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_Real *	SCIPgetWeightsSOS2 (SCIP scip, SCIP_CONS cons)

Function Documentation

SCIP_RETCODE SCIPincludeConshdlrSOS2 ( SCIP * scip )

creates the handler for SOS2 constraints and includes it in SCIP

Parameters

scip	SCIP 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

scip	SCIP data structure
cons	pointer to hold the created constraint
name	name of constraint
nvars	number of variables in the constraint
vars	array with variables of constraint entries
weights	weights determining the variable order, or NULL if natural order should be used
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.
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.

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

scip	SCIP data structure
cons	pointer to hold the created constraint
name	name of constraint
nvars	number of variables in the constraint
vars	array with variables of constraint entries
weights	weights 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

scip	SCIP data structure
cons	constraint
var	variable to add to the constraint
weight	weight determining position of variable

SCIP_RETCODE SCIPappendVarSOS2	(	SCIP *	scip,
		SCIP_CONS *	cons,
		SCIP_VAR *	var
	)

appends variable to SOS2 constraint

Parameters

scip	SCIP data structure
cons	constraint
var	variable to add to the constraint

int SCIPgetNVarsSOS2	(	SCIP *	scip,
		SCIP_CONS *	cons
	)

gets number of variables in SOS2 constraint

Parameters

scip	SCIP data structure
cons	constraint

SCIP_VAR** SCIPgetVarsSOS2	(	SCIP *	scip,
		SCIP_CONS *	cons
	)

gets array of variables in SOS2 constraint

Parameters

scip	SCIP data structure
cons	constraint data

SCIP_Real* SCIPgetWeightsSOS2	(	SCIP *	scip,
		SCIP_CONS *	cons
	)

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

Parameters

scip	SCIP data structure
cons	constraint data

SCIP

Detailed Description

Functions

Function Documentation