Scippy

SCIP

Solving Constraint Integer Programs

cons_symresack.h
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3 /* This file is part of the program and library */
4 /* SCIP --- Solving Constraint Integer Programs */
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24 
25 /**@file cons_symresack.h
26  * @ingroup CONSHDLRS
27  * @brief constraint handler for symresack constraints
28  * @author Christopher Hojny
29  *
30  */
31 
32 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
33 
34 #ifndef __SCIP_CONS_SYMRESACK_H__
35 #define __SCIP_CONS_SYMRESACK_H__
36 
37 #include "scip/def.h"
38 #include "scip/type_cons.h"
39 #include "scip/type_retcode.h"
40 #include "scip/type_scip.h"
41 #include "scip/type_var.h"
42 
43 #ifdef __cplusplus
44 extern "C" {
45 #endif
46 
47 
48 
49 /** creates the handler for symresack constraints and includes it in SCIP
50  *
51  * @ingroup ConshdlrIncludes
52  */
53 SCIP_EXPORT
54 SCIP_RETCODE SCIPincludeConshdlrSymresack(
55  SCIP* scip /**< SCIP data structure */
56  );
57 
58 /**@addtogroup CONSHDLRS
59  *
60  * @{
61  *
62  * @name Symresack Constraints
63  *
64  * @{
65  *
66  * Given a permutation that acts on the order of the variables of a (mixed) 0/1-program
67  * such that the permutation is a symmetry of the program, this constraint handler can
68  * be used to handle the symmetries corresponding to the permutation. The symmetries
69  * are handled by enforcing that a binary solution is lexicographically not smaller than
70  * its permutation. In a presolving step, we check whether the permutation acts only on
71  * binary points. Otherwise, we eliminate the non-binary variables from the permutation.
72  * Furthermore, we delete fixed points from the permutation.
73  *
74  * Moreover, the constraint handler checks whether each cycle of the permutation is
75  * contained in a set packing or partitioning constraint. In this case, the symresack
76  * is strengthened to a ppsymresack and strong symmetry handling inequalities are added during
77  * the initialization of the constraint handler.
78  *
79  * @pre The permutation is encoded by an array perm for which perm[i] = j if and only if
80  * the image of i under the permutation is j.
81  *
82  * @pre The permutation given to the constraint handler has to be a symmetry of the
83  * underlying problem. This is NOT checked by the constraint handler.
84  */
85 
86 /** creates a symmetry breaking constraint
87  *
88  * Depending on the given permutation, either an orbisack or symresack constraint
89  * is created.
90  */
91 SCIP_EXPORT
92 SCIP_RETCODE SCIPcreateSymbreakCons(
93  SCIP* scip, /**< SCIP data structure */
94  SCIP_CONS** cons, /**< pointer to hold the created constraint */
95  const char* name, /**< name of constraint */
96  int* perm, /**< permutation */
97  SCIP_VAR** vars, /**< variables */
98  int nvars, /**< number of variables in vars array */
99  SCIP_Bool ismodelcons, /**< whether the added constraint is a model constraint */
100  SCIP_Bool initial, /**< should the LP relaxation of constraint be in the initial LP?
101  * Usually set to TRUE. Set to FALSE for 'lazy constraints'. */
102  SCIP_Bool separate, /**< should the constraint be separated during LP processing?
103  * Usually set to TRUE. */
104  SCIP_Bool enforce, /**< should the constraint be enforced during node processing?
105  * TRUE for model constraints, FALSE for additional, redundant constraints. */
106  SCIP_Bool check, /**< should the constraint be checked for feasibility?
107  * TRUE for model constraints, FALSE for additional, redundant constraints. */
108  SCIP_Bool propagate, /**< should the constraint be propagated during node processing?
109  * Usually set to TRUE. */
110  SCIP_Bool local, /**< is constraint only valid locally?
111  * Usually set to FALSE. Has to be set to TRUE, e.g., for branching constraints. */
112  SCIP_Bool modifiable, /**< is constraint modifiable (subject to column generation)?
113  * Usually set to FALSE. In column generation applications, set to TRUE if pricing
114  * adds coefficients to this constraint. */
115  SCIP_Bool dynamic, /**< is constraint subject to aging?
116  * Usually set to FALSE. Set to TRUE for own cuts which
117  * are separated as constraints. */
118  SCIP_Bool removable, /**< should the relaxation be removed from the LP due to aging or cleanup?
119  * Usually set to FALSE. Set to TRUE for 'lazy constraints' and 'user cuts'. */
120  SCIP_Bool stickingatnode /**< should the constraint always be kept at the node where it was added, even
121  * if it may be moved to a more global node?
122  * Usually set to FALSE. Set to TRUE to for constraints that represent node data. */
123  );
124 
125 
126 /** creates and captures a symresack constraint
127  *
128  * @note the constraint gets captured, hence at one point you have to release it using the method SCIPreleaseCons()
129  */
130 SCIP_EXPORT
131 SCIP_RETCODE SCIPcreateConsSymresack(
132  SCIP* scip, /**< SCIP data structure */
133  SCIP_CONS** cons, /**< pointer to hold the created constraint */
134  const char* name, /**< name of constraint */
135  int* perm, /**< permutation */
136  SCIP_VAR** vars, /**< variables */
137  int nvars, /**< number of variables in vars array */
138  SCIP_Bool ismodelcons, /**< whether the symresack is a model constraint */
139  SCIP_Bool initial, /**< should the LP relaxation of constraint be in the initial LP?
140  * Usually set to TRUE. Set to FALSE for 'lazy constraints'. */
141  SCIP_Bool separate, /**< should the constraint be separated during LP processing?
142  * Usually set to TRUE. */
143  SCIP_Bool enforce, /**< should the constraint be enforced during node processing?
144  * TRUE for model constraints, FALSE for additional, redundant constraints. */
145  SCIP_Bool check, /**< should the constraint be checked for feasibility?
146  * TRUE for model constraints, FALSE for additional, redundant constraints. */
147  SCIP_Bool propagate, /**< should the constraint be propagated during node processing?
148  * Usually set to TRUE. */
149  SCIP_Bool local, /**< is constraint only valid locally?
150  * Usually set to FALSE. Has to be set to TRUE, e.g., for branching constraints. */
151  SCIP_Bool modifiable, /**< is constraint modifiable (subject to column generation)?
152  * Usually set to FALSE. In column generation applications, set to TRUE if pricing
153  * adds coefficients to this constraint. */
154  SCIP_Bool dynamic, /**< is constraint subject to aging?
155  * Usually set to FALSE. Set to TRUE for own cuts which
156  * are separated as constraints. */
157  SCIP_Bool removable, /**< should the relaxation be removed from the LP due to aging or cleanup?
158  * Usually set to FALSE. Set to TRUE for 'lazy constraints' and 'user cuts'. */
159  SCIP_Bool stickingatnode /**< should the constraint always be kept at the node where it was added, even
160  * if it may be moved to a more global node?
161  * Usually set to FALSE. Set to TRUE to for constraints that represent node data. */
162  );
163 
164 /** creates and captures a symresack constraint
165  * in its most basic variant, i.e., with all constraint flags set to their default values, which can be set
166  * afterwards using SCIPsetConsFLAGNAME() in scip.h
167  *
168  * @see SCIPcreateConsSymresack() for the default constraint flag configuration
169  *
170  * @note the constraint gets captured, hence at one point you have to release it using the method SCIPreleaseCons()
171  */
172 SCIP_EXPORT
173 SCIP_RETCODE SCIPcreateConsBasicSymresack(
174  SCIP* scip, /**< SCIP data structure */
175  SCIP_CONS** cons, /**< pointer to hold the created constraint */
176  const char* name, /**< name of constraint */
177  int* perm, /**< permutation */
178  SCIP_VAR** vars, /**< variables */
179  int nvars, /**< number of variables in vars array */
180  SCIP_Bool ismodelcons /**< whether the symresack is a model constraint */
181  );
182 
183 /** @} */
184 
185 /** @} */
186 
187 #ifdef __cplusplus
188 }
189 #endif
190 
191 #endif
SCIPcreateSymbreakCons
SCIP_RETCODE SCIPcreateSymbreakCons(SCIP *scip, SCIP_CONS **cons, const char *name, int *perm, SCIP_VAR **vars, int nvars, 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)
Definition: cons_symresack.c:1733
SCIPcreateConsBasicSymresack
SCIP_RETCODE SCIPcreateConsBasicSymresack(SCIP *scip, SCIP_CONS **cons, const char *name, int *perm, SCIP_VAR **vars, int nvars, SCIP_Bool ismodelcons)
Definition: cons_symresack.c:3211
SCIP_Var
Definition: struct_var.h:207
SCIP_RETCODE
enum SCIP_Retcode SCIP_RETCODE
Definition: type_retcode.h:63
type_retcode.h
type definitions for return codes for SCIP methods
SCIPincludeConshdlrSymresack
SCIP_RETCODE SCIPincludeConshdlrSymresack(SCIP *scip)
Definition: cons_symresack.c:3084
SCIP_Cons
Definition: struct_cons.h:46
SCIPcreateConsSymresack
SCIP_RETCODE SCIPcreateConsSymresack(SCIP *scip, SCIP_CONS **cons, const char *name, int *perm, SCIP_VAR **vars, int nvars, 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)
Definition: cons_symresack.c:3146
type_scip.h
type definitions for SCIP&#39;s main datastructure
type_var.h
type definitions for problem variables
SCIP_Bool
#define SCIP_Bool
Definition: def.h:91
def.h
common defines and data types used in all packages of SCIP
type_cons.h
type definitions for constraints and constraint handlers