cons_sos2.h

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/**@file   cons_sos2.h
 * @ingroup CONSHDLRS
 * @brief  constraint handler for SOS type 2 constraints
 * @author Marc Pfetsch
 *
 */

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

#ifndef __SCIP_CONS_SOS2_H__
#define __SCIP_CONS_SOS2_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 SOS2 constraints and includes it in SCIP
 *
 * @ingroup ConshdlrIncludes
 * */
SCIP_EXPORT
SCIP_RETCODE SCIPincludeConshdlrSOS2(
   SCIP*                 scip                /**< SCIP data structure */
   );

/**@addtogroup CONSHDLRS
 *
 * @{
 *
 * @name Specially Ordered Set (SOS) Type 2 Constraints
 *
 * @{
 *
 * 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.
 */

/** 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()
 */
SCIP_EXPORT
SCIP_RETCODE SCIPcreateConsSOS2(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS**           cons,               /**< pointer to hold the created constraint */
   const char*           name,               /**< name of constraint */
   int                   nvars,              /**< number of variables in the constraint */
   SCIP_VAR**            vars,               /**< array with variables of constraint entries */
   SCIP_Real*            weights,            /**< weights determining the variable order, or NULL if natural order should be used */
   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             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 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()
 */
SCIP_EXPORT
SCIP_RETCODE SCIPcreateConsBasicSOS2(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS**           cons,               /**< pointer to hold the created constraint */
   const char*           name,               /**< name of constraint */
   int                   nvars,              /**< number of variables in the constraint */
   SCIP_VAR**            vars,               /**< array with variables of constraint entries */
   SCIP_Real*            weights             /**< weights determining the variable order, or NULL if natural order should be used */
   );

/** adds variable to SOS2 constraint, the position is determined by the given weight */
SCIP_EXPORT
SCIP_RETCODE SCIPaddVarSOS2(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< constraint */
   SCIP_VAR*             var,                /**< variable to add to the constraint */
   SCIP_Real             weight              /**< weight determining position of variable */
   );

/** appends variable to SOS2 constraint */
SCIP_EXPORT
SCIP_RETCODE SCIPappendVarSOS2(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< constraint */
   SCIP_VAR*             var                 /**< variable to add to the constraint */
   );

/** gets number of variables in SOS2 constraint */
SCIP_EXPORT
int SCIPgetNVarsSOS2(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons                /**< constraint */
   );

/** gets array of variables in SOS2 constraint */
SCIP_EXPORT
SCIP_VAR** SCIPgetVarsSOS2(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons                /**< constraint data */
   );

/** gets array of weights in SOS2 constraint (or NULL if not existent) */
SCIP_EXPORT
SCIP_Real* SCIPgetWeightsSOS2(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons                /**< constraint data */
   );

/** @} */

/** @} */

#ifdef __cplusplus
}
#endif

#endif