Scippy

SCIP

Solving Constraint Integer Programs

cons_sos2.h File Reference

Detailed Description

constraint handler for SOS type 2 constraints

Author
Marc Pfetsch

A specially ordered set of type 2 (SOS2) is a sequence of variables such that at most two variables are nonzero and if two variables are nonzero they must be adjacent in the specified sequence. Note that it is in principle allowed that a variable appears twice, but it then can be fixed to 0 if it is at least two apart in the sequence.

Definition in file cons_sos2.h.

#include "scip/scip.h"

Go to the source code of this file.

Functions

SCIP_RETCODE SCIPincludeConshdlrSOS2 (SCIP *scip)
 
SCIP_RETCODE SCIPcreateConsSOS2 (SCIP *scip, SCIP_CONS **cons, const char *name, int nvars, SCIP_VAR **vars, SCIP_Real *weights, 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 SCIPcreateConsBasicSOS2 (SCIP *scip, SCIP_CONS **cons, const char *name, int nvars, SCIP_VAR **vars, SCIP_Real *weights)
 
SCIP_RETCODE SCIPaddVarSOS2 (SCIP *scip, SCIP_CONS *cons, SCIP_VAR *var, SCIP_Real weight)
 
SCIP_RETCODE SCIPappendVarSOS2 (SCIP *scip, SCIP_CONS *cons, SCIP_VAR *var)
 
int SCIPgetNVarsSOS2 (SCIP *scip, SCIP_CONS *cons)
 
SCIP_VAR ** SCIPgetVarsSOS2 (SCIP *scip, SCIP_CONS *cons)
 
SCIP_RealSCIPgetWeightsSOS2 (SCIP *scip, SCIP_CONS *cons)
 

Function Documentation

SCIP_RETCODE SCIPincludeConshdlrSOS2 ( SCIP scip)

creates the handler for SOS2 constraints and includes it in SCIP

Parameters
scipSCIP data structure
SCIP_RETCODE SCIPcreateConsSOS2 ( SCIP scip,
SCIP_CONS **  cons,
const char *  name,
int  nvars,
SCIP_VAR **  vars,
SCIP_Real weights,
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 
)

creates and captures an SOS2 constraint

We set the constraint to not be modifable. If the weights are non NULL, the variables are ordered according to these weights (in ascending order).

Note
the constraint gets captured, hence at one point you have to release it using the method SCIPreleaseCons()
Parameters
scipSCIP data structure
conspointer to hold the created constraint
namename of constraint
nvarsnumber of variables in the constraint
varsarray with variables of constraint entries
weightsweights determining the variable order, or NULL if natural order should be used
initialshould the LP relaxation of constraint be in the initial LP? Usually set to TRUE. Set to FALSE for 'lazy constraints'.
separateshould the constraint be separated during LP processing? Usually set to TRUE.
enforceshould the constraint be enforced during node processing? TRUE for model constraints, FALSE for additional, redundant constraints.
checkshould the constraint be checked for feasibility? TRUE for model constraints, FALSE for additional, redundant constraints.
propagateshould the constraint be propagated during node processing? Usually set to TRUE.
localis constraint only valid locally? Usually set to FALSE. Has to be set to TRUE, e.g., for branching constraints.
dynamicis constraint subject to aging? Usually set to FALSE. Set to TRUE for own cuts which are separated as constraints.
removableshould 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'.
stickingatnodeshould 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.
SCIP_RETCODE SCIPcreateConsBasicSOS2 ( SCIP scip,
SCIP_CONS **  cons,
const char *  name,
int  nvars,
SCIP_VAR **  vars,
SCIP_Real weights 
)

creates and captures a SOS2 constraint with all constraint flags set to their default values.

Warning
Do NOT set the constraint to be modifiable manually, because this might lead to wrong results as the variable array will not be resorted
Note
the constraint gets captured, hence at one point you have to release it using the method SCIPreleaseCons()
Parameters
scipSCIP data structure
conspointer to hold the created constraint
namename of constraint
nvarsnumber of variables in the constraint
varsarray with variables of constraint entries
weightsweights determining the variable order, or NULL if natural order should be used
SCIP_RETCODE SCIPaddVarSOS2 ( SCIP scip,
SCIP_CONS cons,
SCIP_VAR var,
SCIP_Real  weight 
)

adds variable to SOS2 constraint, the position is determined by the given weight

Parameters
scipSCIP data structure
consconstraint
varvariable to add to the constraint
weightweight determining position of variable
SCIP_RETCODE SCIPappendVarSOS2 ( SCIP scip,
SCIP_CONS cons,
SCIP_VAR var 
)

appends variable to SOS2 constraint

Parameters
scipSCIP data structure
consconstraint
varvariable to add to the constraint
int SCIPgetNVarsSOS2 ( SCIP scip,
SCIP_CONS cons 
)

gets number of variables in SOS2 constraint

Parameters
scipSCIP data structure
consconstraint
SCIP_VAR** SCIPgetVarsSOS2 ( SCIP scip,
SCIP_CONS cons 
)

gets array of variables in SOS2 constraint

Parameters
scipSCIP data structure
consconstraint data
SCIP_Real* SCIPgetWeightsSOS2 ( SCIP scip,
SCIP_CONS cons 
)

gets array of weights in SOS2 constraint (or NULL if not existent)

Parameters
scipSCIP data structure
consconstraint data