Scippy

SCIP

Solving Constraint Integer Programs

cons_orbitope.h
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1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
2 /* */
3 /* This file is part of the program and library */
4 /* SCIP --- Solving Constraint Integer Programs */
5 /* */
6 /* Copyright (C) 2002-2021 Konrad-Zuse-Zentrum */
7 /* fuer Informationstechnik Berlin */
8 /* */
9 /* SCIP is distributed under the terms of the ZIB Academic License. */
10 /* */
11 /* You should have received a copy of the ZIB Academic License */
12 /* along with SCIP; see the file COPYING. If not visit scipopt.org. */
13 /* */
14 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
15 
16 /**@file cons_orbitope.h
17  * @ingroup CONSHDLRS
18  * @brief constraint handler for (partitioning/packing/full) orbitope constraints w.r.t. the full symmetric group
19  * @author Timo Berthold
20  * @author Marc Pfetsch
21  * @author Christopher Hojny
22  */
23 
24 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
25 
26 #ifndef __SCIP_CONS_ORBITOPE_H__
27 #define __SCIP_CONS_ORBITOPE_H__
28 
29 #include "scip/def.h"
30 #include "scip/type_cons.h"
31 #include "scip/type_retcode.h"
32 #include "scip/type_scip.h"
33 #include "scip/type_var.h"
34 
35 #ifdef __cplusplus
36 extern "C" {
37 #endif
38 
39 
40 /** creates the handler for orbitope constraints and includes it in SCIP
41  *
42  * @ingroup ConshdlrIncludes
43  */
46  SCIP* scip /**< SCIP data structure */
47  );
48 
49 /**@addtogroup CONSHDLRS
50  *
51  * @{
52  *
53  * @name Orbitope Constraints
54  *
55  * @{
56  *
57  * This constraint handler can be used to handle symmetries in certain 0/1-programs. The principle
58  * structure is that some variables can be ordered in matrix form, such that permuting columns does
59  * not change the validity and objective function value of a solution. That is, the symmetry group
60  * of the program contains the full symmetric group obtained by permuting the columns of this
61  * matrix. These symmetries can be handled by so-called full orbitopes.
62  *
63  * Moreover, if the variables in each row are contained in set packing or partitioning
64  * constraint, these symmetries can be handled by specialized packing or partitioning orbitopes.
65  *
66  * In more mathematical terms the structure has to be as follows: There are 0/1-variables
67  * \f$x_{ij}\f$, \f$i \in \{1, \dots, p\}\f$, \f$j \in \{1, \dots, q\}\f$. The variables may be coupled
68  * through set packing or partitioning constraints:
69  * \f[
70  * \sum_{j = 1}^q x_{ij} \leq 1 \quad \mbox{or} \quad \sum_{j = 1}^q x_{ij} = 1 \quad \mbox{for all }i = 1, \ldots, p.
71  * \f]
72  * Permuting columns of \f$x\f$ does not change the validity and objective function value of any feasible solution.
73  *
74  * We distinguish whether an orbitope is a model constraint or not. If it is a model constraint, then
75  * its information are copied to subSCIPs. Otherwise, the constraint was added just for the purpose of
76  * symmetry handling and we do not copy its information to subSCIPs.
77  */
78 
79 /** type of orbitope constraint: full, packing, or partitioning orbitope */
81 {
82  SCIP_ORBITOPETYPE_FULL = 0, /**< constraint is a full orbitope constraint: rowsum(x) unrestricted */
83  SCIP_ORBITOPETYPE_PARTITIONING = 1, /**< constraint is a partitioning orbitope constraint: rowsum(x) == 1 */
84  SCIP_ORBITOPETYPE_PACKING = 2 /**< constraint is a packing orbitope constraint: rowsum(x) <= 1 */
85 };
87 
88 /** creates and captures a orbitope constraint
89  *
90  * @note the constraint gets captured, hence at one point you have to release it using the method SCIPreleaseCons()
91  */
94  SCIP* scip, /**< SCIP data structure */
95  SCIP_CONS** cons, /**< pointer to hold the created constraint */
96  const char* name, /**< name of constraint */
97  SCIP_VAR*** vars, /**< matrix of variables on which the symmetry acts */
98  SCIP_ORBITOPETYPE orbitopetype, /**< type of orbitope constraint */
99  int nspcons, /**< number of set partitioning/packing constraints <=> p */
100  int nblocks, /**< number of symmetric variable blocks <=> q */
101  SCIP_Bool resolveprop, /**< should propagation be resolved? */
102  SCIP_Bool ismodelcons, /**< whether the orbitope is a model constraint */
103  SCIP_Bool initial, /**< should the LP relaxation of constraint be in the initial LP?
104  * Usually set to TRUE. Set to FALSE for 'lazy constraints'. */
105  SCIP_Bool separate, /**< should the constraint be separated during LP processing?
106  * Usually set to TRUE. */
107  SCIP_Bool enforce, /**< should the constraint be enforced during node processing?
108  * TRUE for model constraints, FALSE for additional, redundant constraints. */
109  SCIP_Bool check, /**< should the constraint be checked for feasibility?
110  * TRUE for model constraints, FALSE for additional, redundant constraints. */
111  SCIP_Bool propagate, /**< should the constraint be propagated during node processing?
112  * Usually set to TRUE. */
113  SCIP_Bool local, /**< is constraint only valid locally?
114  * Usually set to FALSE. Has to be set to TRUE, e.g., for branching constraints. */
115  SCIP_Bool modifiable, /**< is constraint modifiable (subject to column generation)?
116  * Usually set to FALSE. In column generation applications, set to TRUE if pricing
117  * adds coefficients to this constraint. */
118  SCIP_Bool dynamic, /**< is constraint subject to aging?
119  * Usually set to FALSE. Set to TRUE for own cuts which
120  * are separated as constraints. */
121  SCIP_Bool removable, /**< should the relaxation be removed from the LP due to aging or cleanup?
122  * Usually set to FALSE. Set to TRUE for 'lazy constraints' and 'user cuts'. */
123  SCIP_Bool stickingatnode /**< should the constraint always be kept at the node where it was added, even
124  * if it may be moved to a more global node?
125  * Usually set to FALSE. Set to TRUE to for constraints that represent node data. */
126  );
127 
128 /** creates and captures an orbitope constraint
129  * in its most basic variant, i. e., with all constraint flags set to their default values, which can be set
130  * afterwards using SCIPsetConsFLAGNAME() in scip.h
131  *
132  * @see SCIPcreateConsOrbitope() for the default constraint flag configuration
133  *
134  * @note the constraint gets captured, hence at one point you have to release it using the method SCIPreleaseCons()
135  */
138  SCIP* scip, /**< SCIP data structure */
139  SCIP_CONS** cons, /**< pointer to hold the created constraint */
140  const char* name, /**< name of constraint */
141  SCIP_VAR*** vars, /**< matrix of variables on which the symmetry acts */
142  SCIP_ORBITOPETYPE orbitopetype, /**< type of orbitope constraint */
143  int nspcons, /**< number of set partitioning/packing constraints <=> p */
144  int nblocks, /**< number of symmetric variable blocks <=> q */
145  SCIP_Bool resolveprop, /**< should propagation be resolved? */
146  SCIP_Bool ismodelcons /**< whether the orbitope is a model constraint */
147  );
148 
149 /** @} */
150 
151 /** @} */
152 
153 #ifdef __cplusplus
154 }
155 #endif
156 
157 #endif
#define SCIP_EXPORT
Definition: def.h:100
enum SCIP_Retcode SCIP_RETCODE
Definition: type_retcode.h:54
type definitions for return codes for SCIP methods
SCIP_EXPORT SCIP_RETCODE SCIPcreateConsBasicOrbitope(SCIP *scip, SCIP_CONS **cons, const char *name, SCIP_VAR ***vars, SCIP_ORBITOPETYPE orbitopetype, int nspcons, int nblocks, SCIP_Bool resolveprop, SCIP_Bool ismodelcons)
type definitions for SCIP&#39;s main datastructure
enum SCIP_OrbitopeType SCIP_ORBITOPETYPE
Definition: cons_orbitope.h:86
type definitions for problem variables
#define SCIP_Bool
Definition: def.h:70
SCIP_OrbitopeType
Definition: cons_orbitope.h:80
SCIP_EXPORT SCIP_RETCODE SCIPincludeConshdlrOrbitope(SCIP *scip)
SCIP_EXPORT SCIP_RETCODE SCIPcreateConsOrbitope(SCIP *scip, SCIP_CONS **cons, const char *name, SCIP_VAR ***vars, SCIP_ORBITOPETYPE orbitopetype, int nspcons, int nblocks, SCIP_Bool resolveprop, SCIP_Bool ismodelcons, 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)
common defines and data types used in all packages of SCIP
type definitions for constraints and constraint handlers