Detailed Description

Constraint handler for "xor" constraints, $rhs = x_1 \oplus x_2 \oplus \dots \oplus x_n$ .

Author: Tobias Achterberg; Stefan Heinz; Michael Winkler

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.h.

#include "scip/scip.h"

Go to the source code of this file.

Functions
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_Bool	SCIPgetRhsXor (SCIP scip, SCIP_CONS cons)

Function Documentation

SCIP_RETCODE SCIPincludeConshdlrXor ( SCIP * scip )

creates the handler for xor constraints and includes it in SCIP

Parameters

scip	SCIP data structure

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
	)

creates and captures an xor constraint

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
rhs	right hand side of the constraint
nvars	number of operator variables in the constraint
vars	array with operator variables of constraint
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.

SCIP_RETCODE SCIPcreateConsBasicXor	(	SCIP *	scip,
		SCIP_CONS **	cons,
		const char *	name,
		SCIP_Bool	rhs,
		int	nvars,
		SCIP_VAR **	vars
	)

creates and captures an xor constraint in its most basic version, i. e., all constraint flags are set to their basic value as explained for the method SCIPcreateConsXor(); all flags can be set via SCIPsetConsFLAGNAME-methods in scip.h

See Also: SCIPcreateConsXor() for information about the basic constraint flag configuration

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
rhs	right hand side of the constraint
nvars	number of operator variables in the constraint
vars	array with operator variables of constraint

int SCIPgetNVarsXor	(	SCIP *	scip,
		SCIP_CONS *	cons
	)

gets number of variables in xor constraint

Parameters

scip	SCIP data structure
cons	constraint data

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

gets array of variables in xor constraint

Parameters

scip	SCIP data structure
cons	constraint data

SCIP_Bool SCIPgetRhsXor	(	SCIP *	scip,
		SCIP_CONS *	cons
	)

gets the right hand side of the xor constraint

Parameters

scip	SCIP data structure
cons	constraint data

SCIP

Detailed Description

Functions

Function Documentation