Scippy

SCIP

Solving Constraint Integer Programs

type_cons.h
Go to the documentation of this file.
1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
2 /* */
3 /* This file is part of the program and library */
4 /* SCIP --- Solving Constraint Integer Programs */
5 /* */
6 /* Copyright (C) 2002-2016 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 email to scip@zib.de. */
13 /* */
14 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
15 
16 /**@file type_cons.h
17  * @ingroup TYPEDEFINITIONS
18  * @brief type definitions for constraints and constraint handlers
19  * @author Tobias Achterberg
20  * @author Stefan Heinz
21  *
22  * This file defines the interface for constraint handlers implemented in C.
23  *
24  * - \ref CONS "Instructions for implementing a constraint handler"
25  * - \ref CONSHDLRS "List of available constraint handlers"
26  * - \ref scip::ObjConshdlr "C++ wrapper class"
27  */
28 
29 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
30 
31 #ifndef __SCIP_TYPE_CONS_H__
32 #define __SCIP_TYPE_CONS_H__
33 
34 #include "scip/def.h"
35 #include "scip/type_retcode.h"
36 #include "scip/type_result.h"
37 #include "scip/type_var.h"
38 #include "scip/type_sol.h"
39 #include "scip/type_scip.h"
40 #include "scip/type_timing.h"
41 #include "scip/type_heur.h"
42 
43 #ifdef __cplusplus
44 extern "C" {
45 #endif
46 
47 typedef struct SCIP_Conshdlr SCIP_CONSHDLR; /**< constraint handler for a specific constraint type */
48 typedef struct SCIP_Cons SCIP_CONS; /**< constraint data structure */
49 typedef struct SCIP_ConshdlrData SCIP_CONSHDLRDATA; /**< constraint handler data */
50 typedef struct SCIP_ConsData SCIP_CONSDATA; /**< locally defined constraint type specific data */
51 typedef struct SCIP_ConsSetChg SCIP_CONSSETCHG; /**< tracks additions and removals of the set of active constraints */
52 
53 /** copy method for constraint handler plugins (called when SCIP copies plugins)
54  *
55  * If the copy process was a one to one the valid pointer can set to TRUE. Otherwise, you have to set this pointer to
56  * FALSE. In case all problem defining objects (constraint handlers and variable pricers) return a valid TRUE for all
57  * their copying calls, SCIP assumes that it is a overall one to one copy of the original instance. In this case any
58  * reductions made in the copied SCIP instance can be transfer to the original SCIP instance. If the valid pointer is
59  * set to TRUE and it was not one to one copy, it might happen that optimal solutions are cut off.
60  *
61  * input:
62  * - scip : SCIP main data structure
63  * - conshdlr : the constraint handler itself
64  * - valid : was the copying process valid?
65  */
66 #define SCIP_DECL_CONSHDLRCOPY(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_Bool* valid)
67 
68 /** destructor of constraint handler to free constraint handler data (called when SCIP is exiting)
69  *
70  * input:
71  * - scip : SCIP main data structure
72  * - conshdlr : the constraint handler itself
73  */
74 #define SCIP_DECL_CONSFREE(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr)
75 
76 /** initialization method of constraint handler (called after problem was transformed)
77  *
78  * input:
79  * - scip : SCIP main data structure
80  * - conshdlr : the constraint handler itself
81  * - conss : array of constraints in transformed problem
82  * - nconss : number of constraints in transformed problem
83  */
84 #define SCIP_DECL_CONSINIT(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, int nconss)
85 
86 /** deinitialization method of constraint handler (called before transformed problem is freed)
87  *
88  * input:
89  * - scip : SCIP main data structure
90  * - conshdlr : the constraint handler itself
91  * - conss : array of constraints in transformed problem
92  * - nconss : number of constraints in transformed problem
93  */
94 #define SCIP_DECL_CONSEXIT(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, int nconss)
95 
96 /** presolving initialization method of constraint handler (called when presolving is about to begin)
97  *
98  * This method is called when the presolving process is about to begin, even if presolving is turned off.
99  * The constraint handler may use this call to initialize its data structures.
100  *
101  * Necessary modifications that have to be performed even if presolving is turned off should be done here or in the
102  * presolving deinitialization call (SCIP_DECL_CONSEXITPRE()).
103  *
104  * @note Note that the constraint array might contain constraints that were created but not added to the problem.
105  * Constraints that are not added, i.e., for which SCIPconsIsAdded() returns FALSE, cannot be used for problem
106  * reductions.
107  *
108  * input:
109  * - scip : SCIP main data structure
110  * - conshdlr : the constraint handler itself
111  * - conss : array of constraints in transformed problem
112  * - nconss : number of constraints in transformed problem
113  */
114 #define SCIP_DECL_CONSINITPRE(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, int nconss)
115 
116 /** presolving deinitialization method of constraint handler (called after presolving has been finished)
117  *
118  * This method is called after the presolving has been finished, even if presolving is turned off.
119  * The constraint handler may use this call e.g. to clean up or modify its data structures.
120  *
121  * Necessary modifications that have to be performed even if presolving is turned off should be done here or in the
122  * presolving initialization call (SCIP_DECL_CONSINITPRE()).
123  *
124  * Besides necessary modifications and clean up, no time consuming operations should be performed, especially if the
125  * problem has already been solved. Use the method SCIPgetStatus(), which in this case returns SCIP_STATUS_OPTIMAL,
126  * SCIP_STATUS_INFEASIBLE, SCIP_STATUS_UNBOUNDED, or SCIP_STATUS_INFORUNBD.
127  *
128  * @note Note that the constraint array might contain constraints that were created but not added to the problem.
129  * Constraints that are not added, i.e., for which SCIPconsIsAdded() returns FALSE, cannot be used for problem
130  * reductions.
131  *
132  * input:
133  * - scip : SCIP main data structure
134  * - conshdlr : the constraint handler itself
135  * - conss : final array of constraints in transformed problem
136  * - nconss : final number of constraints in transformed problem
137  */
138 #define SCIP_DECL_CONSEXITPRE(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, int nconss)
139 
140 /** solving process initialization method of constraint handler (called when branch and bound process is about to begin)
141  *
142  * This method is called when the presolving was finished and the branch and bound process is about to begin.
143  * The constraint handler may use this call to initialize its branch and bound specific data.
144  *
145  * Besides necessary modifications and clean up, no time consuming operations should be performed, especially if the
146  * problem has already been solved. Use the method SCIPgetStatus(), which in this case returns SCIP_STATUS_OPTIMAL,
147  * SCIP_STATUS_INFEASIBLE, SCIP_STATUS_UNBOUNDED, or SCIP_STATUS_INFORUNBD.
148  *
149  * @note Note that the constraint array might contain constraints that were created but not added to the problem.
150  * Constraints that are not added, i.e., for which SCIPconsIsAdded() returns FALSE, cannot be used for problem
151  * reductions.
152  *
153  * input:
154  * - scip : SCIP main data structure
155  * - conshdlr : the constraint handler itself
156  * - conss : array of constraints of the constraint handler
157  * - nconss : number of constraints of the constraint handler
158  */
159 #define SCIP_DECL_CONSINITSOL(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, int nconss)
160 
161 /** solving process deinitialization method of constraint handler (called before branch and bound process data is freed)
162  *
163  * This method is called before the branch and bound process is freed.
164  * The constraint handler should use this call to clean up its branch and bound data, in particular to release
165  * all LP rows that he has created or captured.
166  *
167  * input:
168  * - scip : SCIP main data structure
169  * - conshdlr : the constraint handler itself
170  * - conss : array of constraints of the constraint handler
171  * - nconss : number of constraints of the constraint handler
172  * - restart : was this exit solve call triggered by a restart?
173  */
174 #define SCIP_DECL_CONSEXITSOL(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, int nconss, SCIP_Bool restart)
175 
176 /** frees specific constraint data
177  *
178  * @warning There may exist unprocessed events. For example, a variable's bound may have been already changed, but the
179  * corresponding bound change event was not yet processed.
180  *
181  * input:
182  * - scip : SCIP main data structure
183  * - conshdlr : the constraint handler itself
184  * - cons : the constraint belonging to the constraint data
185  * - consdata : pointer to the constraint data to free
186  */
187 #define SCIP_DECL_CONSDELETE(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS* cons, SCIP_CONSDATA** consdata)
188 
189 /** transforms constraint data into data belonging to the transformed problem
190  *
191  * input:
192  * - scip : SCIP main data structure
193  * - conshdlr : the constraint handler itself
194  * - sourcecons : source constraint to transform
195  * - targetcons : pointer to store created target constraint
196  */
197 #define SCIP_DECL_CONSTRANS(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS* sourcecons, SCIP_CONS** targetcons)
198 
199 /** LP initialization method of constraint handler (called before the initial LP relaxation at a node is solved)
200  *
201  * Puts the LP relaxations of all "initial" constraints into the LP. The method should put a canonic LP relaxation
202  * of all given constraints to the LP with calls to SCIPaddCut().
203  *
204  * input:
205  * - scip : SCIP main data structure
206  * - conshdlr : the constraint handler itself
207  * - conss : array of constraints to process
208  * - nconss : number of constraints to process
209  */
210 #define SCIP_DECL_CONSINITLP(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, int nconss)
211 
212 /** separation method of constraint handler for LP solution
213  *
214  * Separates all constraints of the constraint handler. The method is called in the LP solution loop,
215  * which means that a valid LP solution exists.
216  *
217  * The first nusefulconss constraints are the ones, that are identified to likely be violated. The separation
218  * method should process only the useful constraints in most runs, and only occasionally the remaining
219  * nconss - nusefulconss constraints.
220  *
221  * input:
222  * - scip : SCIP main data structure
223  * - conshdlr : the constraint handler itself
224  * - conss : array of constraints to process
225  * - nconss : number of constraints to process
226  * - nusefulconss : number of useful (non-obsolete) constraints to process
227  * - result : pointer to store the result of the separation call
228  *
229  * possible return values for *result (if more than one applies, the first in the list should be used):
230  * - SCIP_CUTOFF : the node is infeasible in the variable's bounds and can be cut off
231  * - SCIP_CONSADDED : an additional constraint was generated
232  * - SCIP_REDUCEDDOM : a variable's domain was reduced
233  * - SCIP_SEPARATED : a cutting plane was generated
234  * - SCIP_NEWROUND : a cutting plane was generated and a new separation round should immediately start
235  * - SCIP_DIDNOTFIND : the separator searched, but did not find domain reductions, cutting planes, or cut constraints
236  * - SCIP_DIDNOTRUN : the separator was skipped
237  * - SCIP_DELAYED : the separator was skipped, but should be called again
238  */
239 #define SCIP_DECL_CONSSEPALP(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, \
240  int nconss, int nusefulconss, SCIP_RESULT* result)
241 
242 /** separation method of constraint handler for arbitrary primal solution
243  *
244  * Separates all constraints of the constraint handler. The method is called outside the LP solution loop (e.g., by
245  * a relaxator or a primal heuristic), which means that there is no valid LP solution.
246  * Instead, the method should produce cuts that separate the given solution.
247  *
248  * The first nusefulconss constraints are the ones, that are identified to likely be violated. The separation
249  * method should process only the useful constraints in most runs, and only occasionally the remaining
250  * nconss - nusefulconss constraints.
251  *
252  * input:
253  * - scip : SCIP main data structure
254  * - conshdlr : the constraint handler itself
255  * - conss : array of constraints to process
256  * - nconss : number of constraints to process
257  * - nusefulconss : number of useful (non-obsolete) constraints to process
258  * - sol : primal solution that should be separated
259  * - result : pointer to store the result of the separation call
260  *
261  * possible return values for *result (if more than one applies, the first in the list should be used):
262  * - SCIP_CUTOFF : the node is infeasible in the variable's bounds and can be cut off
263  * - SCIP_CONSADDED : an additional constraint was generated
264  * - SCIP_REDUCEDDOM : a variable's domain was reduced
265  * - SCIP_SEPARATED : a cutting plane was generated
266  * - SCIP_NEWROUND : a cutting plane was generated and a new separation round should immediately start
267  * - SCIP_DIDNOTFIND : the separator searched, but did not find domain reductions, cutting planes, or cut constraints
268  * - SCIP_DIDNOTRUN : the separator was skipped
269  * - SCIP_DELAYED : the separator was skipped, but should be called again
270  */
271 #define SCIP_DECL_CONSSEPASOL(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, \
272  int nconss, int nusefulconss, SCIP_SOL* sol, SCIP_RESULT* result)
273 
274 /** constraint enforcing method of constraint handler for LP solutions
275  *
276  * The method is called at the end of the node processing loop for a node where the LP was solved.
277  * The LP solution has to be checked for feasibility. If possible, an infeasibility should be resolved by
278  * branching, reducing a variable's domain to exclude the solution or separating the solution with a valid
279  * cutting plane.
280  *
281  * The enforcing methods of the active constraint handlers are called in decreasing order of their enforcing
282  * priorities until the first constraint handler returned with the value SCIP_CUTOFF, SCIP_SEPARATED,
283  * SCIP_REDUCEDDOM, SCIP_CONSADDED, or SCIP_BRANCHED.
284  * The integrality constraint handler has an enforcing priority of zero. A constraint handler which can
285  * (or wants) to enforce its constraints only for integral solutions should have a negative enforcing priority
286  * (e.g. the alldiff-constraint can only operate on integral solutions).
287  * A constraint handler which wants to incorporate its own branching strategy even on non-integral
288  * solutions must have an enforcing priority greater than zero (e.g. the SOS-constraint incorporates
289  * SOS-branching on non-integral solutions).
290  *
291  * The first nusefulconss constraints are the ones, that are identified to likely be violated. The enforcing
292  * method should process the useful constraints first. The other nconss - nusefulconss constraints should only
293  * be enforced, if no violation was found in the useful constraints.
294  *
295  * input:
296  * - scip : SCIP main data structure
297  * - conshdlr : the constraint handler itself
298  * - conss : array of constraints to process
299  * - nconss : number of constraints to process
300  * - nusefulconss : number of useful (non-obsolete) constraints to process
301  * - solinfeasible : was the solution already declared infeasible by a constraint handler?
302  * - result : pointer to store the result of the enforcing call
303  *
304  * possible return values for *result (if more than one applies, the first in the list should be used):
305  * - SCIP_CUTOFF : the node is infeasible in the variable's bounds and can be cut off
306  * - SCIP_CONSADDED : an additional constraint was generated
307  * - SCIP_REDUCEDDOM : a variable's domain was reduced
308  * - SCIP_SEPARATED : a cutting plane was generated
309  * - SCIP_BRANCHED : no changes were made to the problem, but a branching was applied to resolve an infeasibility
310  * - SCIP_INFEASIBLE : at least one constraint is infeasible, but it was not resolved
311  * - SCIP_FEASIBLE : all constraints of the handler are feasible
312  */
313 #define SCIP_DECL_CONSENFOLP(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, int nconss, int nusefulconss, \
314  SCIP_Bool solinfeasible, SCIP_RESULT* result)
315 
316 /** constraint enforcing method of constraint handler for pseudo solutions
317  *
318  * The method is called at the end of the node processing loop for a node where the LP was not solved.
319  * The pseudo solution has to be checked for feasibility. If possible, an infeasibility should be resolved by
320  * branching, reducing a variable's domain to exclude the solution or adding an additional constraint.
321  * Separation is not possible, since the LP is not processed at the current node. All LP informations like
322  * LP solution, slack values, or reduced costs are invalid and must not be accessed.
323  *
324  * Like in the enforcing method for LP solutions, the enforcing methods of the active constraint handlers are
325  * called in decreasing order of their enforcing priorities until the first constraint handler returned with
326  * the value SCIP_CUTOFF, SCIP_REDUCEDDOM, SCIP_CONSADDED, SCIP_BRANCHED, or SCIP_SOLVELP.
327  *
328  * The first nusefulconss constraints are the ones, that are identified to likely be violated. The enforcing
329  * method should process the useful constraints first. The other nconss - nusefulconss constraints should only
330  * be enforced, if no violation was found in the useful constraints.
331  *
332  * If the pseudo solution's objective value is lower than the lower bound of the node, it cannot be feasible
333  * and the enforcing method may skip it's check and set *result to SCIP_DIDNOTRUN. However, it can also process
334  * its constraints and return any other possible result code.
335  *
336  * input:
337  * - scip : SCIP main data structure
338  * - conshdlr : the constraint handler itself
339  * - conss : array of constraints to process
340  * - nconss : number of constraints to process
341  * - nusefulconss : number of useful (non-obsolete) constraints to process
342  * - solinfeasible : was the solution already declared infeasible by a constraint handler?
343  * - objinfeasible : is the solution infeasible anyway due to violating lower objective bound?
344  * - result : pointer to store the result of the enforcing call
345  *
346  * possible return values for *result (if more than one applies, the first in the list should be used):
347  * - SCIP_CUTOFF : the node is infeasible in the variable's bounds and can be cut off
348  * - SCIP_CONSADDED : an additional constraint was generated
349  * - SCIP_REDUCEDDOM : a variable's domain was reduced
350  * - SCIP_BRANCHED : no changes were made to the problem, but a branching was applied to resolve an infeasibility
351  * - SCIP_SOLVELP : at least one constraint is infeasible, and this can only be resolved by solving the LP
352  * - SCIP_INFEASIBLE : at least one constraint is infeasible, but it was not resolved
353  * - SCIP_FEASIBLE : all constraints of the handler are feasible
354  * - SCIP_DIDNOTRUN : the enforcement was skipped (only possible, if objinfeasible is true)
355  */
356 #define SCIP_DECL_CONSENFOPS(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, int nconss, int nusefulconss, \
357  SCIP_Bool solinfeasible, SCIP_Bool objinfeasible, SCIP_RESULT* result)
358 
359 /** feasibility check method of constraint handler for integral solutions
360  *
361  * The given solution has to be checked for feasibility.
362  *
363  * The check methods of the active constraint handlers are called in decreasing order of their check
364  * priorities until the first constraint handler returned with the result SCIP_INFEASIBLE.
365  * The integrality constraint handler has a check priority of zero. A constraint handler which can
366  * (or wants) to check its constraints only for integral solutions should have a negative check priority
367  * (e.g. the alldiff-constraint can only operate on integral solutions).
368  * A constraint handler which wants to check feasibility even on non-integral solutions must have a
369  * check priority greater than zero (e.g. if the check is much faster than testing all variables for
370  * integrality).
371  *
372  * In some cases, integrality conditions or rows of the current LP don't have to be checked, because their
373  * feasibility is already checked or implicitly given. In these cases, 'checkintegrality' or
374  * 'checklprows' is FALSE.
375  *
376  * input:
377  * - scip : SCIP main data structure
378  * - conshdlr : the constraint handler itself
379  * - conss : array of constraints to process
380  * - nconss : number of constraints to process
381  * - sol : the solution to check feasibility for
382  * - checkintegrality: Has integrality to be checked?
383  * - checklprows : Do constraints represented by rows in the current LP have to be checked?
384  * - printreason : Should the reason for the violation be printed?
385  * - result : pointer to store the result of the feasibility checking call
386  *
387  * possible return values for *result:
388  * - SCIP_INFEASIBLE : at least one constraint of the handler is infeasible
389  * - SCIP_FEASIBLE : all constraints of the handler are feasible
390  */
391 #define SCIP_DECL_CONSCHECK(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, int nconss, SCIP_SOL* sol, \
392  SCIP_Bool checkintegrality, SCIP_Bool checklprows, SCIP_Bool printreason, SCIP_RESULT* result)
393 
394 /** domain propagation method of constraint handler
395  *
396  * The first nusefulconss constraints are the ones, that are identified to likely be violated. The propagation
397  * method should process only the useful constraints in most runs, and only occasionally the remaining
398  * nconss - nusefulconss constraints.
399  *
400  * @note if the constraint handler uses dual information in propagation it is nesassary to check via calling
401  * SCIPallowDualReds and SCIPallowObjProp if dual reductions and propgation with the current cutoff bound, resp.,
402  * are allowed.
403  *
404  * input:
405  * - scip : SCIP main data structure
406  * - conshdlr : the constraint handler itself
407  * - conss : array of constraints to process
408  * - nconss : number of constraints to process
409  * - nusefulconss : number of useful (non-obsolete) constraints to process
410  * - nmarkedconss : number of constraints which are marked to be definitely propagated
411  * - proptiming : current point in the node solving loop
412  * - result : pointer to store the result of the propagation call
413  *
414  * possible return values for *result:
415  * - SCIP_CUTOFF : the node is infeasible in the variable's bounds and can be cut off
416  * - SCIP_REDUCEDDOM : at least one domain reduction was found
417  * - SCIP_DIDNOTFIND : the propagator searched but did not find any domain reductions
418  * - SCIP_DIDNOTRUN : the propagator was skipped
419  * - SCIP_DELAYED : the propagator was skipped, but should be called again
420  */
421 #define SCIP_DECL_CONSPROP(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, int nconss, int nusefulconss, int nmarkedconss, \
422  SCIP_PROPTIMING proptiming, SCIP_RESULT* result)
423 
424 /** presolving method of constraint handler
425  *
426  * The presolver should go through the variables and constraints and tighten the domains or
427  * constraints. Each tightening should increase the given total number of changes.
428  *
429  * input:
430  * - scip : SCIP main data structure
431  * - conshdlr : the constraint handler itself
432  * - conss : array of constraints to process
433  * - nconss : number of constraints to process
434  * - nrounds : number of presolving rounds already done
435  * - presoltiming : current presolving timing
436  * - nnewfixedvars : number of variables fixed since the last call to the presolving method
437  * - nnewaggrvars : number of variables aggregated since the last call to the presolving method
438  * - nnewchgvartypes : number of variable type changes since the last call to the presolving method
439  * - nnewchgbds : number of variable bounds tightened since the last call to the presolving method
440  * - nnewholes : number of domain holes added since the last call to the presolving method
441  * - nnewdelconss : number of deleted constraints since the last call to the presolving method
442  * - nnewaddconss : number of added constraints since the last call to the presolving method
443  * - nnewupgdconss : number of upgraded constraints since the last call to the presolving method
444  * - nnewchgcoefs : number of changed coefficients since the last call to the presolving method
445  * - nnewchgsides : number of changed left or right hand sides since the last call to the presolving method
446  *
447  * @note the counters state the changes since the last call including the changes of this presolving method during its
448  * call
449  *
450  * @note if the constraint handler performs dual presolving it is nesassary to check via calling SCIPallowDualReds
451  * if dual reductions are allowed.
452  *
453  * input/output:
454  * - nfixedvars : pointer to count total number of variables fixed of all presolvers
455  * - naggrvars : pointer to count total number of variables aggregated of all presolvers
456  * - nchgvartypes : pointer to count total number of variable type changes of all presolvers
457  * - nchgbds : pointer to count total number of variable bounds tightened of all presolvers
458  * - naddholes : pointer to count total number of domain holes added of all presolvers
459  * - ndelconss : pointer to count total number of deleted constraints of all presolvers
460  * - naddconss : pointer to count total number of added constraints of all presolvers
461  * - nupgdconss : pointer to count total number of upgraded constraints of all presolvers
462  * - nchgcoefs : pointer to count total number of changed coefficients of all presolvers
463  * - nchgsides : pointer to count total number of changed left/right hand sides of all presolvers
464  *
465  * @todo: implement a final round of presolving after SCIPisPresolveFinished(),
466  * therefore, duplicate counters to a "relevant for finishing presolve" version
467  *
468  * output:
469  * - result : pointer to store the result of the presolving call
470  *
471  * possible return values for *result:
472  * - SCIP_UNBOUNDED : at least one variable is not bounded by any constraint in obj. direction -> problem is unbounded
473  * - SCIP_CUTOFF : at least one constraint is infeasible in the variable's bounds -> problem is infeasible
474  * - SCIP_SUCCESS : the presolving method found a reduction
475  * - SCIP_DIDNOTFIND : the presolving method searched, but did not find a presolving change
476  * - SCIP_DIDNOTRUN : the presolving method was skipped
477  * - SCIP_DELAYED : the presolving method was skipped, but should be called again
478  */
479 #define SCIP_DECL_CONSPRESOL(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, int nconss, int nrounds, \
480  SCIP_PRESOLTIMING presoltiming, int nnewfixedvars, int nnewaggrvars, int nnewchgvartypes, int nnewchgbds, int nnewholes, \
481  int nnewdelconss, int nnewaddconss, int nnewupgdconss, int nnewchgcoefs, int nnewchgsides, \
482  int* nfixedvars, int* naggrvars, int* nchgvartypes, int* nchgbds, int* naddholes, \
483  int* ndelconss, int* naddconss, int* nupgdconss, int* nchgcoefs, int* nchgsides, SCIP_RESULT* result)
484 
485 /** propagation conflict resolving method of constraint handler
486  *
487  * This method is called during conflict analysis. If the constraint handler wants to support conflict analysis,
488  * it should call SCIPinferVarLbCons() or SCIPinferVarUbCons() in domain propagation instead of SCIPchgVarLb() or
489  * SCIPchgVarUb() in order to deduce bound changes on variables.
490  * In the SCIPinferVarLbCons() and SCIPinferVarUbCons() calls, the handler provides the constraint, that deduced the
491  * variable's bound change, and an integer value "inferinfo" that can be arbitrarily chosen.
492  * The propagation conflict resolving method can then be implemented, to provide a "reasons" for the bound
493  * changes, i.e. the bounds of variables at the time of the propagation, that forced the constraint to set the
494  * conflict variable's bound to its current value. It can use the "inferinfo" tag to identify its own propagation
495  * rule and thus identify the "reason" bounds. The bounds that form the reason of the assignment must then be provided
496  * by calls to SCIPaddConflictLb(), SCIPaddConflictUb(), SCIPaddConflictBd(), SCIPaddConflictRelaxedLb(),
497  * SCIPaddConflictRelaxedUb(), SCIPaddConflictRelaxedBd(), and/or SCIPaddConflictBinvar() in the propagation conflict
498  * resolving method.
499  *
500  * For example, the logicor constraint c = "x or y or z" fixes variable z to TRUE (i.e. changes the lower bound of z
501  * to 1.0), if both, x and y, are assigned to FALSE (i.e. if the upper bounds of these variables are 0.0). It uses
502  * SCIPinferVarLbCons(scip, z, 1.0, c, 0) to apply this assignment (an inference information tag is not needed by the
503  * constraint handler and is set to 0).
504  * In the conflict analysis, the constraint handler may be asked to resolve the lower bound change on z with
505  * constraint c, that was applied at a time given by a bound change index "bdchgidx".
506  * With a call to SCIPvarGetLbAtIndex(z, bdchgidx, TRUE), the handler can find out, that the lower bound of
507  * variable z was set to 1.0 at the given point of time, and should call SCIPaddConflictUb(scip, x, bdchgidx) and
508  * SCIPaddConflictUb(scip, y, bdchgidx) to tell SCIP, that the upper bounds of x and y at this point of time were
509  * the reason for the deduction of the lower bound of z.
510  *
511  * input:
512  * - scip : SCIP main data structure
513  * - conshdlr : the constraint handler itself
514  * - cons : the constraint that deduced the bound change of the conflict variable
515  * - infervar : the conflict variable whose bound change has to be resolved
516  * - inferinfo : the user information passed to the corresponding SCIPinferVarLbCons() or SCIPinferVarUbCons() call
517  * - boundtype : the type of the changed bound (lower or upper bound)
518  * - bdchgidx : the index of the bound change, representing the point of time where the change took place
519  * - relaxedbd : the relaxed bound which is sufficient to be explained
520  *
521  * output:
522  * - result : pointer to store the result of the propagation conflict resolving call
523  *
524  * possible return values for *result:
525  * - SCIP_SUCCESS : the conflicting bound change has been successfully resolved by adding all reason bounds
526  * - SCIP_DIDNOTFIND : the conflicting bound change could not be resolved and has to be put into the conflict set
527  *
528  * @note it is sufficient to explain/resolve the relaxed bound
529  */
530 #define SCIP_DECL_CONSRESPROP(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS* cons, \
531  SCIP_VAR* infervar, int inferinfo, SCIP_BOUNDTYPE boundtype, SCIP_BDCHGIDX* bdchgidx, SCIP_Real relaxedbd, \
532  SCIP_RESULT* result)
533 
534 /** variable rounding lock method of constraint handler
535  *
536  * This method is called, after a constraint is added or removed from the transformed problem.
537  * It should update the rounding locks of all associated variables with calls to SCIPaddVarLocks(),
538  * depending on the way, the variable is involved in the constraint:
539  * - If the constraint may get violated by decreasing the value of a variable, it should call
540  * SCIPaddVarLocks(scip, var, nlockspos, nlocksneg), saying that rounding down is potentially rendering the
541  * (positive) constraint infeasible and rounding up is potentially rendering the negation of the constraint
542  * infeasible.
543  * - If the constraint may get violated by increasing the value of a variable, it should call
544  * SCIPaddVarLocks(scip, var, nlocksneg, nlockspos), saying that rounding up is potentially rendering the
545  * constraint's negation infeasible and rounding up is potentially rendering the constraint itself
546  * infeasible.
547  * - If the constraint may get violated by changing the variable in any direction, it should call
548  * SCIPaddVarLocks(scip, var, nlockspos + nlocksneg, nlockspos + nlocksneg).
549  *
550  * Consider the linear constraint "3x -5y +2z <= 7" as an example. The variable rounding lock method of the
551  * linear constraint handler should call SCIPaddVarLocks(scip, x, nlocksneg, nlockspos),
552  * SCIPaddVarLocks(scip, y, nlockspos, nlocksneg) and SCIPaddVarLocks(scip, z, nlocksneg, nlockspos) to tell SCIP,
553  * that rounding up of x and z and rounding down of y can destroy the feasibility of the constraint, while rounding
554  * down of x and z and rounding up of y can destroy the feasibility of the constraint's negation "3x -5y +2z > 7".
555  * A linear constraint "2 <= 3x -5y +2z <= 7" should call
556  * SCIPaddVarLocks(scip, ..., nlockspos + nlocksneg, nlockspos + nlocksneg) on all variables, since rounding in both
557  * directions of each variable can destroy both the feasibility of the constraint and it's negation
558  * "3x -5y +2z < 2 or 3x -5y +2z > 7".
559  *
560  * If the constraint itself contains other constraints as sub constraints (e.g. the "or" constraint concatenation
561  * "c(x) or d(x)"), the rounding lock methods of these constraints should be called in a proper way.
562  * - If the constraint may get violated by the violation of the sub constraint c, it should call
563  * SCIPaddConsLocks(scip, c, nlockspos, nlocksneg), saying that infeasibility of c may lead to infeasibility of
564  * the (positive) constraint, and infeasibility of c's negation (i.e. feasibility of c) may lead to infeasibility
565  * of the constraint's negation (i.e. feasibility of the constraint).
566  * - If the constraint may get violated by the feasibility of the sub constraint c, it should call
567  * SCIPaddConsLocks(scip, c, nlocksneg, nlockspos), saying that infeasibility of c may lead to infeasibility of
568  * the constraint's negation (i.e. feasibility of the constraint), and infeasibility of c's negation (i.e. feasibility
569  * of c) may lead to infeasibility of the (positive) constraint.
570  * - If the constraint may get violated by any change in the feasibility of the sub constraint c, it should call
571  * SCIPaddConsLocks(scip, c, nlockspos + nlocksneg, nlockspos + nlocksneg).
572  *
573  * Consider the or concatenation "c(x) or d(x)". The variable rounding lock method of the or constraint handler
574  * should call SCIPaddConsLocks(scip, c, nlockspos, nlocksneg) and SCIPaddConsLocks(scip, d, nlockspos, nlocksneg)
575  * to tell SCIP, that infeasibility of c and d can lead to infeasibility of "c(x) or d(x)".
576  *
577  * As a second example, consider the equivalence constraint "y <-> c(x)" with variable y and constraint c. The
578  * constraint demands, that y == 1 if and only if c(x) is satisfied. The variable lock method of the corresponding
579  * constraint handler should call SCIPaddVarLocks(scip, y, nlockspos + nlocksneg, nlockspos + nlocksneg) and
580  * SCIPaddConsLocks(scip, c, nlockspos + nlocksneg, nlockspos + nlocksneg), because any modification to the
581  * value of y or to the feasibility of c can alter the feasibility of the equivalence constraint.
582  *
583  * input:
584  * - scip : SCIP main data structure
585  * - conshdlr : the constraint handler itself
586  * - cons : the constraint that should lock rounding of its variables, or NULL if the constraint handler
587  * does not need constraints
588  * - nlockspos : number of times, the roundings should be locked for the constraint (may be negative)
589  * - nlocksneg : number of times, the roundings should be locked for the constraint's negation (may be negative)
590  */
591 #define SCIP_DECL_CONSLOCK(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS* cons, int nlockspos, int nlocksneg)
592 
593 /** constraint activation notification method of constraint handler
594  *
595  * WARNING! There may exist unprocessed events. For example, a variable's bound may have been already changed, but
596  * the corresponding bound change event was not yet processed.
597  *
598  * This method is always called after a constraint of the constraint handler was activated. The constraint
599  * handler may use this call to update his own (statistical) data.
600  *
601  * input:
602  * - scip : SCIP main data structure
603  * - conshdlr : the constraint handler itself
604  * - cons : the constraint that has been activated
605  */
606 #define SCIP_DECL_CONSACTIVE(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS* cons)
607 
608 /** constraint deactivation notification method of constraint handler
609  *
610  * WARNING! There may exist unprocessed events. For example, a variable's bound may have been already changed, but
611  * the corresponding bound change event was not yet processed.
612  *
613  * This method is always called before a constraint of the constraint handler is deactivated. The constraint
614  * handler may use this call to update his own (statistical) data.
615  *
616  * input:
617  * - scip : SCIP main data structure
618  * - conshdlr : the constraint handler itself
619  * - cons : the constraint that will be deactivated
620  */
621 #define SCIP_DECL_CONSDEACTIVE(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS* cons)
622 
623 /** constraint enabling notification method of constraint handler
624  *
625  * WARNING! There may exist unprocessed events. For example, a variable's bound may have been already changed, but
626  * the corresponding bound change event was not yet processed.
627  *
628  * This method is always called after a constraint of the constraint handler was enabled. The constraint
629  * handler may use this call to update his own (statistical) data.
630  *
631  * input:
632  * - scip : SCIP main data structure
633  * - conshdlr : the constraint handler itself
634  * - cons : the constraint that has been enabled
635  */
636 #define SCIP_DECL_CONSENABLE(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS* cons)
637 
638 /** constraint disabling notification method of constraint handler
639  *
640  * WARNING! There may exist unprocessed events. For example, a variable's bound may have been already changed, but
641  * the corresponding bound change event was not yet processed.
642  *
643  * This method is always called before a constraint of the constraint handler is disabled. The constraint
644  * handler may use this call to update his own (statistical) data.
645  *
646  * input:
647  * - scip : SCIP main data structure
648  * - conshdlr : the constraint handler itself
649  * - cons : the constraint that will be disabled
650  */
651 #define SCIP_DECL_CONSDISABLE(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS* cons)
652 
653 /** variable deletion method of constraint handler
654  *
655  * This method is optinal and only of interest if you are using SCIP as a branch-and-price framework. That means, you
656  * are generating new variables during the search. If you are not doing that just define the function pointer to be
657  * NULL.
658  *
659  * If this method gets implemented you should iterate over all constraints of the constraint handler and delete all
660  * variables that were marked for deletion by SCIPdelVar().
661  *
662  * input:
663  * - scip : SCIP main data structure
664  * - conshdlr : the constraint handler itself
665  * - conss : array of constraints in transformed problem
666  * - nconss : number of constraints in transformed problem
667  */
668 #define SCIP_DECL_CONSDELVARS(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** conss, int nconss)
669 
670 /** constraint display method of constraint handler
671  *
672  * The constraint handler can store a representation of the constraint into the given text file. Use the method
673  * SCIPinfoMessage() to push a string into the file stream.
674  *
675  * @note There are several methods which help to display variables. These are SCIPwriteVarName(), SCIPwriteVarsList(),
676  * SCIPwriteVarsLinearsum(), and SCIPwriteVarsPolynomial().
677  *
678  * input: - scip : SCIP main data structure - conshdlr : the constraint handler itself - cons : the constraint that
679  * should be displayed - file : the text file to store the information into
680  *
681  */
682 #define SCIP_DECL_CONSPRINT(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS* cons, FILE* file)
683 
684 /** constraint copying method of constraint handler
685  *
686  * The constraint handler can provide a copy method which copies a constraint from one SCIP data structure into a other
687  * SCIP data structure. If a copy of a constraint is created the constraint has to be captured (The capture is usually
688  * already done due to the creation of the constraint).
689  *
690  * If the copy process was a one to one the valid pointer can set to TRUE. Otherwise, you have to set this pointer to
691  * FALSE. In case all problem defining objects (constraint handlers and variable pricers) return a valid TRUE for all
692  * their copying calls, SCIP assumes that it is a overall one to one copy of the original instance. In this case any
693  * reductions made in the copied SCIP instance can be transfer to the original SCIP instance. If the valid pointer is
694  * set to TRUE and it was not one to one copy, it might happen that optimal solutions are cut off.
695  *
696  * To get a copy of a variable in the target SCIP you should use the function SCIPgetVarCopy().
697  *
698  * input:
699  * - scip : target SCIP data structure
700  * - cons : pointer to store the created target constraint
701  * - name : name of constraint, or NULL if the name of the source constraint should be used
702  * - sourcescip : source SCIP data structure
703  * - sourceconshdlr : source constraint handler of the source SCIP
704  * - sourcecons : source constraint of the source SCIP
705  * - varmap : a SCIP_HASHMAP mapping variables of the source SCIP to corresponding variables of the target SCIP
706  * - consmap : a SCIP_HASHMAP mapping constraints of the source SCIP to corresponding constraints of the target SCIP
707  * - initial : should the LP relaxation of constraint be in the initial LP?
708  * - separate : should the constraint be separated during LP processing?
709  * - enforce : should the constraint be enforced during node processing?
710  * - check : should the constraint be checked for feasibility?
711  * - propagate : should the constraint be propagated during node processing?
712  * - local : is constraint only valid locally?
713  * - modifiable : is constraint modifiable (subject to column generation)?
714  * - dynamic : is constraint subject to aging?
715  * - removable : should the relaxation be removed from the LP due to aging or cleanup?
716  * - stickingatnode : should the constraint always be kept at the node where it was added, even
717  * if it may be moved to a more global node?
718  * - global : should a global or a local copy be created?
719  *
720  * output:
721  * - valid : pointer to store whether the copying was valid or not
722  */
723 #define SCIP_DECL_CONSCOPY(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONS** cons, const char* name, \
724  SCIP* sourcescip, SCIP_CONSHDLR* sourceconshdlr, SCIP_CONS* sourcecons, SCIP_HASHMAP* varmap, SCIP_HASHMAP* consmap, \
725  SCIP_Bool initial, SCIP_Bool separate, SCIP_Bool enforce, SCIP_Bool check, SCIP_Bool propagate, \
726  SCIP_Bool local, SCIP_Bool modifiable, SCIP_Bool dynamic, SCIP_Bool removable, SCIP_Bool stickingatnode, \
727  SCIP_Bool global, SCIP_Bool* valid)
728 
729 /** constraint parsing method of constraint handler
730  *
731  * The constraint handler can provide a callback to parse the output created by the display method
732  * (\ref SCIP_DECL_CONSPRINT) and to create a constraint out of it.
733  *
734  * @note For parsing there are several methods which are handy. Have a look at: SCIPparseVarName(),
735  * SCIPparseVarsList(), SCIPparseVarsLinearsum(), SCIPparseVarsPolynomial(), SCIPstrToRealValue(), and
736  * SCIPstrCopySection().
737  *
738  * input:
739  * - scip : SCIP main data structure
740  * - conshdlr : the constraint handler itself
741  * - cons : pointer to store the created constraint
742  * - name : name of the constraint
743  * - str : string to parse
744  * - initial : should the LP relaxation of constraint be in the initial LP?
745  * - separate : should the constraint be separated during LP processing?
746  * - enforce : should the constraint be enforced during node processing?
747  * - check : should the constraint be checked for feasibility?
748  * - propagate : should the constraint be propagated during node processing?
749  * - local : is constraint only valid locally?
750  * - modifiable : is constraint modifiable (subject to column generation)?
751  * - dynamic : is constraint subject to aging?
752  * - removable : should the relaxation be removed from the LP due to aging or cleanup?
753  * - stickingatnode : should the constraint always be kept at the node where it was added, even
754  * if it may be moved to a more global node?
755  * output:
756  * - success : pointer to store whether the parsing was successful or not
757  */
758 #define SCIP_DECL_CONSPARSE(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS** cons, \
759  const char* name, const char* str, \
760  SCIP_Bool initial, SCIP_Bool separate, SCIP_Bool enforce, SCIP_Bool check, SCIP_Bool propagate, SCIP_Bool local, \
761  SCIP_Bool modifiable, SCIP_Bool dynamic, SCIP_Bool removable, SCIP_Bool stickingatnode, SCIP_Bool* success)
762 
763 /** constraint method of constraint handler which returns the variables (if possible)
764  *
765  * The constraint handler can (this callback is optional) provide this callback to return the variables which are
766  * involved in that particular constraint. If this is possible, the variables should be copyied into the variables
767  * array and the success pointers has to be set to TRUE. Otherwise the success has to be set FALSE or the callback
768  * should not be implemented.
769  *
770  * input:
771  * - scip : SCIP main data structure
772  * - conshdlr : the constraint handler itself
773  * - cons : the constraint that should return its variable data
774  *
775  * output:
776  * - vars : array to store/copy the involved variables of the constraint
777  * - varssize : available slots in vars array which is needed to check if the array is large enough
778  * - success : pointer to store whether the variables are successfully copied
779  */
780 #define SCIP_DECL_CONSGETVARS(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS* cons, \
781  SCIP_VAR** vars, int varssize, SCIP_Bool* success)
782 
783 /** constraint method of constraint handler which returns the number of variables (if possible)
784  *
785  * The constraint handler can (this callback is optional) provide this callback to return the number variable which are
786  * involved in that particular constraint. If this is not possible, the success pointers has to be set to FALSE or the
787  * callback should not be implemented.
788  *
789  * input:
790  * - scip : SCIP main data structure
791  * - conshdlr : the constraint handler itself
792  * - cons : constraint for which the number of variables is wanted
793  *
794  * output:
795  * - nvars : pointer to store the number of variables
796  * - success : pointer to store whether the constraint successfully returned the number of variables
797  */
798 #define SCIP_DECL_CONSGETNVARS(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_CONS* cons, \
799  int* nvars, SCIP_Bool* success)
800 
801 /** constraint handler method to suggest dive bound changes during the generic diving algorithm
802  *
803  * This callback is used inside the various diving heuristics of SCIP and does not affect the normal branching
804  * of the actual search.
805  * The constraint handler can provide this callback to render the current solution (even more) infeasible by
806  * suggesting one or several variable bound changes. Infact,
807  * since diving heuristics do not necessarily solve LP relaxations at every probing depth, some of the variable
808  * local bounds might already be conflicting with the solution values.
809  * The solution is rendered infeasible by determining bound changes that should be applied to the next explored search node
810  * via SCIPaddDiveBoundChange().
811  * An alternative in case that the preferred bound change(s) were detected infeasible must be provided.
812  *
813  * The constraint handler must take care to only add bound changes that further shrink the variable domain.
814  *
815  * The success pointer must be used to indicate whether the constraint handler succeeded in selecting diving bound
816  * changes. The infeasible pointer should be set to TRUE if the constraint handler found a local infeasibility. If the
817  * constraint handler needs to select between several candidates, it may use the scoring mechanism of the diveset
818  * argument to control its choice.
819  *
820  *
821  *
822  * This callback is optional.
823  *
824  * @note: @p sol is usually the LP relaxation solution unless the caller of the method, usually a diving heuristic,
825  * does not solve LP relaxations at every depth
826  *
827  * input:
828  * - scip : SCIP main data structure
829  * - conshdlr : the constraint handler itself
830  * - diveset : diving settings for scoring
831  * - sol : current diving solution, usually the LP relaxation solution
832  *
833  * output:
834  * - success : pointer to store whether the constraint handler succeeded to determine dive bound changes
835  * - infeasible : pointer to store whether the constraint handler detected an infeasibility in the local node
836  */
837 #define SCIP_DECL_CONSGETDIVEBDCHGS(x) SCIP_RETCODE x (SCIP* scip, SCIP_CONSHDLR* conshdlr, SCIP_DIVESET* diveset, \
838  SCIP_SOL* sol, SCIP_Bool* success, SCIP_Bool* infeasible)
839 
840 #ifdef __cplusplus
841 }
842 #endif
843 
844 #endif
struct SCIP_Cons SCIP_CONS
Definition: type_cons.h:48
timing definitions for SCIP
type definitions for return codes for SCIP methods
struct SCIP_ConsSetChg SCIP_CONSSETCHG
Definition: type_cons.h:51
type definitions for primal heuristics
type definitions for SCIP&#39;s main datastructure
type definitions for problem variables
struct SCIP_ConsData SCIP_CONSDATA
Definition: type_cons.h:50
type definitions for storing primal CIP solutions
struct SCIP_Conshdlr SCIP_CONSHDLR
Definition: type_cons.h:47
result codes for SCIP callback methods
struct SCIP_ConshdlrData SCIP_CONSHDLRDATA
Definition: type_cons.h:49
common defines and data types used in all packages of SCIP