_Bool modifiable, SCIP_Bool dynamic, SCIP_Bool removable, SCIP_Bool stickingatnode) |
| SCIP_RETCODE | SCIPcreateConsBasicXor (SCIP *scip, SCIP_CONS **cons, const char *name, SCIP_Bool rhs, int nvars, SCIP_VAR **vars) |
| int | SCIPgetNVarsXor (SCIP *scip, SCIP_CONS *cons) |
| SCIP_VAR ** | SCIPgetVarsXor (SCIP *scip, SCIP_CONS *cons) |
| SCIP_VAR * | SCIPgetIntVarXor (SCIP *scip, SCIP_CONS *cons) |
| SCIP_Bool | SCIPgetRhsXor (SCIP *scip, SCIP_CONS *cons) |
| #define CONSHDLR_NAME "xor" |
Definition at line 48 of file cons_xor.c.
Referenced by addCoef(), consdataCreate(), createConsXorIntvar(), SCIP_DECL_CONSHDLRCOPY(), SCIPcreateConsXor(), SCIPgetIntVarXor(), SCIPgetNVarsXor(), SCIPgetRhsXor(), SCIPgetVarsXor(), and SCIPincludeConshdlrXor().
| #define CONSHDLR_DESC "constraint handler for xor constraints: r = xor(x1, ..., xn)" |
Definition at line 49 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define CONSHDLR_SEPAPRIORITY +850200 |
priority of the constraint handler for separation
Definition at line 50 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define CONSHDLR_ENFOPRIORITY -850200 |
priority of the constraint handler for constraint enforcing
Definition at line 51 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define CONSHDLR_CHECKPRIORITY -850200 |
priority of the constraint handler for checking feasibility
Definition at line 52 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define CONSHDLR_SEPAFREQ 0 |
frequency for separating cuts; zero means to separate only in the root node
Definition at line 53 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define CONSHDLR_PROPFREQ 1 |
frequency for propagating domains; zero means only preprocessing propagation
Definition at line 54 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define CONSHDLR_EAGERFREQ 100 |
frequency for using all instead of only the useful constraints in separation, propagation and enforcement, -1 for no eager evaluations, 0 for first only
Definition at line 55 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define CONSHDLR_MAXPREROUNDS -1 |
maximal number of presolving rounds the constraint handler participates in (-1: no limit)
Definition at line 58 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define CONSHDLR_DELAYSEPA FALSE |
should separation method be delayed, if other separators found cuts?
Definition at line 59 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define CONSHDLR_DELAYPROP FALSE |
should propagation method be delayed, if other propagators found reductions?
Definition at line 60 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define CONSHDLR_NEEDSCONS TRUE |
should the constraint handler be skipped, if no constraints are available?
Definition at line 61 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define CONSHDLR_PROP_TIMING SCIP_PROPTIMING_BEFORELP |
Definition at line 63 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define CONSHDLR_PRESOLTIMING SCIP_PRESOLTIMING_ALWAYS |
Definition at line 64 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define EVENTHDLR_NAME "xor" |
Definition at line 66 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define EVENTHDLR_DESC "event handler for xor constraints" |
Definition at line 67 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define LINCONSUPGD_PRIORITY +600000 |
priority of the constraint handler for upgrading of linear constraints
Definition at line 69 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define DEFAULT_PRESOLPAIRWISE TRUE |
should pairwise constraint comparison be performed in presolving?
Definition at line 71 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define DEFAULT_ADDEXTENDEDFORM FALSE |
should the extended formulation be added in presolving?
Definition at line 72 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define DEFAULT_ADDFLOWEXTENDED FALSE |
should the extended flow formulation be added (nonsymmetric formulation otherwise)?
Definition at line 73 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define DEFAULT_SEPARATEPARITY FALSE |
should parity inequalities be separated?
Definition at line 74 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define DEFAULT_GAUSSPROPFREQ 5 |
frequency for applying the Gauss propagator
Definition at line 75 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define HASHSIZE_XORCONS 500 |
minimal size of hash table in logicor constraint tables
Definition at line 76 of file cons_xor.c.
Referenced by detectRedundantConstraints().
| #define DEFAULT_PRESOLUSEHASHING TRUE |
should hash table be used for detecting redundant constraints in advance
Definition at line 77 of file cons_xor.c.
Referenced by SCIPincludeConshdlrXor().
| #define NMINCOMPARISONS 200000 |
number for minimal pairwise presolving comparisons
Definition at line 78 of file cons_xor.c.
Referenced by SCIP_DECL_CONSPRESOL().
| #define MINGAINPERNMINCOMPARISONS 1e-06 |
minimal gain per minimal pairwise presolving comparisons to repeat pairwise comparison round
Definition at line 79 of file cons_xor.c.
Referenced by SCIP_DECL_CONSPRESOL().
| #define MAXXORCONSSSYSTEM 1000 |
maximal number of active constraints for which checking the system over GF2 is performed
Definition at line 80 of file cons_xor.c.
Referenced by checkSystemGF2().
| #define MAXXORVARSSYSTEM 1000 |
maximal number of variables in xor constraints for which checking the system over GF2 is performed
Definition at line 81 of file cons_xor.c.
Referenced by checkSystemGF2().
| #define NROWS 5 |
Definition at line 83 of file cons_xor.c.
Referenced by addRelaxation(), allRowsInLP(), consdataCreate(), consdataFreeRows(), and separateCons().
| typedef unsigned short Type |
type used for matrix entries in function checkGauss()
Definition at line 91 of file cons_xor.c.
Definition at line 140 of file cons_xor.c.
| enum Proprule |
Definition at line 132 of file cons_xor.c.
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static |
installs rounding locks for the given variable in the given xor constraint
| scip | SCIP data structure |
| cons | xor constraint |
| var | variable of constraint entry |
Definition at line 149 of file cons_xor.c.
References SCIP_CALL, SCIP_OKAY, SCIPlockVarCons(), TRUE, and unlockRounding().
Referenced by addCoef(), createRelaxation(), and setIntvar().
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removes rounding locks for the given variable in the given xor constraint
| scip | SCIP data structure |
| cons | xor constraint |
| var | variable of constraint entry |
Definition at line 163 of file cons_xor.c.
References conshdlrdataCreate(), SCIP_CALL, SCIP_OKAY, SCIPunlockVarCons(), and TRUE.
Referenced by delCoefPos(), lockRounding(), and setIntvar().
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static |
creates constraint handler data
| scip | SCIP data structure |
| conshdlrdata | pointer to store the constraint handler data |
| eventhdlr | event handler |
Definition at line 177 of file cons_xor.c.
References conshdlrdataFree(), SCIP_CALL, SCIP_OKAY, and SCIPallocBlockMemory.
Referenced by SCIPincludeConshdlrXor(), and unlockRounding().
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static |
frees constraint handler data
| scip | SCIP data structure |
| conshdlrdata | pointer to the constraint handler data |
Definition at line 197 of file cons_xor.c.
References consdataSwitchWatchedvars(), SCIP_OKAY, and SCIPfreeBlockMemory.
Referenced by conshdlrdataCreate(), and SCIP_DECL_CONSFREE().
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static |
stores the given variable numbers as watched variables, and updates the event processing
| scip | SCIP data structure |
| consdata | xor constraint data |
| eventhdlr | event handler to call for the event processing |
| watchedvar1 | new first watched variable |
| watchedvar2 | new second watched variable |
Definition at line 212 of file cons_xor.c.
References consdataEnsureVarsSize(), SCIP_CALL, SCIP_EVENTTYPE_BOUNDCHANGED, SCIP_OKAY, SCIPcatchVarEvent(), and SCIPdropVarEvent().
Referenced by consdataFree(), conshdlrdataFree(), delCoefPos(), and propagateCons().
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static |
ensures, that the vars array can store at least num entries
| scip | SCIP data structure |
| consdata | linear constraint data |
| num | minimum number of entries to store |
Definition at line 276 of file cons_xor.c.
References consdataCreate(), SCIP_CALL, SCIP_OKAY, SCIPcalcMemGrowSize(), and SCIPreallocBlockMemoryArray.
Referenced by addCoef(), and consdataSwitchWatchedvars().
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static |
creates constraint data for xor constraint
| scip | SCIP data structure |
| consdata | pointer to store the constraint data |
| rhs | right hand side of the constraint |
| nvars | number of variables in the xor operation |
| vars | variables in xor operation |
| intvar | artificial integer variable for linear relaxation |
Definition at line 300 of file cons_xor.c.
References consdataFreeRows(), CONSHDLR_NAME, FALSE, NROWS, SCIP_CALL, SCIP_EVENTTYPE_VARFIXED, SCIP_OKAY, SCIP_STAGE_PRESOLVING, SCIPallocBlockMemory, SCIPcaptureVar(), SCIPcatchVarEvent(), SCIPconshdlrGetData(), SCIPduplicateBlockMemoryArray, SCIPfindConshdlr(), SCIPgetStage(), SCIPgetTransformedVar(), SCIPgetTransformedVars(), SCIPisTransformed(), and TRUE.
Referenced by consdataEnsureVarsSize(), createConsXorIntvar(), SCIP_DECL_CONSTRANS(), and SCIPcreateConsXor().
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releases LP row of constraint data
| scip | SCIP data structure |
| consdata | constraint data |
Definition at line 375 of file cons_xor.c.
References consdataFree(), NROWS, SCIP_CALL, SCIP_OKAY, and SCIPreleaseRow().
Referenced by consdataCreate(), consdataFree(), and SCIP_DECL_CONSEXITSOL().
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frees constraint data for xor constraint
| scip | SCIP data structure |
| consdata | pointer to the constraint data |
| eventhdlr | event handler to call for the event processing |
Definition at line 397 of file cons_xor.c.
References consdataFreeRows(), consdataPrint(), consdataSwitchWatchedvars(), SCIP_CALL, SCIP_OKAY, SCIPfreeBlockMemory, SCIPfreeBlockMemoryArray, SCIPisEQ(), SCIPisTransformed(), SCIPreleaseVar(), and SCIPvarGetLbGlobal().
Referenced by consdataFreeRows(), and SCIP_DECL_CONSDELETE().
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static |
prints xor constraint to file stream
| scip | SCIP data structure |
| consdata | xor constraint data |
| file | output file (or NULL for standard output) |
| endline | should an endline be set? |
Definition at line 458 of file cons_xor.c.
References SCIP_CALL, SCIP_OKAY, SCIPinfoMessage(), SCIPwriteVarName(), SCIPwriteVarsList(), setIntvar(), and TRUE.
Referenced by applyFixings(), consdataFree(), and SCIP_DECL_CONSPRINT().
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static |
sets intvar of an xor constraint
| scip | SCIP data structure |
| cons | xor constraint |
| var | variable to add to the constraint |
Definition at line 492 of file cons_xor.c.
References addCoef(), lockRounding(), SCIP_Bool, SCIP_CALL, SCIP_INVALIDCALL, SCIP_OKAY, SCIPcaptureVar(), SCIPconsGetData(), SCIPconsIsTransformed(), SCIPerrorMessage, SCIPgetTransformedVar(), SCIPreleaseVar(), SCIPvarIsTransformed(), TRUE, and unlockRounding().
Referenced by applyFixings(), consdataPrint(), and preprocessConstraintPairs().
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adds coefficient to xor constraint
| scip | SCIP data structure |
| cons | xor constraint |
| var | variable to add to the constraint |
Definition at line 544 of file cons_xor.c.
References consdataEnsureVarsSize(), CONSHDLR_NAME, delCoefPos(), lockRounding(), SCIP_Bool, SCIP_CALL, SCIP_EVENTTYPE_VARFIXED, SCIP_INVALIDCALL, SCIP_OKAY, SCIP_STAGE_EXITPRESOLVE, SCIP_STAGE_INITPRESOLVE, SCIP_STAGE_PRESOLVING, SCIPcatchVarEvent(), SCIPconsGetData(), SCIPconshdlrGetData(), SCIPconsIsTransformed(), SCIPerrorMessage, SCIPfindConshdlr(), SCIPgetStage(), SCIPgetTransformedVar(), SCIPvarIsTransformed(), and TRUE.
Referenced by applyFixings(), preprocessConstraintPairs(), and setIntvar().
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static |
deletes coefficient at given position from xor constraint data
| scip | SCIP data structure |
| cons | xor constraint |
| eventhdlr | event handler to call for the event processing |
| pos | position of coefficient to delete |
Definition at line 610 of file cons_xor.c.
References consdataSort(), consdataSwitchWatchedvars(), FALSE, SCIP_CALL, SCIP_EVENTTYPE_VARFIXED, SCIP_OKAY, SCIP_STAGE_EXITPRESOLVE, SCIP_STAGE_INITPRESOLVE, SCIP_STAGE_PRESOLVING, SCIPconsGetData(), SCIPconsIsTransformed(), SCIPdropVarEvent(), SCIPgetStage(), SCIPvarIsTransformed(), TRUE, and unlockRounding().
Referenced by addCoef(), and applyFixings().
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sorts and constraint's variables by non-decreasing variable index
| consdata | constraint data |
Definition at line 671 of file cons_xor.c.
References SCIP_DECL_HASHGETKEY(), SCIPsortPtr(), SCIPvarCompareActiveAndNegated(), and TRUE.
Referenced by applyFixings(), delCoefPos(), detectRedundantConstraints(), preprocessConstraintPairs(), and SCIP_DECL_HASHKEYEQ().
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gets the key of the given element
Definition at line 755 of file cons_xor.c.
References SCIP_DECL_HASHKEYEQ().
Referenced by consdataSort().
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returns TRUE iff both keys are equal; two constraints are equal if they have the same variables
Definition at line 763 of file cons_xor.c.
References consdataSort(), FALSE, SCIP_DECL_HASHKEYVAL(), SCIPconsGetData(), SCIPvarCompare(), SCIPvarCompareActiveAndNegated(), and TRUE.
Referenced by SCIP_DECL_HASHGETKEY().
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returns the hash value of the key
Definition at line 805 of file cons_xor.c.
References applyFixings(), SCIP_VARSTATUS_FIXED, SCIP_VARSTATUS_NEGATED, SCIPcombineTwoInt, SCIPconsGetData(), SCIPhashTwo, SCIPvarGetIndex(), SCIPvarGetStatus(), and SCIPvarIsActive().
Referenced by SCIP_DECL_HASHKEYEQ().
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static |
deletes all fixed variables and all pairs of equal variables
| scip | SCIP data structure |
| cons | xor constraint |
| eventhdlr | event handler to call for the event processing |
| nchgcoefs | pointer to add up the number of changed coefficients |
| naggrvars | pointer to add up the number of aggregated variables |
| naddconss | pointer to add up the number of added constraints |
| cutoff | whether a cutoff has been detected |
Definition at line 838 of file cons_xor.c.
References addCoef(), addExtendedFlowFormulation(), consdataPrint(), consdataSort(), delCoefPos(), SCIP_Bool, SCIP_CALL, SCIP_MAXSTRLEN, SCIP_OKAY, SCIP_Real, SCIP_VARSTATUS_FIXED, SCIP_VARTYPE_BINARY, SCIPaddCons(), SCIPaddVar(), SCIPaggregateVars(), SCIPconsGetData(), SCIPconsGetName(), SCIPconsIsDynamic(), SCIPconsIsInitial(), SCIPconsIsLocal(), SCIPconsIsModifiable(), SCIPconsIsRemovable(), SCIPconsIsSeparated(), SCIPconsIsStickingAtNode(), SCIPcreateConsLinear(), SCIPcreateVar(), SCIPdebug, SCIPdebugMsg, SCIPdoNotAggr(), SCIPgetBinvarRepresentative(), SCIPisEQ(), SCIPreleaseCons(), SCIPreleaseVar(), SCIPsnprintf(), SCIPvarGetLbGlobal(), SCIPvarGetName(), SCIPvarGetNegatedVar(), SCIPvarGetNegationVar(), SCIPvarGetProbvar(), SCIPvarGetStatus(), SCIPvarGetType(), SCIPvarGetUbGlobal(), SCIPvarIsActive(), SCIPvarIsBinary(), SCIPvarIsInitial(), SCIPvarIsNegated(), SCIPvarIsRemovable(), setIntvar(), and TRUE.
Referenced by detectRedundantConstraints(), preprocessConstraintPairs(), SCIP_DECL_CONSPRESOL(), and SCIP_DECL_HASHKEYVAL().
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static |
adds extended flow formulation
The extended flow formulation is built as follows: Let \(x_1, \dots, x_k\) be the variables contained in the given XOR constraint. We construct a two layered flow network. The upper layer is called the north layer and the lower is called the south layer. For each \(x_i,\; i = 2, \ldots, k-1\), we add arcs that stay in the north and south layer (denoted by 'nn' and 'ss', respectively), as well as arcs that change the layers (denoted by 'ns' and 'sn'). For \(x_1\), we only add two arcs from the source to the two layers. The source is located on the north layer. For \(x_k\), we add two arcs connecting the two layers to the sink. Depending on the rhs of the constraint the sink is located on the north or south layer. A change in the layers corresponds to a parity change, i.e., the corresponding variable \(x_i\) is 1 (and 0 otherwise).
| scip | SCIP data structure |
| cons | constraint to check |
| naddedconss | number of added constraints |
Definition at line 1108 of file cons_xor.c.
References addExtendedAsymmetricFormulation(), FALSE, SCIP_Bool, SCIP_CALL, SCIP_MAXSTRLEN, SCIP_OKAY, SCIP_Real, SCIP_VARTYPE_IMPLINT, SCIPaddCons(), SCIPaddVar(), SCIPaggregateVars(), SCIPallocBlockMemoryArray, SCIPconsGetData(), SCIPconsGetName(), SCIPconsIsInitial(), SCIPconsIsModifiable(), SCIPconsIsRemovable(), SCIPcreateConsLinear(), SCIPcreateVar(), SCIPdebugMsg, SCIPdebugPrintCons, SCIPlockVarCons(), SCIPreleaseCons(), SCIPsnprintf(), SCIPvarIsTransformed(), and TRUE.
Referenced by applyFixings(), and SCIP_DECL_CONSPRESOL().
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adds extended asymmetric formulation
The extended asymmetric formulation is constructed as follows: Let \(x_1, \dots, x_k\) be the variables contained in the given XOR constraint. We introduce variables \(p_1, \ldots, p_k\) with the following constraints: \(p_1 = x_1\), \(p_k = 1\), and for \(i = 2, \ldots, k-1\):
\[ \begin{array}{ll} p_i & \leq p_{i-1} + x_i\\ p_i & \leq 2 - (p_{i-1} + x_i)\\ p_i & \geq p_{i-1} - x_i\\ p_i & \geq x_i - p_{i-1}. \end{array} \]
This formulation is described in
Robert D. Carr and Goran Konjevod
Polyhedral combinatorics
In Harvey Greenberg, editor, Tutorials on emerging methodologies and applications in Operations Research,
Chapter 2, pages (2-1)-(2-48). Springer, 2004.
| scip | SCIP data structure |
| cons | constraint to check |
| naddedconss | number of added constraints |
Definition at line 1413 of file cons_xor.c.
References createRelaxation(), FALSE, SCIP_Bool, SCIP_CALL, SCIP_MAXSTRLEN, SCIP_OKAY, SCIP_Real, SCIP_VARTYPE_IMPLINT, SCIPaddCons(), SCIPaddVar(), SCIPaggregateVars(), SCIPallocBlockMemoryArray, SCIPconsGetData(), SCIPconsGetName(), SCIPconsIsInitial(), SCIPconsIsModifiable(), SCIPconsIsRemovable(), SCIPcreateConsLinear(), SCIPcreateVar(), SCIPdebugMsg, SCIPdebugPrintCons, SCIPinfinity(), SCIPlockVarCons(), SCIPreleaseCons(), SCIPsnprintf(), SCIPvarIsTransformed(), and TRUE.
Referenced by addExtendedFlowFormulation(), and SCIP_DECL_CONSPRESOL().
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creates LP row corresponding to xor constraint: x1 + ... + xn - 2q == rhs with internal integer variable q; in the special case of 3 variables and c = 0, the following linear system is created:
| scip | SCIP data structure |
| cons | constraint to check |
Definition at line 1592 of file cons_xor.c.
References addRelaxation(), lockRounding(), SCIP_CALL, SCIP_MAXSTRLEN, SCIP_OKAY, SCIP_Real, SCIP_VARTYPE_BINARY, SCIP_VARTYPE_INTEGER, SCIPaddVar(), SCIPaddVarsToRowSameCoef(), SCIPaddVarToRow(), SCIPconsGetData(), SCIPconsGetHdlr(), SCIPconsGetName(), SCIPconsIsInitial(), SCIPconsIsLocal(), SCIPconsIsModifiable(), SCIPconsIsRemovable(), SCIPcreateEmptyRowCons(), SCIPcreateVar(), SCIPdebugAddSolVal, SCIPdebugGetSolVal, SCIPinfinity(), and SCIPsnprintf().
Referenced by addExtendedAsymmetricFormulation(), addRelaxation(), and separateCons().
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adds linear relaxation of or constraint to the LP
| scip | SCIP data structure |
| cons | constraint to check |
| infeasible | pointer to store whether infeasibility was detected |
Definition at line 1725 of file cons_xor.c.
References allRowsInLP(), createRelaxation(), FALSE, NROWS, SCIP_Bool, SCIP_CALL, SCIP_OKAY, SCIPaddRow(), SCIPconsGetData(), and SCIProwIsInLP().
Referenced by createRelaxation(), and SCIP_DECL_CONSINITLP().
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returns whether all rows of the LP relaxation are in the current LP
| consdata | constraint data |
Definition at line 1757 of file cons_xor.c.
References checkCons(), FALSE, NROWS, SCIProwIsInLP(), and TRUE.
Referenced by addRelaxation(), and checkCons().
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checks xor constraint for feasibility of given solution: returns TRUE iff constraint is feasible
| scip | SCIP data structure |
| cons | constraint to check |
| sol | solution to check, NULL for current solution |
| checklprows | Do constraints represented by rows in the current LP have to be checked? |
| violated | pointer to store whether the constraint is violated |
Definition at line 1779 of file cons_xor.c.
References allRowsInLP(), FALSE, SCIP_Bool, SCIP_CALL, SCIP_OKAY, SCIP_Real, SCIPconsGetData(), SCIPgetSolVal(), SCIPincConsAge(), SCIPisFeasEQ(), SCIPisFeasIntegral(), SCIPresetConsAge(), SCIPupdateSolConsViolation(), separateCons(), and TRUE.
Referenced by allRowsInLP(), SCIP_DECL_CONSCHECK(), SCIP_DECL_CONSENFOLP(), SCIP_DECL_CONSENFOPS(), and SCIP_DECL_CONSENFORELAX().
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separates current LP solution
Consider a XOR-constraint
\[ x_1 \oplus x_2 \oplus \dots \oplus x_n = b \]
with \(b \in \{0,1\}\) and a solution \(x^*\) to be cut off. Small XOR constraints are handled by adding the inequalities of the convex hull.
The separation of larger XOR constraints has been described by
Xiaojie Zhang and Paul H. Siegel
"Adaptive Cut Generation Algorithm for Improved Linear Programming Decoding of Binary Linear Codes"
IEEE Transactions on Information Theory, vol. 58, no. 10, 2012
We separate the inequalities
\[ \sum_{j \in S} (1 - x_j) + \sum_{j \notin S} x_j \geq 1 \]
with \(|S| \equiv (b+1) \mbox{ mod } 2\) as follows. That these inequalities are valid can be seen as follows: Let \(x\) be a feasible solution and suppose that the inequality is violated for some \(S\). Then \(x_j = 1\) for all \(j \in S\) and \(x_j = 0\) for all \(j \notin S\). Thus we should have
\[ \oplus_{j \in S} x_j = |S| \mbox{ mod } 2 = b+1 \mbox{ mod } 2, \]
which is not equal to \(b\) as required by the XOR-constraint.
Let \(L= \{j \;:\; x^*_j > \frac{1}{2}\}\). Suppose that \(|L|\) has not the same parity as \(b\) rhs. Then
\[ \sum_{j \in L} (1 - x_j) + \sum_{j \notin L} x_j \geq 1 \]
is the only inequality that can be violated. We rewrite the inequality as
\[ \sum_{j \in L} x_j - \sum_{j \notin L} x_j \leq |L| - 1. \]
These inequalities are added.
Otherwise let \(k = \mbox{argmin}\{x^*_j \;:\; j \in L\}\) and check the inequality for \(L \setminus \{k\}\) and similarly for \(k = \mbox{argmax}\{x^*_j \;:\; j \in L\}\).
| scip | SCIP data structure |
| cons | constraint to check |
| sol | primal CIP solution, NULL for current LP solution |
| separateparity | should parity inequalities be separated? |
| separated | pointer to store whether a cut was found |
| cutoff | whether a cutoff has been detected |
Definition at line 1894 of file cons_xor.c.
References computeRowEcholonGF2(), createRelaxation(), FALSE, NROWS, SCIP_CALL, SCIP_MAXSTRLEN, SCIP_OKAY, SCIP_Real, SCIPaddRow(), SCIPaddVarToRow(), SCIPcacheRowExtensions(), SCIPconsGetData(), SCIPconsGetHdlr(), SCIPconsGetName(), SCIPcreateEmptyRowCons(), SCIPdebug, SCIPdebugMsg, SCIPflushRowExtensions(), SCIPgetRowLPActivity(), SCIPgetRowSolFeasibility(), SCIPgetSolVal(), SCIPinfinity(), SCIPisEfficacious(), SCIPisFeasGT(), SCIPisFeasNegative(), SCIPisGT(), SCIPprintRow(), SCIPreleaseRow(), SCIProwIsInLP(), SCIPsnprintf(), and TRUE.
Referenced by checkCons(), SCIP_DECL_CONSENFOLP(), SCIP_DECL_CONSENFORELAX(), SCIP_DECL_CONSSEPALP(), and SCIP_DECL_CONSSEPASOL().
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Transform linear system \(A x = b\) into row echolon form via the Gauss algorithm with row pivoting over GF2
A Here, \(A \in R^{m \times n},\; b \in R^m\). On exit, the vector p contains a permutation of the row indices used for pivoting and the function returns the rank r of A. For each row \(i = 1, \ldots, r\), the entry s[i] contains the column index of the first nonzero in row i.
| scip | SCIP data structure |
| m | number of rows |
| n | number of columns |
| p | row permutation |
| s | steps indicators of the row echolon form |
| A | matrix |
| b | rhs |
Definition at line 2107 of file cons_xor.c.
References SCIPisStopped(), and solveRowEcholonGF2().
Referenced by checkSystemGF2(), and separateCons().
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Construct solution from matrix in row echolon form over GF2
Compute solution of \(A x = b\), which is already in row echolon form (
| m | number of rows |
| n | number of columns |
| r | rank of matrix |
| p | row permutation |
| s | steps indicators of the row echolon form |
| A | matrix |
| b | rhs |
| x | solution vector on exit |
Definition at line 2216 of file cons_xor.c.
References checkSystemGF2().
Referenced by checkSystemGF2(), and computeRowEcholonGF2().
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solve equation system over GF 2 by Gauss algorithm and create solution out of it or return cutoff
Collect all information in xor constraints into a linear system over GF2. Then solve the system by computing a row echolon form. If the system is infeasible, the current node is infeasible. Otherwise, we can compute a solution for the xor constraints given. We check whether this gives a solution for the whole problem.
We sort the columns with respect to the product of the objective coefficients and 1 minus the current LP solution value. The idea is that columns that are likely to provide the steps in the row echolon form should appear towards the front of the matrix. The smaller the product, the more it makes sense to set the variable to 1 (because the solution value is already close to 1 and the objective function is small).
Note that this function is called from propagation where usually no solution is available. However, the solution is only used for sorting the columns. Thus, the procedure stays correct even with nonsense solutions.
| scip | SCIP data structure |
| conss | xor constraints |
| nconss | number of xor constraints |
| currentsol | current solution (maybe NULL) |
| result | result of propagation (possibly cutoff, no change if primal solution has been tried) |
Definition at line 2280 of file cons_xor.c.
References addConflictBounds(), BMSclearMemoryArray, computeRowEcholonGF2(), FALSE, MAXXORCONSSSYSTEM, MAXXORVARSSYSTEM, SCIP_Bool, SCIP_CALL, SCIP_CUTOFF, SCIP_OKAY, SCIP_Real, SCIP_VARSTATUS_AGGREGATED, SCIP_VARSTATUS_FIXED, SCIP_VARSTATUS_MULTAGGR, SCIP_VARTYPE_BINARY, SCIPallocBufferArray, SCIPblkmem(), SCIPcheckSol(), SCIPcomputeVarLbLocal(), SCIPcomputeVarUbLocal(), SCIPconsGetData(), SCIPconsGetName(), SCIPcreateSol(), SCIPdebug, SCIPdebugMsg, SCIPfindHeur(), SCIPfreeBufferArray, SCIPfreeSol(), SCIPgetNVars(), SCIPgetSolVal(), SCIPgetVars(), SCIPhashmapCreate(), SCIPhashmapExists(), SCIPhashmapFree(), SCIPhashmapGetImage(), SCIPhashmapInsert(), SCIPheurPassSolAddSol(), SCIPinfoMessage(), SCIPisEQ(), SCIPisGE(), SCIPisLE(), SCIPisStopped(), SCIPprintSol(), SCIPsetSolVal(), SCIPsortRealIntPtr(), SCIPtightenVarLb(), SCIPtightenVarUb(), SCIPvarGetAggrConstant(), SCIPvarGetAggrScalar(), SCIPvarGetAggrVar(), SCIPvarGetLbGlobal(), SCIPvarGetName(), SCIPvarGetNegatedVar(), SCIPvarGetObj(), SCIPvarGetStatus(), SCIPvarGetType(), SCIPvarGetUbGlobal(), SCIPvarIsActive(), SCIPvarIsNegated(), solveRowEcholonGF2(), and TRUE.
Referenced by SCIP_DECL_CONSPROP(), and solveRowEcholonGF2().
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for each variable in the xor constraint, add it to conflict set; for integral variable add corresponding bound
| scip | SCIP data structure |
| cons | constraint that inferred the bound change |
| infervar | variable that was deduced, or NULL (not equal to integral variable) |
| bdchgidx | bound change index (time stamp of bound change), or NULL for current time |
| proprule | propagation rule |
Definition at line 2760 of file cons_xor.c.
References analyzeConflict(), FALSE, PROPRULE_0, PROPRULE_1, PROPRULE_INTLB, PROPRULE_INTUB, PROPRULE_INVALID, SCIP_CALL, SCIP_INVALIDDATA, SCIP_OKAY, SCIPABORT, SCIPaddConflictBinvar(), SCIPaddConflictLb(), SCIPaddConflictUb(), SCIPconsGetData(), SCIPconsGetName(), SCIPerrorMessage, SCIPgetVarLbAtIndex(), SCIPgetVarUbAtIndex(), SCIPisEQ(), and TRUE.
Referenced by analyzeConflict(), checkSystemGF2(), and resolvePropagation().
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analyzes conflicting assignment on given constraint, and adds conflict constraint to problem
| scip | SCIP data structure |
| cons | xor constraint that detected the conflict |
| infervar | variable that was deduced, or NULL (not equal to integral variable) |
| proprule | propagation rule |
Definition at line 2868 of file cons_xor.c.
References addConflictBounds(), FALSE, propagateCons(), SCIP_CALL, SCIP_CONFTYPE_PROPAGATION, SCIP_OKAY, SCIP_STAGE_SOLVING, SCIPanalyzeConflictCons(), SCIPgetStage(), SCIPinitConflictAnalysis(), SCIPinProbing(), and SCIPisConflictAnalysisApplicable().
Referenced by addConflictBounds(), and propagateCons().
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propagates constraint with the following rules: (0) all variables are fixed => can fix integral variable (1) all except one variable fixed => fix remaining variable and integral variable (2) depending on the amount of fixed binary variables we can tighten the integral variable (3) depending on the lower bound of the integral variable one can fix variables to 1 (4) depending on the upper bound of the integral variable one can fix variables to 0
| scip | SCIP data structure |
| cons | xor constraint to be processed |
| eventhdlr | event handler to call for the event processing |
| cutoff | pointer to store TRUE, if the node can be cut off |
| nfixedvars | pointer to add up the number of fixed variables |
| nchgbds | pointer to add up the number of found domain reductions |
Definition at line 2899 of file cons_xor.c.
References analyzeConflict(), consdataSwitchWatchedvars(), FALSE, PROPRULE_0, PROPRULE_1, PROPRULE_INTLB, PROPRULE_INTUB, resolvePropagation(), SCIP_Bool, SCIP_CALL, SCIP_OKAY, SCIP_Real, SCIPconsGetData(), SCIPconsGetName(), SCIPconsIsModifiable(), SCIPdebugMsg, SCIPdelConsLocal(), SCIPincConsAge(), SCIPinferBinvarCons(), SCIPinferVarLbCons(), SCIPinferVarUbCons(), SCIPinRepropagation(), SCIPisEQ(), SCIPisFeasEQ(), SCIPisFeasIntegral(), SCIPresetConsAge(), SCIPvarGetLbLocal(), SCIPvarGetName(), SCIPvarGetUbLocal(), and TRUE.
Referenced by analyzeConflict(), SCIP_DECL_CONSPRESOL(), and SCIP_DECL_CONSPROP().
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resolves a conflict on the given variable by supplying the variables needed for applying the corresponding propagation rules (see propagateCons())
| scip | SCIP data structure |
| cons | constraint that inferred the bound change |
| infervar | variable that was deduced |
| proprule | propagation rule that deduced the value |
| bdchgidx | bound change index (time stamp of bound change), or NULL for current time |
| result | pointer to store the result of the propagation conflict resolving call |
Definition at line 3297 of file cons_xor.c.
References addConflictBounds(), cliquePresolve(), SCIP_CALL, SCIP_OKAY, SCIP_SUCCESS, and SCIPdebugMsg.
Referenced by propagateCons(), and SCIP_DECL_CONSRESPROP().
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try to use clique information to delete a part of the xor constraint or even fix variables
| scip | SCIP data structure |
| cons | constraint that inferred the bound change |
| nfixedvars | pointer to add up the number of found domain reductions |
| nchgcoefs | pointer to add up the number of deleted entries |
| ndelconss | pointer to add up the number of deleted constraints |
| naddconss | pointer to add up the number of added constraints |
| cutoff | pointer to store TRUE, if the node can be cut off |
Definition at line 3318 of file cons_xor.c.
References detectRedundantConstraints(), FALSE, SCIP_Bool, SCIP_CALL, SCIP_MAXSTRLEN, SCIP_OKAY, SCIP_VARSTATUS_FIXED, SCIP_VARSTATUS_NEGATED, SCIPaddCoefSetppc(), SCIPaddCons(), SCIPconsGetData(), SCIPconsGetName(), SCIPconsIsChecked(), SCIPconsIsDynamic(), SCIPconsIsEnforced(), SCIPconsIsInitial(), SCIPconsIsLocal(), SCIPconsIsModifiable(), SCIPconsIsPropagated(), SCIPconsIsRemovable(), SCIPconsIsSeparated(), SCIPconsIsStickingAtNode(), SCIPcreateConsSetpart(), SCIPdebug, SCIPdebugMsg, SCIPdelCons(), SCIPfixVar(), SCIPgetNegatedVar(), SCIPprintCons(), SCIPreleaseCons(), SCIPsnprintf(), SCIPvarGetName(), SCIPvarGetNegationVar(), SCIPvarGetStatus(), SCIPvarIsActive(), SCIPvarsHaveCommonClique(), and TRUE.
Referenced by resolvePropagation(), and SCIP_DECL_CONSPRESOL().
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compares each constraint with all other constraints for possible redundancy and removes or changes constraint accordingly; in contrast to preprocessConstraintPairs(), it uses a hash table
| scip | SCIP data structure |
| blkmem | block memory |
| conss | constraint set |
| nconss | number of constraints in constraint set |
| firstchange | pointer to store first changed constraint |
| nchgcoefs | pointer to add up the number of changed coefficients |
| naggrvars | pointer to add up the number of aggregated variables |
| ndelconss | pointer to count number of deleted constraints |
| naddconss | pointer to count number of added constraints |
| cutoff | pointer to store TRUE, if a cutoff was found |
Definition at line 3611 of file cons_xor.c.
References applyFixings(), consdataSort(), HASHSIZE_XORCONS, MAX, preprocessConstraintPairs(), SCIP_CALL, SCIP_OKAY, SCIPconsGetData(), SCIPconsGetHdlr(), SCIPconsGetPos(), SCIPconshdlrGetData(), SCIPconsIsActive(), SCIPconsIsModifiable(), SCIPdelCons(), SCIPhashtableCreate(), SCIPhashtableFree(), SCIPhashtableInsert(), SCIPhashtableRetrieve(), SCIPupdateConsFlags(), and TRUE.
Referenced by cliquePresolve(), and SCIP_DECL_CONSPRESOL().
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compares constraint with all prior constraints for possible redundancy or aggregation, and removes or changes constraint accordingly
| scip | SCIP data structure |
| conss | constraint set |
| firstchange | first constraint that changed since last pair preprocessing round |
| chkind | index of constraint to check against all prior indices upto startind |
| cutoff | pointer to store TRUE, if a cutoff was found |
| nfixedvars | pointer to add up the number of found domain reductions |
| naggrvars | pointer to count number of aggregated variables |
| ndelconss | pointer to count number of deleted constraints |
| naddconss | pointer to count number of added constraints |
| nchgcoefs | pointer to add up the number of changed coefficients |
Definition at line 3728 of file cons_xor.c.
References addCoef(), applyFixings(), consdataSort(), createConsXorIntvar(), FALSE, SCIP_Bool, SCIP_CALL, SCIP_INVALIDDATA, SCIP_MAXSTRLEN, SCIP_OKAY, SCIP_Real, SCIPABORT, SCIPaddCons(), SCIPaggregateVars(), SCIPconsGetData(), SCIPconsGetHdlr(), SCIPconsGetName(), SCIPconshdlrGetData(), SCIPconsIsActive(), SCIPconsIsDynamic(), SCIPconsIsInitial(), SCIPconsIsLocal(), SCIPconsIsModifiable(), SCIPconsIsRemovable(), SCIPconsIsSeparated(), SCIPconsIsStickingAtNode(), SCIPcreateConsLinear(), SCIPdebugMsg, SCIPdebugPrintCons, SCIPdelCons(), SCIPdoNotAggr(), SCIPerrorMessage, SCIPfixVar(), SCIPisStopped(), SCIPreleaseCons(), SCIPsnprintf(), SCIPupdateConsFlags(), SCIPvarCompareActiveAndNegated(), SCIPvarGetName(), SCIPvarGetNegatedVar(), SCIPvarGetProbvar(), SCIPvarIsActive(), setIntvar(), and TRUE.
Referenced by detectRedundantConstraints(), and SCIP_DECL_CONSPRESOL().
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creates and captures a xor constraint x_0 xor ... xor x_{k-1} = rhs with a given artificial integer variable for the linear relaxation
| scip | SCIP data structure |
| cons | pointer to hold the created constraint |
| name | name of constraint |
| rhs | right hand side of the constraint |
| nvars | number of operator variables in the constraint |
| vars | array with operator variables of constraint |
| intvar | artificial integer variable for linear relaxation |
| initial | should the LP relaxation of constraint be in the initial LP? Usually set to TRUE. Set to FALSE for 'lazy constraints'. |
| separate | should the constraint be separated during LP processing? Usually set to TRUE. |
| enforce | should the constraint be enforced during node processing? TRUE for model constraints, FALSE for additional, redundant constraints. |
| check | should the constraint be checked for feasibility? TRUE for model constraints, FALSE for additional, redundant constraints. |
| propagate | should the constraint be propagated during node processing? Usually set to TRUE. |
| local | is constraint only valid locally? Usually set to FALSE. Has to be set to TRUE, e.g., for branching constraints. |
| modifiable | is constraint modifiable (subject to column generation)? Usually set to FALSE. In column generation applications, set to TRUE if pricing adds coefficients to this constraint. |
| dynamic | is constraint subject to aging? Usually set to FALSE. Set to TRUE for own cuts which are separated as constraints. |
| removable | should the relaxation be removed from the LP due to aging or cleanup? Usually set to FALSE. Set to TRUE for 'lazy constraints' and 'user cuts'. |
| stickingatnode | should the constraint always be kept at the node where it was added, even if it may be moved to a more global node? Usually set to FALSE. Set to TRUE to for constraints that represent node data. |
Definition at line 4260 of file cons_xor.c.
References consdataCreate(), CONSHDLR_NAME, SCIP_CALL, SCIP_DECL_LINCONSUPGD(), SCIP_OKAY, SCIP_PLUGINNOTFOUND, SCIPcreateCons(), SCIPerrorMessage, and SCIPfindConshdlr().
Referenced by preprocessConstraintPairs(), SCIP_DECL_CONSCOPY(), SCIP_DECL_CONSPARSE(), and SCIP_DECL_LINCONSUPGD().
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tries to upgrade a linear constraint into an xor constraint
Assuming the only coefficients with an absolute value unequal to one is two in absolute value we can transform:
\[ \begin{array}{ll} & -\sum_{i \in I} x_i + \sum_{j \in J} x_j + a \cdot z = rhs \\ \Leftrightarrow & \sum_{i \in I} ~x_i + \sum_j x_{j \in J} + a \cdot z = rhs + |I| \\ \Leftrightarrow & \sum_{i \in I} ~x_i + \sum_j x_{j \in J} - 2 \cdot y = (rhs + |I|) mod 2 \\ & z \in [lb_z,ub_z] \Rightarrow y \in (\left\lfloor \frac{rhs + |I|}{2} \right\rfloor + (a = -2\; ?\; lb_z : -ub_z), \left\lfloor \frac{rhs + |I|}{2} \right\rfloor + (a = -2\; ?\; ub_z : -lb_z) ) \\ & z = (a = -2\; ?\; y - \left\lfloor \frac{rhs + |I|}{2} \right\rfloor\; :\; -y + \left\lfloor \frac{rhs + |I|}{2} \right\rfloor) \end{array} \]
Definition at line 4334 of file cons_xor.c.
References createConsXorIntvar(), FALSE, REALABS, SCIP_Bool, SCIP_CALL, SCIP_DECL_CONSHDLRCOPY(), SCIP_MAXSTRLEN, SCIP_OKAY, SCIP_Real, SCIP_VARTYPE_BINARY, SCIP_VARTYPE_INTEGER, SCIPaddVar(), SCIPaggregateVars(), SCIPallocBufferArray, SCIPconsGetHdlr(), SCIPconsGetName(), SCIPconshdlrGetName(), SCIPconsIsChecked(), SCIPconsIsDynamic(), SCIPconsIsEnforced(), SCIPconsIsInitial(), SCIPconsIsLocal(), SCIPconsIsModifiable(), SCIPconsIsPropagated(), SCIPconsIsRemovable(), SCIPconsIsSeparated(), SCIPconsIsStickingAtNode(), SCIPcreateVar(), SCIPdebug, SCIPdebugMsg, SCIPdebugPrintCons, SCIPfeasFloor(), SCIPfloor(), SCIPfreeBufferArray, SCIPgetNegatedVar(), SCIPisEQ(), SCIPisFeasIntegral(), SCIPisFeasLE(), SCIPisIntegral(), SCIPisZero(), SCIPprintVar(), SCIPreleaseVar(), SCIPsnprintf(), SCIPvarGetAggrConstant(), SCIPvarGetAggrScalar(), SCIPvarGetAggrVar(), SCIPvarGetLbGlobal(), SCIPvarGetName(), SCIPvarGetNLocksDown(), SCIPvarGetNLocksUp(), SCIPvarGetUbGlobal(), SCIPvarIsActive(), SCIPvarIsBinary(), SCIPvarIsInitial(), and SCIPvarIsRemovable().
Referenced by createConsXorIntvar().
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copy method for constraint handler plugins (called when SCIP copies plugins)
Definition at line 4518 of file cons_xor.c.
References CONSHDLR_NAME, SCIP_CALL, SCIP_DECL_CONSFREE(), SCIP_OKAY, SCIPconshdlrGetName(), SCIPincludeConshdlrXor(), and TRUE.
Referenced by SCIP_DECL_LINCONSUPGD().
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destructor of constraint handler to free constraint handler data (called when SCIP is exiting)
Definition at line 4534 of file cons_xor.c.
References conshdlrdataFree(), SCIP_CALL, SCIP_DECL_CONSEXITSOL(), SCIP_OKAY, SCIPconshdlrGetData(), and SCIPconshdlrSetData().
Referenced by SCIP_DECL_CONSHDLRCOPY().
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solving process deinitialization method of constraint handler (called before branch and bound process data is freed)
Definition at line 4551 of file cons_xor.c.
References consdataFreeRows(), SCIP_CALL, SCIP_DECL_CONSDELETE(), SCIP_OKAY, and SCIPconsGetData().
Referenced by SCIP_DECL_CONSFREE().
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frees specific constraint data
Definition at line 4569 of file cons_xor.c.
References consdataFree(), SCIP_CALL, SCIP_DECL_CONSTRANS(), SCIP_EVENTTYPE_VARFIXED, SCIP_OKAY, SCIP_STAGE_INITPRESOLVE, SCIP_STAGE_PRESOLVING, SCIPconshdlrGetData(), SCIPdropVarEvent(), and SCIPgetStage().
Referenced by SCIP_DECL_CONSEXITSOL().
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transforms constraint data into data belonging to the transformed problem
Definition at line 4595 of file cons_xor.c.
References consdataCreate(), SCIP_CALL, SCIP_DECL_CONSINITLP(), SCIP_OKAY, SCIPconsGetData(), SCIPconsGetName(), SCIPconsIsChecked(), SCIPconsIsDynamic(), SCIPconsIsEnforced(), SCIPconsIsInitial(), SCIPconsIsLocal(), SCIPconsIsModifiable(), SCIPconsIsPropagated(), SCIPconsIsRemovable(), SCIPconsIsSeparated(), SCIPconsIsStickingAtNode(), and SCIPcreateCons().
Referenced by SCIP_DECL_CONSDELETE().
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LP initialization method of constraint handler (called before the initial LP relaxation at a node is solved)
Definition at line 4621 of file cons_xor.c.
References addRelaxation(), FALSE, SCIP_CALL, SCIP_DECL_CONSSEPALP(), SCIP_OKAY, and SCIPconsIsInitial().
Referenced by SCIP_DECL_CONSTRANS().
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separation method of constraint handler for LP solutions
Definition at line 4641 of file cons_xor.c.
References SCIP_Bool, SCIP_CALL, SCIP_CUTOFF, SCIP_DECL_CONSSEPASOL(), SCIP_DIDNOTFIND, SCIP_OKAY, SCIP_SEPARATED, SCIPconshdlrGetData(), and separateCons().
Referenced by SCIP_DECL_CONSINITLP().
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separation method of constraint handler for arbitrary primal solutions
Definition at line 4672 of file cons_xor.c.
References SCIP_Bool, SCIP_CALL, SCIP_CUTOFF, SCIP_DECL_CONSENFOLP(), SCIP_DIDNOTFIND, SCIP_OKAY, SCIP_SEPARATED, SCIPconshdlrGetData(), and separateCons().
Referenced by SCIP_DECL_CONSSEPALP().
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constraint enforcing method of constraint handler for LP solutions
Definition at line 4703 of file cons_xor.c.
References checkCons(), FALSE, SCIP_Bool, SCIP_CALL, SCIP_CUTOFF, SCIP_DECL_CONSENFORELAX(), SCIP_FEASIBLE, SCIP_OKAY, SCIP_SEPARATED, SCIPconshdlrGetData(), and separateCons().
Referenced by SCIP_DECL_CONSSEPASOL().
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constraint enforcing method of constraint handler for relaxation solutions
Definition at line 4740 of file cons_xor.c.
References checkCons(), FALSE, SCIP_Bool, SCIP_CALL, SCIP_CUTOFF, SCIP_DECL_CONSENFOPS(), SCIP_FEASIBLE, SCIP_OKAY, SCIP_SEPARATED, SCIPconshdlrGetData(), and separateCons().
Referenced by SCIP_DECL_CONSENFOLP().
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constraint enforcing method of constraint handler for pseudo solutions
Definition at line 4777 of file cons_xor.c.
References checkCons(), SCIP_Bool, SCIP_CALL, SCIP_DECL_CONSCHECK(), SCIP_FEASIBLE, SCIP_INFEASIBLE, SCIP_OKAY, and TRUE.
Referenced by SCIP_DECL_CONSENFORELAX().
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feasibility check method of constraint handler for integral solutions
Definition at line 4800 of file cons_xor.c.
References checkCons(), SCIP_Bool, SCIP_CALL, SCIP_DECL_CONSPROP(), SCIP_FEASIBLE, SCIP_INFEASIBLE, SCIP_OKAY, SCIPconsGetData(), SCIPgetSolVal(), SCIPinfoMessage(), and SCIPprintCons().
Referenced by SCIP_DECL_CONSENFOPS().
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domain propagation method of constraint handler
Definition at line 4850 of file cons_xor.c.
References checkSystemGF2(), FALSE, propagateCons(), SCIP_Bool, SCIP_CALL, SCIP_CUTOFF, SCIP_DECL_CONSINITPRE(), SCIP_DIDNOTFIND, SCIP_OKAY, SCIP_REDUCEDDOM, SCIPconshdlrGetData(), SCIPgetDepth(), and SCIPinProbing().
Referenced by SCIP_DECL_CONSCHECK().
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presolving initialization method of constraint handler (called when presolving is about to begin)
Definition at line 4899 of file cons_xor.c.
References SCIP_CALL, SCIP_DECL_CONSEXITPRE(), SCIP_EVENTTYPE_VARFIXED, SCIP_OKAY, SCIPcatchVarEvent(), SCIPconsGetData(), and SCIPconshdlrGetData().
Referenced by SCIP_DECL_CONSPROP().
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presolving deinitialization method of constraint handler (called after presolving has been finished)
Definition at line 4928 of file cons_xor.c.
References SCIP_CALL, SCIP_DECL_CONSPRESOL(), SCIP_EVENTTYPE_VARFIXED, SCIP_OKAY, SCIPconsGetData(), SCIPconshdlrGetData(), SCIPconsIsDeleted(), and SCIPdropVarEvent().
Referenced by SCIP_DECL_CONSINITPRE().
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presolving method of constraint handler
Definition at line 4960 of file cons_xor.c.
References addExtendedAsymmetricFormulation(), addExtendedFlowFormulation(), applyFixings(), cliquePresolve(), detectRedundantConstraints(), FALSE, MINGAINPERNMINCOMPARISONS, NMINCOMPARISONS, preprocessConstraintPairs(), propagateCons(), SCIP_Bool, SCIP_CALL, SCIP_CUTOFF, SCIP_DECL_CONSRESPROP(), SCIP_DIDNOTFIND, SCIP_Longint, SCIP_OKAY, SCIP_PRESOLTIMING_EXHAUSTIVE, SCIP_PRESOLTIMING_MEDIUM, SCIP_Real, SCIP_SUCCESS, SCIPaggregateVars(), SCIPblkmem(), SCIPconsGetData(), SCIPconsGetName(), SCIPconshdlrGetData(), SCIPconsIsActive(), SCIPconsIsDeleted(), SCIPconsIsModifiable(), SCIPdebugMsg, SCIPdelCons(), SCIPdoNotAggr(), SCIPisEQ(), SCIPisPresolveFinished(), SCIPisStopped(), SCIPvarGetLbGlobal(), SCIPvarGetName(), SCIPvarGetUbGlobal(), and TRUE.
Referenced by SCIP_DECL_CONSEXITPRE().
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propagation conflict resolving method of constraint handler
Definition at line 5174 of file cons_xor.c.
References resolvePropagation(), SCIP_CALL, SCIP_DECL_CONSLOCK(), and SCIP_OKAY.
Referenced by SCIP_DECL_CONSPRESOL().
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variable rounding lock method of constraint handler
Definition at line 5184 of file cons_xor.c.
References SCIP_CALL, SCIP_DECL_CONSPRINT(), SCIP_OKAY, SCIPaddVarLocks(), and SCIPconsGetData().
Referenced by SCIP_DECL_CONSRESPROP().
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constraint display method of constraint handler
Definition at line 5210 of file cons_xor.c.
References consdataPrint(), FALSE, SCIP_CALL, SCIP_DECL_CONSCOPY(), SCIP_OKAY, and SCIPconsGetData().
Referenced by SCIP_DECL_CONSLOCK().
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constraint copying method of constraint handler
Definition at line 5223 of file cons_xor.c.
References createConsXorIntvar(), SCIP_CALL, SCIP_DECL_CONSPARSE(), SCIP_OKAY, SCIPallocBufferArray, SCIPconsGetData(), SCIPconsGetName(), SCIPdebugMsg, SCIPfreeBufferArray, SCIPgetRhsXor(), SCIPgetVarCopy(), SCIPvarGetLbGlobal(), SCIPvarGetLbLocal(), SCIPvarGetName(), SCIPvarGetUbGlobal(), SCIPvarGetUbLocal(), and TRUE.
Referenced by SCIP_DECL_CONSPRINT().
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constraint parsing method of constraint handler
Definition at line 5314 of file cons_xor.c.
References createConsXorIntvar(), FALSE, SCIP_CALL, SCIP_DECL_CONSGETVARS(), SCIP_OKAY, SCIP_Real, SCIPallocBufferArray, SCIPcreateConsXor(), SCIPdebugMsg, SCIPdebugPrintCons, SCIPerrorMessage, SCIPfreeBufferArray, SCIPisEQ(), SCIPisZero(), SCIPparseVarName(), SCIPparseVarsList(), SCIPreallocBufferArray, SCIPstrToRealValue(), SCIPvarGetName(), and TRUE.
Referenced by SCIP_DECL_CONSCOPY().
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constraint method of constraint handler which returns the variables (if possible)
Definition at line 5446 of file cons_xor.c.
References BMScopyMemoryArray, FALSE, SCIP_DECL_CONSGETNVARS(), SCIP_OKAY, SCIPconsGetData(), and TRUE.
Referenced by SCIP_DECL_CONSPARSE().
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constraint method of constraint handler which returns the number of variable (if possible)
Definition at line 5488 of file cons_xor.c.
References SCIP_DECL_EVENTEXEC(), SCIP_OKAY, SCIPconsGetData(), and TRUE.
Referenced by SCIP_DECL_CONSGETVARS().
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Definition at line 5512 of file cons_xor.c.
References FALSE, SCIP_EVENTTYPE_VARFIXED, SCIP_OKAY, SCIP_STAGE_PRESOLVING, SCIPeventGetType(), SCIPeventGetVar(), SCIPgetStage(), and SCIPincludeConshdlrXor().
Referenced by SCIP_DECL_CONSGETNVARS().