cons_xor.h

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/*                                                                           */
/*                  This file is part of the program and library             */
/*         SCIP --- Solving Constraint Integer Programs                      */
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/*    Copyright (C) 2002-2022 Konrad-Zuse-Zentrum                            */
/*                            fuer Informationstechnik Berlin                */
/*                                                                           */
/*  SCIP is distributed under the terms of the ZIB Academic License.         */
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/**@file   cons_xor.h
 * @ingroup CONSHDLRS
 * @brief  Constraint handler for XOR constraints,  \f$rhs = x_1 \oplus x_2 \oplus \dots  \oplus x_n\f$
 * @author Tobias Achterberg
 * @author Stefan Heinz
 * @author Michael Winkler
 *
 */

/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/

#ifndef __SCIP_CONS_XOR_H__
#define __SCIP_CONS_XOR_H__


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

#ifdef __cplusplus
extern "C" {
#endif

/** creates the handler for xor constraints and includes it in SCIP
 *
 * @ingroup ConshdlrIncludes
 * */
SCIP_EXPORT
SCIP_RETCODE SCIPincludeConshdlrXor(
   SCIP*                 scip                /**< SCIP data structure */
   );

/**@addtogroup CONSHDLRS
 *
 * @{
 *
 * @name XOR Constraints
 *
 * @{
 *
 * This constraint handler deals with "xor" constraint. These are constraint of the form:
 *
 * \f[
 *    rhs = x_1 \oplus x_2 \oplus \dots  \oplus x_n
 * \f]
 *
 * where \f$x_i\f$ is a binary variable for all \f$i\f$ and \f$rhs\f$ is bool. The variables \f$x\f$'s are called
 * operators. This constraint is satisfied if \f$rhs\f$ is TRUE and an odd number of the operators are TRUE or if the
 * \f$rhs\f$ is FALSE and a even number of operators are TRUE. Hence, if the sum of \f$rhs\f$ and operators is even.
 */

/** creates and captures an xor constraint
 *
 *  @note the constraint gets captured, hence at one point you have to release it using the method SCIPreleaseCons()
 */
SCIP_EXPORT
SCIP_RETCODE SCIPcreateConsXor(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS**           cons,               /**< pointer to hold the created constraint */
   const char*           name,               /**< name of constraint */
   SCIP_Bool             rhs,                /**< right hand side of the constraint */
   int                   nvars,              /**< number of operator variables in the constraint */
   SCIP_VAR**            vars,               /**< array with operator variables of constraint */
   SCIP_Bool             initial,            /**< should the LP relaxation of constraint be in the initial LP?
                                              *   Usually set to TRUE. Set to FALSE for 'lazy constraints'. */
   SCIP_Bool             separate,           /**< should the constraint be separated during LP processing?
                                              *   Usually set to TRUE. */
   SCIP_Bool             enforce,            /**< should the constraint be enforced during node processing?
                                              *   TRUE for model constraints, FALSE for additional, redundant constraints. */
   SCIP_Bool             check,              /**< should the constraint be checked for feasibility?
                                              *   TRUE for model constraints, FALSE for additional, redundant constraints. */
   SCIP_Bool             propagate,          /**< should the constraint be propagated during node processing?
                                              *   Usually set to TRUE. */
   SCIP_Bool             local,              /**< is constraint only valid locally?
                                              *   Usually set to FALSE. Has to be set to TRUE, e.g., for branching constraints. */
   SCIP_Bool             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. */
   SCIP_Bool             dynamic,            /**< is constraint subject to aging?
                                              *   Usually set to FALSE. Set to TRUE for own cuts which
                                              *   are separated as constraints. */
   SCIP_Bool             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'. */
   SCIP_Bool             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. */
   );

/** 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 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()
 */
SCIP_EXPORT
SCIP_RETCODE SCIPcreateConsBasicXor(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS**           cons,               /**< pointer to hold the created constraint */
   const char*           name,               /**< name of constraint */
   SCIP_Bool             rhs,                /**< right hand side of the constraint */
   int                   nvars,              /**< number of operator variables in the constraint */
   SCIP_VAR**            vars                /**< array with operator variables of constraint */
   );

/** gets number of variables in xor constraint */
SCIP_EXPORT
int SCIPgetNVarsXor(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons                /**< constraint data */
   );

/** gets array of variables in xor constraint */
SCIP_EXPORT
SCIP_VAR** SCIPgetVarsXor(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons                /**< constraint data */
   );

/** gets integer variable in xor constraint */
SCIP_EXPORT
SCIP_VAR* SCIPgetIntVarXor(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons                /**< constraint data */
   );

/** gets the right hand side of the xor constraint */
SCIP_EXPORT
SCIP_Bool SCIPgetRhsXor(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons                /**< constraint data */
   );

/** @} */

/** @} */

#ifdef __cplusplus
}
#endif

#endif