Scippy

SCIP

Solving Constraint Integer Programs

Functions
cons_indicator.h File Reference
Public API of SCIP » Plugin API of SCIP » Constraint Handler

Detailed Description

constraint handler for indicator constraints

Author
Marc Pfetsch

Definition in file cons_indicator.h.

#include "scip/def.h"
#include "scip/type_cons.h"
#include "scip/type_lp.h"
#include "scip/type_retcode.h"
#include "scip/type_scip.h"
#include "scip/type_sol.h"
#include "scip/type_var.h"

Go to the source code of this file.

Functions

SCIP_RETCODE SCIPincludeConshdlrIndicator (SCIP *scip)
 
Indicator Constraints

An indicator constraint is given by a binary variable \(z\) and an inequality \(ax \leq b\). It states that if \(z = 1\) then \(ax \leq b\) holds.

This constraint is handled by adding a slack variable \(s:\; ax - s \leq b\) with \(s \geq 0\). The constraint is enforced by fixing \(s\) to 0 if \(z = 1\).

Note
The constraint only implements an implication not an equivalence, i.e., it does not ensure that \(z = 1\) if \(ax \leq b\) or equivalently if \(s = 0\) holds.

This constraint is equivalent to a linear constraint \(ax - s \leq b\) and an SOS1 constraint on \(z\) and \(s\) (at most one should be nonzero). In the indicator context we can, however, separate more inequalities.

SCIP_RETCODE SCIPcreateConsIndicator (SCIP *scip, SCIP_CONS **cons, const char *name, SCIP_VAR *binvar, int nvars, SCIP_VAR **vars, SCIP_Real *vals, SCIP_Real rhs, SCIP_Bool initial, SCIP_Bool separate, SCIP_Bool enforce, SCIP_Bool check, SCIP_Bool propagate, SCIP_Bool local, SCIP_Bool dynamic, SCIP_Bool removable, SCIP_Bool stickingatnode)
 
SCIP_RETCODE SCIPcreateConsBasicIndicator (SCIP *scip, SCIP_CONS **cons, const char *name, SCIP_VAR *binvar, int nvars, SCIP_VAR **vars, SCIP_Real *vals, SCIP_Real rhs)
 
SCIP_RETCODE SCIPcreateConsIndicatorLinCons (SCIP *scip, SCIP_CONS **cons, const char *name, SCIP_VAR *binvar, SCIP_CONS *lincons, SCIP_VAR *slackvar, SCIP_Bool initial, SCIP_Bool separate, SCIP_Bool enforce, SCIP_Bool check, SCIP_Bool propagate, SCIP_Bool local, SCIP_Bool dynamic, SCIP_Bool removable, SCIP_Bool stickingatnode)
 
SCIP_RETCODE SCIPcreateConsBasicIndicatorLinCons (SCIP *scip, SCIP_CONS **cons, const char *name, SCIP_VAR *binvar, SCIP_CONS *lincons, SCIP_VAR *slackvar)
 
SCIP_RETCODE SCIPaddVarIndicator (SCIP *scip, SCIP_CONS *cons, SCIP_VAR *var, SCIP_Real val)
 
SCIP_CONS * SCIPgetLinearConsIndicator (SCIP_CONS *cons)
 
SCIP_RETCODE SCIPsetLinearConsIndicator (SCIP *scip, SCIP_CONS *cons, SCIP_CONS *lincons)
 
SCIP_RETCODE SCIPsetBinaryVarIndicator (SCIP *scip, SCIP_CONS *cons, SCIP_VAR *binvar)
 
SCIP_VAR * SCIPgetBinaryVarIndicator (SCIP_CONS *cons)
 
SCIP_VAR * SCIPgetSlackVarIndicator (SCIP_CONS *cons)
 
SCIP_RETCODE SCIPsetSlackVarUb (SCIP *scip, SCIP_CONS *cons, SCIP_Real ub)
 
SCIP_Bool SCIPisViolatedIndicator (SCIP *scip, SCIP_CONS *cons, SCIP_SOL *sol)
 
SCIP_RETCODE SCIPmakeIndicatorFeasible (SCIP *scip, SCIP_CONS *cons, SCIP_SOL *sol, SCIP_Bool *changed)
 
SCIP_RETCODE SCIPmakeIndicatorsFeasible (SCIP *scip, SCIP_CONSHDLR *conshdlr, SCIP_SOL *sol, SCIP_Bool *changed)
 
SCIP_RETCODE SCIPaddLinearConsIndicator (SCIP *scip, SCIP_CONSHDLR *conshdlr, SCIP_CONS *lincons)
 
SCIP_RETCODE SCIPaddRowIndicator (SCIP *scip, SCIP_CONSHDLR *conshdlr, SCIP_ROW *row)