Scippy

SCIP

Solving Constraint Integer Programs

heur_alns.c
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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 heur_alns.c
17  * @ingroup DEFPLUGINS_HEUR
18  * @brief Adaptive large neighborhood search heuristic that orchestrates popular LNS heuristics
19  * @author Gregor Hendel
20  */
21 
22 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
23 
24 #include "blockmemshell/memory.h"
25 #include "scip/cons_linear.h"
26 #include "scip/heur_alns.h"
27 #include "scip/heuristics.h"
29 #include "scip/pub_bandit_exp3.h"
30 #include "scip/pub_bandit.h"
31 #include "scip/pub_bandit_ucb.h"
32 #include "scip/pub_event.h"
33 #include "scip/pub_heur.h"
34 #include "scip/pub_message.h"
35 #include "scip/pub_misc.h"
36 #include "scip/pub_misc_select.h"
37 #include "scip/pub_sol.h"
38 #include "scip/pub_var.h"
39 #include "scip/scip_bandit.h"
40 #include "scip/scip_branch.h"
41 #include "scip/scip_cons.h"
42 #include "scip/scip_copy.h"
43 #include "scip/scip_event.h"
44 #include "scip/scip_general.h"
45 #include "scip/scip_heur.h"
46 #include "scip/scip_lp.h"
47 #include "scip/scip_mem.h"
48 #include "scip/scip_message.h"
49 #include "scip/scip_nodesel.h"
50 #include "scip/scip_numerics.h"
51 #include "scip/scip_param.h"
52 #include "scip/scip_prob.h"
53 #include "scip/scip_randnumgen.h"
54 #include "scip/scip_sol.h"
55 #include "scip/scip_solve.h"
56 #include "scip/scip_solvingstats.h"
57 #include "scip/scip_table.h"
58 #include "scip/scip_timing.h"
59 #include "scip/scip_tree.h"
60 #include "scip/scip_var.h"
61 #include <string.h>
62 
63 #if !defined(_WIN32) && !defined(_WIN64)
64 #include <strings.h> /*lint --e{766}*/ /* needed for strncasecmp() */
65 #endif
66 
67 #define HEUR_NAME "alns"
68 #define HEUR_DESC "Large neighborhood search heuristic that orchestrates the popular neighborhoods Local Branching, RINS, RENS, DINS etc."
69 #define HEUR_DISPCHAR SCIP_HEURDISPCHAR_LNS
70 #define HEUR_PRIORITY -1100500
71 #define HEUR_FREQ 20
72 #define HEUR_FREQOFS 0
73 #define HEUR_MAXDEPTH -1
74 #define HEUR_TIMING SCIP_HEURTIMING_AFTERNODE
75 #define HEUR_USESSUBSCIP TRUE /**< does the heuristic use a secondary SCIP instance? */
76 
77 #define NNEIGHBORHOODS 9
78 
79 /*
80  * limit parameters for sub-SCIPs
81  */
82 #define DEFAULT_NODESQUOT 0.1
83 #define DEFAULT_NODESOFFSET 500LL
84 #define DEFAULT_NSOLSLIM 3
85 #define DEFAULT_MINNODES 50LL
86 #define DEFAULT_MAXNODES 5000LL
87 #define DEFAULT_WAITINGNODES 25LL /**< number of nodes since last incumbent solution that the heuristic should wait */
88 #define DEFAULT_TARGETNODEFACTOR 1.05
89 #define LRATEMIN 0.01 /**< lower bound for learning rate for target nodes and minimum improvement */
90 #define LPLIMFAC 4.0
91 
92 /*
93  * parameters for the minimum improvement
94  */
95 #define DEFAULT_MINIMPROVELOW 0.01
96 #define DEFAULT_MINIMPROVEHIGH 0.01
97 #define MINIMPROVEFAC 1.5
98 #define DEFAULT_STARTMINIMPROVE 0.01
99 #define DEFAULT_ADJUSTMINIMPROVE FALSE
100 #define DEFAULT_ADJUSTTARGETNODES TRUE /**< should the target nodes be dynamically adjusted? */
101 
102 /*
103  * bandit algorithm parameters
104  */
105 #define DEFAULT_BESTSOLWEIGHT 1
106 #define DEFAULT_BANDITALGO 'u' /**< the default bandit algorithm: (u)pper confidence bounds, (e)xp.3, epsilon (g)reedy */
107 #define DEFAULT_REWARDCONTROL 0.8 /**< reward control to increase the weight of the simple solution indicator and decrease the weight of the closed gap reward */
108 #define DEFAULT_SCALEBYEFFORT TRUE /**< should the reward be scaled by the effort? */
109 #define DEFAULT_RESETWEIGHTS TRUE /**< should the bandit algorithms be reset when a new problem is read? */
110 #define DEFAULT_SUBSCIPRANDSEEDS FALSE /**< should random seeds of sub-SCIPs be altered to increase diversification? */
111 #define DEFAULT_REWARDBASELINE 0.5 /**< the reward baseline to separate successful and failed calls */
112 #define DEFAULT_FIXTOL 0.1 /**< tolerance by which the fixing rate may be missed without generic fixing */
113 #define DEFAULT_UNFIXTOL 0.1 /**< tolerance by which the fixing rate may be exceeded without generic unfixing */
114 #define DEFAULT_USELOCALREDCOST FALSE /**< should local reduced costs be used for generic (un)fixing? */
115 #define DEFAULT_BETA 0.0 /**< default reward offset between 0 and 1 at every observation for exp3 */
116 
117 /*
118  * the following 3 parameters have been tuned by a simulation experiment
119  * as described in the paper.
120  */
121 #define DEFAULT_EPS 0.4685844 /**< increase exploration in epsilon-greedy bandit algorithm */
122 #define DEFAULT_ALPHA 0.0016 /**< parameter to increase the confidence width in UCB */
123 #define DEFAULT_GAMMA 0.07041455 /**< default weight between uniform (gamma ~ 1) and weight driven (gamma ~ 0) probability distribution for exp3 */
124 /*
125  * parameters to control variable fixing
126  */
127 #define DEFAULT_USEREDCOST TRUE /**< should reduced cost scores be used for variable priorization? */
128 #define DEFAULT_USEPSCOST TRUE /**< should pseudo cost scores be used for variable priorization? */
129 #define DEFAULT_USEDISTANCES TRUE /**< should distances from fixed variables be used for variable priorization */
130 #define DEFAULT_DOMOREFIXINGS TRUE /**< should the ALNS heuristic do more fixings by itself based on variable prioritization
131  * until the target fixing rate is reached? */
132 #define DEFAULT_ADJUSTFIXINGRATE TRUE /**< should the heuristic adjust the target fixing rate based on the success? */
133 #define FIXINGRATE_DECAY 0.75 /**< geometric decay for fixing rate adjustments */
134 #define FIXINGRATE_STARTINC 0.2 /**< initial increment value for fixing rate */
135 #define DEFAULT_USESUBSCIPHEURS FALSE /**< should the heuristic activate other sub-SCIP heuristics during its search? */
136 #define DEFAULT_COPYCUTS FALSE /**< should cutting planes be copied to the sub-SCIP? */
137 #define DEFAULT_REWARDFILENAME "-" /**< file name to store all rewards and the selection of the bandit */
139 /* individual random seeds */
140 #define DEFAULT_SEED 113
141 #define MUTATIONSEED 121
142 #define CROSSOVERSEED 321
144 /* individual neighborhood parameters */
145 #define DEFAULT_MINFIXINGRATE_RENS 0.3
146 #define DEFAULT_MAXFIXINGRATE_RENS 0.9
147 #define DEFAULT_ACTIVE_RENS TRUE
148 #define DEFAULT_PRIORITY_RENS 1.0
150 #define DEFAULT_MINFIXINGRATE_RINS 0.3
151 #define DEFAULT_MAXFIXINGRATE_RINS 0.9
152 #define DEFAULT_ACTIVE_RINS TRUE
153 #define DEFAULT_PRIORITY_RINS 1.0
155 #define DEFAULT_MINFIXINGRATE_MUTATION 0.3
156 #define DEFAULT_MAXFIXINGRATE_MUTATION 0.9
157 #define DEFAULT_ACTIVE_MUTATION TRUE
158 #define DEFAULT_PRIORITY_MUTATION 1.0
160 #define DEFAULT_MINFIXINGRATE_LOCALBRANCHING 0.3
161 #define DEFAULT_MAXFIXINGRATE_LOCALBRANCHING 0.9
162 #define DEFAULT_ACTIVE_LOCALBRANCHING TRUE
163 #define DEFAULT_PRIORITY_LOCALBRANCHING 1.0
165 #define DEFAULT_MINFIXINGRATE_PROXIMITY 0.3
166 #define DEFAULT_MAXFIXINGRATE_PROXIMITY 0.9
167 #define DEFAULT_ACTIVE_PROXIMITY TRUE
168 #define DEFAULT_PRIORITY_PROXIMITY 1.0
170 #define DEFAULT_MINFIXINGRATE_CROSSOVER 0.3
171 #define DEFAULT_MAXFIXINGRATE_CROSSOVER 0.9
172 #define DEFAULT_ACTIVE_CROSSOVER TRUE
173 #define DEFAULT_PRIORITY_CROSSOVER 1.0
175 #define DEFAULT_MINFIXINGRATE_ZEROOBJECTIVE 0.3
176 #define DEFAULT_MAXFIXINGRATE_ZEROOBJECTIVE 0.9
177 #define DEFAULT_ACTIVE_ZEROOBJECTIVE TRUE
178 #define DEFAULT_PRIORITY_ZEROOBJECTIVE 1.0
180 #define DEFAULT_MINFIXINGRATE_DINS 0.3
181 #define DEFAULT_MAXFIXINGRATE_DINS 0.9
182 #define DEFAULT_ACTIVE_DINS TRUE
183 #define DEFAULT_PRIORITY_DINS 1.0
185 #define DEFAULT_MINFIXINGRATE_TRUSTREGION 0.3
186 #define DEFAULT_MAXFIXINGRATE_TRUSTREGION 0.9
187 #define DEFAULT_ACTIVE_TRUSTREGION FALSE
188 #define DEFAULT_PRIORITY_TRUSTREGION 1.0
190 
191 #define DEFAULT_NSOLS_CROSSOVER 2 /**< parameter for the number of solutions that crossover should combine */
192 #define DEFAULT_NPOOLSOLS_DINS 5 /**< number of pool solutions where binary solution values must agree */
193 #define DEFAULT_VIOLPENALTY_TRUSTREGION 100.0 /**< the penalty for violating the trust region */
195 /* event handler properties */
196 #define EVENTHDLR_NAME "Alns"
197 #define EVENTHDLR_DESC "LP event handler for " HEUR_NAME " heuristic"
198 #define SCIP_EVENTTYPE_ALNS (SCIP_EVENTTYPE_LPSOLVED | SCIP_EVENTTYPE_SOLFOUND | SCIP_EVENTTYPE_BESTSOLFOUND)
200 /* properties of the ALNS neighborhood statistics table */
201 #define TABLE_NAME_NEIGHBORHOOD "neighborhood"
202 #define TABLE_DESC_NEIGHBORHOOD "ALNS neighborhood statistics"
203 #define TABLE_POSITION_NEIGHBORHOOD 12500 /**< the position of the statistics table */
204 #define TABLE_EARLIEST_STAGE_NEIGHBORHOOD SCIP_STAGE_TRANSFORMED /**< output of the statistics table is only printed from this stage onwards */
206 /*
207  * Data structures
208  */
209 
210 /*
211  * additional neighborhood data structures
212  */
213 
214 
215 typedef struct data_crossover DATA_CROSSOVER; /**< crossover neighborhood data structure */
217 typedef struct data_mutation DATA_MUTATION; /**< mutation neighborhood data structure */
219 typedef struct data_dins DATA_DINS; /**< dins neighborhood data structure */
221 typedef struct data_trustregion DATA_TRUSTREGION; /**< trustregion neighborhood data structure */
223 typedef struct NH_FixingRate NH_FIXINGRATE; /** fixing rate data structure */
225 typedef struct NH_Stats NH_STATS; /**< neighborhood statistics data structure */
227 typedef struct Nh NH; /**< neighborhood data structure */
229 
230 /*
231  * variable priorization data structure for sorting
232  */
233 typedef struct VarPrio VARPRIO;
235 /** callback to collect variable fixings of neighborhood */
236  #define DECL_VARFIXINGS(x) SCIP_RETCODE x ( \
237  SCIP* scip, /**< SCIP data structure */ \
238  NH* neighborhood, /**< ALNS neighborhood data structure */ \
239  SCIP_VAR** varbuf, /**< buffer array to collect variables to fix */\
240  SCIP_Real* valbuf, /**< buffer array to collect fixing values */ \
241  int* nfixings, /**< pointer to store the number of fixings */ \
242  SCIP_RESULT* result /**< result pointer */ \
243  )
244 
245 /** callback for subproblem changes other than variable fixings
246  *
247  * this callback can be used to further modify the subproblem by changes other than variable fixings.
248  * Typical modifications include restrictions of variable domains, the formulation of additional constraints,
249  * or changed objective coefficients.
250  *
251  * The callback should set the \p success pointer to indicate whether it was successful with its modifications or not.
252  */
253 #define DECL_CHANGESUBSCIP(x) SCIP_RETCODE x ( \
254  SCIP* sourcescip, /**< source SCIP data structure */\
255  SCIP* targetscip, /**< target SCIP data structure */\
256  NH* neighborhood, /**< ALNS neighborhood data structure */\
257  SCIP_VAR** subvars, /**< array of targetscip variables in the same order as the source SCIP variables */\
258  int* ndomchgs, /**< pointer to store the number of performed domain changes */\
259  int* nchgobjs, /**< pointer to store the number of changed objective coefficients */ \
260  int* naddedconss, /**< pointer to store the number of additional constraints */\
261  SCIP_Bool* success /**< pointer to store if the sub-MIP was successfully adjusted */\
262  )
263 
264 /** optional initialization callback for neighborhoods when a new problem is read */
265 #define DECL_NHINIT(x) SCIP_RETCODE x ( \
266  SCIP* scip, /**< SCIP data structure */ \
267  NH* neighborhood /**< neighborhood data structure */ \
268  )
269 
270 /** deinitialization callback for neighborhoods when exiting a problem */
271 #define DECL_NHEXIT(x) SCIP_RETCODE x ( \
272  SCIP* scip, /**< SCIP data structure */ \
273  NH* neighborhood /**< neighborhood data structure */ \
274  )
275 
276 /** deinitialization callback for neighborhoods before SCIP is freed */
277 #define DECL_NHFREE(x) SCIP_RETCODE x ( \
278  SCIP* scip, /**< SCIP data structure */ \
279  NH* neighborhood /**< neighborhood data structure */ \
280  )
281 
282 /** callback function to return a feasible reference solution for further fixings
283  *
284  * The reference solution should be stored in the \p solptr.
285  * The \p result pointer can be used to indicate either
286  *
287  * - SCIP_SUCCESS or
288  * - SCIP_DIDNOTFIND
289  */
290 #define DECL_NHREFSOL(x) SCIP_RETCODE x ( \
291  SCIP* scip, /**< SCIP data structure */ \
292  NH* neighborhood, /**< neighborhood data structure */ \
293  SCIP_SOL** solptr, /**< pointer to store the reference solution */ \
294  SCIP_RESULT* result /**< pointer to indicate the callback success whether a reference solution is available */ \
295  )
296 
297 /** callback function to deactivate neighborhoods on problems where they are irrelevant */
298 #define DECL_NHDEACTIVATE(x) SCIP_RETCODE x (\
299  SCIP* scip, /**< SCIP data structure */ \
300  SCIP_Bool* deactivate /**< pointer to store whether the neighborhood should be deactivated (TRUE) for an instance */ \
301  )
302 
303 /** sub-SCIP status code enumerator */
304 enum HistIndex
305 {
306  HIDX_OPT = 0, /**< sub-SCIP was solved to optimality */
307  HIDX_USR = 1, /**< sub-SCIP was user interrupted */
308  HIDX_NODELIM = 2, /**< sub-SCIP reached the node limit */
309  HIDX_STALLNODE = 3, /**< sub-SCIP reached the stall node limit */
310  HIDX_INFEAS = 4, /**< sub-SCIP was infeasible */
311  HIDX_SOLLIM = 5, /**< sub-SCIP reached the solution limit */
312  HIDX_OTHER = 6 /**< sub-SCIP reached none of the above codes */
313 };
314 typedef enum HistIndex HISTINDEX;
315 #define NHISTENTRIES 7
317 
318 /** statistics for a neighborhood */
319 struct NH_Stats
320 {
321  SCIP_CLOCK* setupclock; /**< clock for sub-SCIP setup time */
322  SCIP_CLOCK* submipclock; /**< clock for the sub-SCIP solve */
323  SCIP_Longint usednodes; /**< total number of used nodes */
324  SCIP_Real oldupperbound; /**< upper bound before the sub-SCIP started */
325  SCIP_Real newupperbound; /**< new upper bound for allrewards mode to work correctly */
326  int nruns; /**< number of runs of a neighborhood */
327  int nrunsbestsol; /**< number of runs that produced a new incumbent */
328  SCIP_Longint nsolsfound; /**< the total number of solutions found */
329  SCIP_Longint nbestsolsfound; /**< the total number of improving solutions found */
330  int nfixings; /**< the number of fixings in one run */
331  int statushist[NHISTENTRIES]; /**< array to count sub-SCIP statuses */
332 };
333 
334 
335 /** fixing rate data structure to control the amount of target fixings of a neighborhood */
336 struct NH_FixingRate
337 {
338  SCIP_Real minfixingrate; /**< the minimum fixing rate */
339  SCIP_Real targetfixingrate; /**< the current target fixing rate */
340  SCIP_Real increment; /**< the current increment by which the target fixing rate is in-/decreased */
341  SCIP_Real maxfixingrate; /**< the maximum fixing rate */
342 };
343 
344 /** neighborhood data structure with callbacks, statistics, fixing rate */
345 struct Nh
346 {
347  char* name; /**< the name of this neighborhood */
348  NH_FIXINGRATE fixingrate; /**< fixing rate for this neighborhood */
349  NH_STATS stats; /**< statistics for this neighborhood */
350  DECL_VARFIXINGS ((*varfixings)); /**< variable fixings callback for this neighborhood */
351  DECL_CHANGESUBSCIP ((*changesubscip)); /**< callback for subproblem changes other than variable fixings */
352  DECL_NHINIT ((*nhinit)); /**< initialization callback when a new problem is read */
353  DECL_NHEXIT ((*nhexit)); /**< deinitialization callback when exiting a problem */
354  DECL_NHFREE ((*nhfree)); /**< deinitialization callback before SCIP is freed */
355  DECL_NHREFSOL ((*nhrefsol)); /**< callback function to return a reference solution for further fixings, or NULL */
356  DECL_NHDEACTIVATE ((*nhdeactivate)); /**< callback function to deactivate neighborhoods on problems where they are irrelevant, or NULL if it is always active */
357  SCIP_Bool active; /**< is this neighborhood active or not? */
358  SCIP_Real priority; /**< positive call priority to initialize bandit algorithms */
359  union
360  {
361  DATA_MUTATION* mutation; /**< mutation data */
362  DATA_CROSSOVER* crossover; /**< crossover data */
363  DATA_DINS* dins; /**< dins data */
364  DATA_TRUSTREGION* trustregion; /**< trustregion data */
365  } data; /**< data object for neighborhood specific data */
366 };
367 
368 /** mutation neighborhood data structure */
369 struct data_mutation
370 {
371  SCIP_RANDNUMGEN* rng; /**< random number generator */
372 };
373 
374 /** crossover neighborhood data structure */
375 struct data_crossover
376 {
377  int nsols; /**< the number of solutions that crossover should combine */
378  SCIP_RANDNUMGEN* rng; /**< random number generator to draw from the solution pool */
379  SCIP_SOL* selsol; /**< best selected solution by crossover as reference point */
380 };
381 
382 /** dins neighborhood data structure */
383 struct data_dins
384 {
385  int npoolsols; /**< number of pool solutions where binary solution values must agree */
386 };
387 
388 struct data_trustregion
389 {
390  SCIP_Real violpenalty; /**< the penalty for violating the trust region */
391 };
392 
393 /** primal heuristic data */
394 struct SCIP_HeurData
395 {
396  NH** neighborhoods; /**< array of neighborhoods */
397  SCIP_BANDIT* bandit; /**< bandit algorithm */
398  char* rewardfilename; /**< file name to store all rewards and the selection of the bandit */
399  FILE* rewardfile; /**< reward file pointer, or NULL */
400  SCIP_Longint nodesoffset; /**< offset added to the nodes budget */
401  SCIP_Longint maxnodes; /**< maximum number of nodes in a single sub-SCIP */
402  SCIP_Longint targetnodes; /**< targeted number of nodes to start a sub-SCIP */
403  SCIP_Longint minnodes; /**< minimum number of nodes required to start a sub-SCIP */
404  SCIP_Longint usednodes; /**< total number of nodes already spent in sub-SCIPs */
405  SCIP_Longint waitingnodes; /**< number of nodes since last incumbent solution that the heuristic should wait */
406  SCIP_Real nodesquot; /**< fraction of nodes compared to the main SCIP for budget computation */
407  SCIP_Real startminimprove; /**< initial factor by which ALNS should at least improve the incumbent */
408  SCIP_Real minimprovelow; /**< lower threshold for the minimal improvement over the incumbent */
409  SCIP_Real minimprovehigh; /**< upper bound for the minimal improvement over the incumbent */
410  SCIP_Real minimprove; /**< factor by which ALNS should at least improve the incumbent */
411  SCIP_Real lplimfac; /**< limit fraction of LPs per node to interrupt sub-SCIP */
412  SCIP_Real exp3_gamma; /**< weight between uniform (gamma ~ 1) and weight driven (gamma ~ 0) probability distribution for exp3 */
413  SCIP_Real exp3_beta; /**< reward offset between 0 and 1 at every observation for exp3 */
414  SCIP_Real epsgreedy_eps; /**< increase exploration in epsilon-greedy bandit algorithm */
415  SCIP_Real ucb_alpha; /**< parameter to increase the confidence width in UCB */
416  SCIP_Real rewardcontrol; /**< reward control to increase the weight of the simple solution indicator
417  * and decrease the weight of the closed gap reward */
418  SCIP_Real targetnodefactor; /**< factor by which target node number is eventually increased */
419  SCIP_Real rewardbaseline; /**< the reward baseline to separate successful and failed calls */
420  SCIP_Real fixtol; /**< tolerance by which the fixing rate may be missed without generic fixing */
421  SCIP_Real unfixtol; /**< tolerance by which the fixing rate may be exceeded without generic unfixing */
422  int nneighborhoods; /**< number of neighborhoods */
423  int nactiveneighborhoods;/**< number of active neighborhoods */
424  int ninitneighborhoods; /**< neighborhoods that were used at least one time */
425  int nsolslim; /**< limit on the number of improving solutions in a sub-SCIP call */
426  int seed; /**< initial random seed for bandit algorithms and random decisions by neighborhoods */
427  int currneighborhood; /**< index of currently selected neighborhood */
428  int ndelayedcalls; /**< the number of delayed calls */
429  char banditalgo; /**< the bandit algorithm: (u)pper confidence bounds, (e)xp.3, epsilon (g)reedy */
430  SCIP_Bool useredcost; /**< should reduced cost scores be used for variable prioritization? */
431  SCIP_Bool usedistances; /**< should distances from fixed variables be used for variable prioritization */
432  SCIP_Bool usepscost; /**< should pseudo cost scores be used for variable prioritization? */
433  SCIP_Bool domorefixings; /**< should the ALNS heuristic do more fixings by itself based on variable prioritization
434  * until the target fixing rate is reached? */
435  SCIP_Bool adjustfixingrate; /**< should the heuristic adjust the target fixing rate based on the success? */
436  SCIP_Bool usesubscipheurs; /**< should the heuristic activate other sub-SCIP heuristics during its search? */
437  SCIP_Bool adjustminimprove; /**< should the factor by which the minimum improvement is bound be dynamically updated? */
438  SCIP_Bool adjusttargetnodes; /**< should the target nodes be dynamically adjusted? */
439  SCIP_Bool resetweights; /**< should the bandit algorithms be reset when a new problem is read? */
440  SCIP_Bool subsciprandseeds; /**< should random seeds of sub-SCIPs be altered to increase diversification? */
441  SCIP_Bool scalebyeffort; /**< should the reward be scaled by the effort? */
442  SCIP_Bool copycuts; /**< should cutting planes be copied to the sub-SCIP? */
443  SCIP_Bool uselocalredcost; /**< should local reduced costs be used for generic (un)fixing? */
444 };
445 
446 /** event handler data */
447 struct SCIP_EventData
448 {
449  SCIP_VAR** subvars; /**< the variables of the subproblem */
450  SCIP* sourcescip; /**< original SCIP data structure */
451  SCIP_HEUR* heur; /**< alns heuristic structure */
452  SCIP_Longint nodelimit; /**< node limit of the run */
453  SCIP_Real lplimfac; /**< limit fraction of LPs per node to interrupt sub-SCIP */
454  NH_STATS* runstats; /**< run statistics for the current neighborhood */
455  SCIP_Bool allrewardsmode; /**< true if solutions should only be checked for reward comparisons */
456 };
457 
458 /** represents limits for the sub-SCIP solving process */
459 struct SolveLimits
460 {
461  SCIP_Longint nodelimit; /**< maximum number of solving nodes for the sub-SCIP */
462  SCIP_Real memorylimit; /**< memory limit for the sub-SCIP */
463  SCIP_Real timelimit; /**< time limit for the sub-SCIP */
464  SCIP_Longint stallnodes; /**< maximum number of nodes without (primal) stalling */
465 };
466 
467 typedef struct SolveLimits SOLVELIMITS;
469 /** data structure that can be used for variable prioritization for additional fixings */
470 struct VarPrio
471 {
472  SCIP* scip; /**< SCIP data structure */
473  SCIP_Real* randscores; /**< random scores for prioritization */
474  int* distances; /**< breadth-first distances from already fixed variables */
475  SCIP_Real* redcostscores; /**< reduced cost scores for fixing a variable to a reference value */
476  SCIP_Real* pscostscores; /**< pseudocost scores for fixing a variable to a reference value */
477  unsigned int useredcost:1; /**< should reduced cost scores be used for variable prioritization? */
478  unsigned int usedistances:1; /**< should distances from fixed variables be used for variable prioritization */
479  unsigned int usepscost:1; /**< should pseudo cost scores be used for variable prioritization? */
480 };
481 
482 /*
483  * Local methods
484  */
485 
486 /** Reset target fixing rate */
487 static
489  SCIP* scip, /**< SCIP data structure */
490  NH_FIXINGRATE* fixingrate /**< heuristic fixing rate */
491  )
492 {
493  assert(scip != NULL);
494  assert(fixingrate != NULL);
495  fixingrate->increment = FIXINGRATE_STARTINC;
496 
497  /* always start with the most conservative value */
498  fixingrate->targetfixingrate = fixingrate->maxfixingrate;
499 
500  return SCIP_OKAY;
501 }
502 
503 /** reset the currently active neighborhood */
504 static
506  SCIP_HEURDATA* heurdata
507  )
508 {
509  assert(heurdata != NULL);
510  heurdata->currneighborhood = -1;
511  heurdata->ndelayedcalls = 0;
512 }
513 
514 /** update increment for fixing rate */
515 static
517  NH_FIXINGRATE* fx /**< fixing rate */
518  )
519 {
521  fx->increment = MAX(fx->increment, LRATEMIN);
522 }
523 
524 
525 /** increase fixing rate
526  *
527  * decrease also the rate by which the target fixing rate is adjusted
528  */
529 static
530 void increaseFixingRate(
531  NH_FIXINGRATE* fx /**< fixing rate */
532  )
533 {
534  fx->targetfixingrate += fx->increment;
535  fx->targetfixingrate = MIN(fx->targetfixingrate, fx->maxfixingrate);
536 }
537 
538 /** decrease fixing rate
539  *
540  * decrease also the rate by which the target fixing rate is adjusted
541  */
542 static
543 void decreaseFixingRate(
544  NH_FIXINGRATE* fx /**< fixing rate */
545  )
546 {
547  fx->targetfixingrate -= fx->increment;
549 }
550 
551 /** update fixing rate based on the results of the current run */
552 static
553 void updateFixingRate(
554  NH* neighborhood, /**< neighborhood */
555  SCIP_STATUS subscipstatus, /**< status of the sub-SCIP run */
556  NH_STATS* runstats /**< run statistics for this run */
557  )
558 {
559  NH_FIXINGRATE* fx;
560 
561  fx = &neighborhood->fixingrate;
562 
563  switch (subscipstatus)
564  {
565  case SCIP_STATUS_OPTIMAL:
570  /* decrease the fixing rate (make subproblem harder) */
571  decreaseFixingRate(fx);
572  break;
577  /* increase the fixing rate (make the subproblem easier) only if no solution was found */
578  if( runstats->nbestsolsfound <= 0 )
579  increaseFixingRate(fx);
580  break;
581  /* fall through cases to please lint */
582  case SCIP_STATUS_UNKNOWN:
589  default:
590  break;
591  }
592 
594 }
595 
596 /** increase target node limit */
597 static
599  SCIP_HEURDATA* heurdata /**< heuristic data */
600  )
601 {
602  heurdata->targetnodes = (SCIP_Longint)(heurdata->targetnodes * heurdata->targetnodefactor) + 1;
603 
604  /* respect upper and lower parametrized bounds on targetnodes */
605  if( heurdata->targetnodes > heurdata->maxnodes )
606  heurdata->targetnodes = heurdata->maxnodes;
607 }
608 
609 /** reset target node limit */
610 static
612  SCIP_HEURDATA* heurdata /**< heuristic data */
613  )
614 {
615  heurdata->targetnodes = heurdata->minnodes;
616 }
617 
618 /** update target node limit based on the current run results */
619 static
621  SCIP_HEURDATA* heurdata, /**< heuristic data */
622  NH_STATS* runstats, /**< statistics of the run */
623  SCIP_STATUS subscipstatus /**< status of the sub-SCIP run */
624  )
625 {
626  switch (subscipstatus)
627  {
630  /* the subproblem could be explored more */
631  if( runstats->nbestsolsfound == 0 )
632  increaseTargetNodeLimit(heurdata);
633  break;
634  case SCIP_STATUS_OPTIMAL:
639  break;
642  case SCIP_STATUS_UNKNOWN:
649  break;
650  default:
651  break;
652  }
653 }
654 
655 /** reset the minimum improvement for the sub-SCIPs */
656 static
658  SCIP_HEURDATA* heurdata /**< heuristic data */
659  )
660 {
661  assert(heurdata != NULL);
662  heurdata->minimprove = heurdata->startminimprove;
663 }
664 
665 /** increase minimum improvement for the sub-SCIPs */
666 static
668  SCIP_HEURDATA* heurdata /**< heuristic data */
669  )
670 {
671  assert(heurdata != NULL);
672 
673  heurdata->minimprove *= MINIMPROVEFAC;
674  heurdata->minimprove = MIN(heurdata->minimprove, heurdata->minimprovehigh);
675 }
676 
677 /** decrease the minimum improvement for the sub-SCIPs */
678 static
680  SCIP_HEURDATA* heurdata /**< heuristic data */
681  )
682 {
683  assert(heurdata != NULL);
684 
685  heurdata->minimprove /= MINIMPROVEFAC;
686  SCIPdebugMessage("%.4f", heurdata->minimprovelow);
687  heurdata->minimprove = MAX(heurdata->minimprove, heurdata->minimprovelow);
688 }
689 
690 /** update the minimum improvement based on the status of the sub-SCIP */
691 static
693  SCIP_HEURDATA* heurdata, /**< heuristic data */
694  SCIP_STATUS subscipstatus, /**< status of the sub-SCIP run */
695  NH_STATS* runstats /**< run statistics for this run */
696  )
697 {
698  assert(heurdata != NULL);
699 
700  /* if the sub-SCIP status was infeasible, we rather want to make the sub-SCIP easier
701  * with a smaller minimum improvement.
702  *
703  * If a solution limit was reached, we may, set it higher.
704  */
705  switch (subscipstatus)
706  {
709  /* subproblem was infeasible, probably due to the minimum improvement -> decrease minimum improvement */
710  decreaseMinimumImprovement(heurdata);
711 
712  break;
715  case SCIP_STATUS_OPTIMAL:
716  /* subproblem could be optimally solved -> try higher minimum improvement */
717  increaseMinimumImprovement(heurdata);
718  break;
722  /* subproblem was too hard, decrease minimum improvement */
723  if( runstats->nbestsolsfound <= 0 )
724  decreaseMinimumImprovement(heurdata);
725  break;
726  case SCIP_STATUS_UNKNOWN:
734  default:
735  break;
736  }
737 }
738 
739 /** Reset neighborhood statistics */
740 static
742  SCIP* scip, /**< SCIP data structure */
743  NH_STATS* stats /**< neighborhood statistics */
744  )
745 {
746  assert(scip != NULL);
747  assert(stats != NULL);
748 
749  stats->nbestsolsfound = 0;
750  stats->nruns = 0;
751  stats->nrunsbestsol = 0;
752  stats->nsolsfound = 0;
753  stats->usednodes = 0L;
754  stats->nfixings = 0L;
755 
757 
758  SCIP_CALL( SCIPresetClock(scip, stats->setupclock) );
759  SCIP_CALL( SCIPresetClock(scip, stats->submipclock) );
760 
761  return SCIP_OKAY;
762 }
763 
764 /** create a neighborhood of the specified name and include it into the ALNS heuristic */
765 static
767  SCIP* scip, /**< SCIP data structure */
768  SCIP_HEURDATA* heurdata, /**< heuristic data of the ALNS heuristic */
769  NH** neighborhood, /**< pointer to store the neighborhood */
770  const char* name, /**< name for this neighborhood */
771  SCIP_Real minfixingrate, /**< default value for minfixingrate parameter of this neighborhood */
772  SCIP_Real maxfixingrate, /**< default value for maxfixingrate parameter of this neighborhood */
773  SCIP_Bool active, /**< default value for active parameter of this neighborhood */
774  SCIP_Real priority, /**< positive call priority to initialize bandit algorithms */
775  DECL_VARFIXINGS ((*varfixings)), /**< variable fixing callback for this neighborhood, or NULL */
776  DECL_CHANGESUBSCIP ((*changesubscip)), /**< subscip changes callback for this neighborhood, or NULL */
777  DECL_NHINIT ((*nhinit)), /**< initialization callback for neighborhood, or NULL */
778  DECL_NHEXIT ((*nhexit)), /**< deinitialization callback for neighborhood, or NULL */
779  DECL_NHFREE ((*nhfree)), /**< deinitialization callback before SCIP is freed, or NULL */
780  DECL_NHREFSOL ((*nhrefsol)), /**< callback function to return a reference solution for further fixings, or NULL */
781  DECL_NHDEACTIVATE ((*nhdeactivate)) /**< callback function to deactivate neighborhoods on problems where they are irrelevant, or NULL if neighborhood is always active */
782  )
783 {
785 
786  assert(scip != NULL);
787  assert(heurdata != NULL);
788  assert(neighborhood != NULL);
789  assert(name != NULL);
790 
791  SCIP_CALL( SCIPallocBlockMemory(scip, neighborhood) );
792  assert(*neighborhood != NULL);
793 
794  SCIP_ALLOC( BMSduplicateMemoryArray(&(*neighborhood)->name, name, strlen(name)+1) );
795 
796  SCIP_CALL( SCIPcreateClock(scip, &(*neighborhood)->stats.setupclock) );
797  SCIP_CALL( SCIPcreateClock(scip, &(*neighborhood)->stats.submipclock) );
798 
799  (*neighborhood)->changesubscip = changesubscip;
800  (*neighborhood)->varfixings = varfixings;
801  (*neighborhood)->nhinit = nhinit;
802  (*neighborhood)->nhexit = nhexit;
803  (*neighborhood)->nhfree = nhfree;
804  (*neighborhood)->nhrefsol = nhrefsol;
805  (*neighborhood)->nhdeactivate = nhdeactivate;
806 
807  /* add parameters for this neighborhood */
808  (void) SCIPsnprintf(paramname, SCIP_MAXSTRLEN, "heuristics/alns/%s/minfixingrate", name);
809  SCIP_CALL( SCIPaddRealParam(scip, paramname, "minimum fixing rate for this neighborhood",
810  &(*neighborhood)->fixingrate.minfixingrate, TRUE, minfixingrate, 0.0, 1.0, NULL, NULL) );
811  (void) SCIPsnprintf(paramname, SCIP_MAXSTRLEN, "heuristics/alns/%s/maxfixingrate", name);
812  SCIP_CALL( SCIPaddRealParam(scip, paramname, "maximum fixing rate for this neighborhood",
813  &(*neighborhood)->fixingrate.maxfixingrate, TRUE, maxfixingrate, 0.0, 1.0, NULL, NULL) );
814  (void) SCIPsnprintf(paramname, SCIP_MAXSTRLEN, "heuristics/alns/%s/active", name);
815  SCIP_CALL( SCIPaddBoolParam(scip, paramname, "is this neighborhood active?",
816  &(*neighborhood)->active, TRUE, active, NULL, NULL) );
817  (void) SCIPsnprintf(paramname, SCIP_MAXSTRLEN, "heuristics/alns/%s/priority", name);
818  SCIP_CALL( SCIPaddRealParam(scip, paramname, "positive call priority to initialize bandit algorithms",
819  &(*neighborhood)->priority, TRUE, priority, 1e-2, 1.0, NULL, NULL) );
820 
821  /* add the neighborhood to the ALNS heuristic */
822  heurdata->neighborhoods[heurdata->nneighborhoods++] = (*neighborhood);
823 
824  return SCIP_OKAY;
825 }
826 
827 /** release all data and free neighborhood */
828 static
830  SCIP* scip, /**< SCIP data structure */
831  NH** neighborhood /**< pointer to neighborhood that should be freed */
832  )
833 {
834  NH* nhptr;
835  assert(scip != NULL);
836  assert(neighborhood != NULL);
837 
838  nhptr = *neighborhood;
839  assert(nhptr != NULL);
840 
841  BMSfreeMemoryArray(&nhptr->name);
842 
843  /* release further, neighborhood specific data structures */
844  if( nhptr->nhfree != NULL )
845  {
846  SCIP_CALL( nhptr->nhfree(scip, nhptr) );
847  }
848 
849  SCIP_CALL( SCIPfreeClock(scip, &nhptr->stats.setupclock) );
850  SCIP_CALL( SCIPfreeClock(scip, &nhptr->stats.submipclock) );
851 
852  SCIPfreeBlockMemory(scip, neighborhood);
853  *neighborhood = NULL;
854 
855  return SCIP_OKAY;
856 }
857 
858 /** initialize neighborhood specific data */
859 static
861  SCIP* scip, /**< SCIP data structure */
862  NH* neighborhood /**< neighborhood to initialize */
863  )
864 {
865  assert(scip != NULL);
866  assert(neighborhood != NULL);
867 
868  /* call the init callback of the neighborhood */
869  if( neighborhood->nhinit != NULL )
870  {
871  SCIP_CALL( neighborhood->nhinit(scip, neighborhood) );
872  }
873 
874  return SCIP_OKAY;
875 }
876 
877 /** deinitialize neighborhood specific data */
878 static
880  SCIP* scip, /**< SCIP data structure */
881  NH* neighborhood /**< neighborhood to initialize */
882  )
883 {
884  assert(scip != NULL);
885  assert(neighborhood != NULL);
886 
887  if( neighborhood->nhexit != NULL )
888  {
889  SCIP_CALL( neighborhood->nhexit(scip, neighborhood) );
890  }
891 
892  return SCIP_OKAY;
893 }
894 
895 /** creates a new solution for the original problem by copying the solution of the subproblem */
896 static
898  SCIP* subscip, /**< SCIP data structure of the subproblem */
899  SCIP_EVENTDATA* eventdata /**< event handler data */
900  )
901 {
902  SCIP* sourcescip; /* original SCIP data structure */
903  SCIP_VAR** subvars; /* the variables of the subproblem */
904  SCIP_HEUR* heur; /* alns heuristic structure */
905  SCIP_SOL* subsol; /* solution of the subproblem */
906  SCIP_SOL* newsol; /* solution to be created for the original problem */
907  SCIP_Bool success;
908  NH_STATS* runstats;
909  SCIP_SOL* oldbestsol;
910 
911  assert(subscip != NULL);
912 
913  subsol = SCIPgetBestSol(subscip);
914  assert(subsol != NULL);
915 
916  sourcescip = eventdata->sourcescip;
917  subvars = eventdata->subvars;
918  heur = eventdata->heur;
919  runstats = eventdata->runstats;
920  assert(sourcescip != NULL);
921  assert(sourcescip != subscip);
922  assert(heur != NULL);
923  assert(subvars != NULL);
924  assert(runstats != NULL);
925 
926  SCIP_CALL( SCIPtranslateSubSol(sourcescip, subscip, subsol, heur, subvars, &newsol) );
927 
928  oldbestsol = SCIPgetBestSol(sourcescip);
929 
930  /* in the special, experimental all rewards mode, the solution is only checked for feasibility
931  * but not stored
932  */
933  if( eventdata->allrewardsmode )
934  {
935  SCIP_CALL( SCIPcheckSol(sourcescip, newsol, FALSE, FALSE, TRUE, TRUE, TRUE, &success) );
936 
937  if( success )
938  {
939  runstats->nsolsfound++;
940  if( SCIPgetSolTransObj(sourcescip, newsol) < SCIPgetCutoffbound(sourcescip) )
941  runstats->nbestsolsfound++;
942  }
943 
944  SCIP_CALL( SCIPfreeSol(sourcescip, &newsol) );
945  }
946  else
947  {
948  /* try to add new solution to scip and free it immediately */
949  SCIP_CALL( SCIPtrySolFree(sourcescip, &newsol, FALSE, FALSE, TRUE, TRUE, TRUE, &success) );
950 
951  if( success )
952  {
953  runstats->nsolsfound++;
954  if( SCIPgetBestSol(sourcescip) != oldbestsol )
955  runstats->nbestsolsfound++;
956  }
957  }
958 
959  /* update new upper bound for reward later */
960  runstats->newupperbound = SCIPgetUpperbound(sourcescip);
961 
962  return SCIP_OKAY;
963 }
964 
965 
966 /* ---------------- Callback methods of event handler ---------------- */
967 
968 /** execution callback of the event handler
969  *
970  * transfer new solutions or interrupt the solving process manually
971  */
972 static
973 SCIP_DECL_EVENTEXEC(eventExecAlns)
974 {
975  assert(eventhdlr != NULL);
976  assert(eventdata != NULL);
977  assert(strcmp(SCIPeventhdlrGetName(eventhdlr), EVENTHDLR_NAME) == 0);
978  assert(event != NULL);
979  assert(SCIPeventGetType(event) & SCIP_EVENTTYPE_ALNS);
980  assert(eventdata != NULL);
981 
982  /* treat the different atomic events */
983  switch( SCIPeventGetType(event) )
984  {
987  /* try to transfer the solution to the original SCIP */
988  SCIP_CALL( transferSolution(scip, eventdata) );
989  break;
991  /* interrupt solution process of sub-SCIP */
992  if( SCIPgetNLPs(scip) > eventdata->lplimfac * eventdata->nodelimit )
993  {
994  SCIPdebugMsg(scip, "interrupt after %" SCIP_LONGINT_FORMAT " LPs\n", SCIPgetNLPs(scip));
995  SCIP_CALL( SCIPinterruptSolve(scip) );
996  }
997  break;
998  default:
999  break;
1000  }
1001 
1002  return SCIP_OKAY;
1003 }
1004 
1005 /** initialize neighborhood statistics before the next run */
1006 static
1007 void initRunStats(
1008  SCIP* scip, /**< SCIP data structure */
1009  NH_STATS* stats /**< run statistics */
1010  )
1011 {
1012  stats->nbestsolsfound = 0;
1013  stats->nsolsfound = 0;
1014  stats->usednodes = 0L;
1015  stats->nfixings = 0;
1016  stats->oldupperbound = SCIPgetUpperbound(scip);
1017  stats->newupperbound = SCIPgetUpperbound(scip);
1018 }
1019 
1020 /** update run stats after the sub SCIP was solved */
1021 static
1022 void updateRunStats(
1023  NH_STATS* stats, /**< run statistics */
1024  SCIP* subscip /**< sub-SCIP instance, or NULL */
1025  )
1026 {
1027  /* treat an untransformed subscip as if none was created */
1028  if( subscip != NULL && ! SCIPisTransformed(subscip) )
1029  subscip = NULL;
1030 
1031  stats->usednodes = subscip != NULL ? SCIPgetNNodes(subscip) : 0L;
1032 }
1033 
1034 /** get the histogram index for this status */
1035 static
1036 int getHistIndex(
1037  SCIP_STATUS subscipstatus /**< sub-SCIP status */
1038  )
1039 {
1040  switch (subscipstatus)
1041  {
1042  case SCIP_STATUS_OPTIMAL:
1043  return (int)HIDX_OPT;
1045  return (int)HIDX_INFEAS;
1046  case SCIP_STATUS_NODELIMIT:
1047  return (int)HIDX_NODELIM;
1049  return (int)HIDX_STALLNODE;
1050  case SCIP_STATUS_SOLLIMIT:
1052  return (int)HIDX_SOLLIM;
1054  return (int)HIDX_USR;
1055  default:
1056  return (int)HIDX_OTHER;
1057  } /*lint !e788*/
1058 }
1059 
1060 /** print neighborhood statistics */
1061 static
1063  SCIP* scip, /**< SCIP data structure */
1064  SCIP_HEURDATA* heurdata, /**< heuristic data */
1065  FILE* file /**< file handle, or NULL for standard out */
1066  )
1067 {
1068  int i;
1069  int j;
1071 
1072  SCIPinfoMessage(scip, file, "Neighborhoods : %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %4s %4s %4s %4s %4s %4s %4s %4s\n",
1073  "Calls", "SetupTime", "SolveTime", "SolveNodes", "Sols", "Best", "Exp3", "EpsGreedy", "UCB", "TgtFixRate",
1074  "Opt", "Inf", "Node", "Stal", "Sol", "Usr", "Othr", "Actv");
1075 
1076  /* loop over neighborhoods and fill in statistics */
1077  for( i = 0; i < heurdata->nneighborhoods; ++i )
1078  {
1079  NH* neighborhood;
1080  SCIP_Real proba;
1081  SCIP_Real ucb;
1082  SCIP_Real epsgreedyweight;
1083 
1084  neighborhood = heurdata->neighborhoods[i];
1085  SCIPinfoMessage(scip, file, " %-17s:", neighborhood->name);
1086  SCIPinfoMessage(scip, file, " %10d", neighborhood->stats.nruns);
1087  SCIPinfoMessage(scip, file, " %10.2f", SCIPgetClockTime(scip, neighborhood->stats.setupclock) );
1088  SCIPinfoMessage(scip, file, " %10.2f", SCIPgetClockTime(scip, neighborhood->stats.submipclock) );
1089  SCIPinfoMessage(scip, file, " %10" SCIP_LONGINT_FORMAT, neighborhood->stats.usednodes );
1090  SCIPinfoMessage(scip, file, " %10" SCIP_LONGINT_FORMAT, neighborhood->stats.nsolsfound);
1091  SCIPinfoMessage(scip, file, " %10" SCIP_LONGINT_FORMAT, neighborhood->stats.nbestsolsfound);
1092 
1093  proba = 0.0;
1094  ucb = 1.0;
1095  epsgreedyweight = -1.0;
1096 
1097  if( heurdata->bandit != NULL && i < heurdata->nactiveneighborhoods )
1098  {
1099  switch (heurdata->banditalgo)
1100  {
1101  case 'u':
1102  ucb = SCIPgetConfidenceBoundUcb(heurdata->bandit, i);
1103  break;
1104  case 'g':
1105  epsgreedyweight = SCIPgetWeightsEpsgreedy(heurdata->bandit)[i];
1106  break;
1107  case 'e':
1108  proba = SCIPgetProbabilityExp3(heurdata->bandit, i);
1109  break;
1110  default:
1111  break;
1112  }
1113  }
1114 
1115  SCIPinfoMessage(scip, file, " %10.5f", proba);
1116  SCIPinfoMessage(scip, file, " %10.5f", epsgreedyweight);
1117  SCIPinfoMessage(scip, file, " %10.5f", ucb);
1118  SCIPinfoMessage(scip, file, " %10.3f", neighborhood->fixingrate.targetfixingrate);
1119 
1120  /* loop over status histogram */
1121  for( j = 0; j < NHISTENTRIES; ++j )
1122  SCIPinfoMessage(scip, file, " %4d", neighborhood->stats.statushist[statusses[j]]);
1123 
1124  SCIPinfoMessage(scip, file, " %4d", i < heurdata->nactiveneighborhoods ? 1 : 0);
1125  SCIPinfoMessage(scip, file, "\n");
1126  }
1127 }
1128 
1129 /** update the statistics of the neighborhood based on the sub-SCIP run */
1130 static
1132  NH_STATS* runstats, /**< run statistics */
1133  NH* neighborhood, /**< the selected neighborhood */
1134  SCIP_STATUS subscipstatus /**< status of the sub-SCIP solve */
1135  )
1136 { /*lint --e{715}*/
1137  NH_STATS* stats;
1138  stats = &neighborhood->stats;
1139 
1140  /* copy run statistics into neighborhood statistics */
1141  stats->nbestsolsfound += runstats->nbestsolsfound;
1142  stats->nsolsfound += runstats->nsolsfound;
1143  stats->usednodes += runstats->usednodes;
1144  stats->nruns += 1;
1145 
1146  if( runstats->nbestsolsfound > 0 )
1148  else if( runstats->nsolsfound > 0 )
1149  stats->nrunsbestsol++;
1150 
1151  /* update the counter for the subscip status */
1152  ++stats->statushist[getHistIndex(subscipstatus)];
1153 }
1154 
1155 /** sort callback for variable pointers using the ALNS variable prioritization
1156  *
1157  * the variable prioritization works hierarchically as follows. A variable
1158  * a has the higher priority over b iff
1159  *
1160  * - variable distances should be used and a has a smaller distance than b
1161  * - variable reduced costs should be used and a has a smaller score than b
1162  * - variable pseudo costs should be used and a has a smaller score than b
1163  * - based on previously assigned random scores
1164  *
1165  * @note: distances are context-based. For fixing more variables,
1166  * distances are initialized from the already fixed variables.
1167  * For unfixing variables, distances are initialized starting
1168  * from the unfixed variables
1169  */
1170 static
1171 SCIP_DECL_SORTINDCOMP(sortIndCompAlns)
1172 { /*lint --e{715}*/
1173  VARPRIO* varprio;
1174 
1175  varprio = (VARPRIO*)dataptr;
1176  assert(varprio != NULL);
1177  assert(varprio->randscores != NULL);
1178 
1179  if( ind1 == ind2 )
1180  return 0;
1181 
1182  /* priority is on distances, if enabled. The variable which is closer in a breadth-first search sense to
1183  * the already fixed variables has precedence */
1184  if( varprio->usedistances )
1185  {
1186  int dist1;
1187  int dist2;
1188 
1189  dist1 = varprio->distances[ind1];
1190  dist2 = varprio->distances[ind2];
1191 
1192  if( dist1 < 0 )
1193  dist1 = INT_MAX;
1194 
1195  if( dist2 < 0 )
1196  dist2 = INT_MAX;
1197 
1198  assert(varprio->distances != NULL);
1199  if( dist1 < dist2 )
1200  return -1;
1201  else if( dist1 > dist2 )
1202  return 1;
1203  }
1204 
1205  assert(! varprio->usedistances || varprio->distances[ind1] == varprio->distances[ind2]);
1206 
1207  /* if the indices tie considering distances or distances are disabled -> use reduced cost information instead */
1208  if( varprio->useredcost )
1209  {
1210  assert(varprio->redcostscores != NULL);
1211 
1212  if( varprio->redcostscores[ind1] < varprio->redcostscores[ind2] )
1213  return -1;
1214  else if( varprio->redcostscores[ind1] > varprio->redcostscores[ind2] )
1215  return 1;
1216  }
1217 
1218  /* use pseudo cost scores if reduced costs are disabled or a tie was found */
1219  if( varprio->usepscost )
1220  {
1221  assert(varprio->pscostscores != NULL);
1222 
1223  /* prefer the variable with smaller pseudocost score */
1224  if( varprio->pscostscores[ind1] < varprio->pscostscores[ind2] )
1225  return -1;
1226  else if( varprio->pscostscores[ind1] > varprio->pscostscores[ind2] )
1227  return 1;
1228  }
1229 
1230  if( varprio->randscores[ind1] < varprio->randscores[ind2] )
1231  return -1;
1232  else if( varprio->randscores[ind1] > varprio->randscores[ind2] )
1233  return 1;
1234 
1235  return ind1 - ind2;
1236 }
1237 
1238 /** Compute the reduced cost score for this variable in the reference solution */
1239 static
1241  SCIP* scip, /**< SCIP data structure */
1242  SCIP_VAR* var, /**< the variable for which the score should be computed */
1243  SCIP_Real refsolval, /**< solution value in reference solution */
1244  SCIP_Bool uselocalredcost /**< should local reduced costs be used for generic (un)fixing? */
1245  )
1246 {
1247  SCIP_Real bestbound;
1248  SCIP_Real redcost;
1249  SCIP_Real score;
1250  assert(scip != NULL);
1251  assert(var != NULL);
1252 
1253  /* prefer column variables */
1255  return SCIPinfinity(scip);
1256 
1257  if( ! uselocalredcost )
1258  {
1259  redcost = SCIPvarGetBestRootRedcost(var);
1260 
1261  bestbound = SCIPvarGetBestRootSol(var);
1262 
1263  /* using global reduced costs, the two factors yield a nonnegative score within tolerances */
1264  assert(SCIPisDualfeasZero(scip, redcost)
1265  || (SCIPisDualfeasNegative(scip, redcost) && ! SCIPisFeasPositive(scip, refsolval - bestbound))
1266  || (SCIPisDualfeasPositive(scip, redcost) && ! SCIPisFeasNegative(scip, refsolval - bestbound)));
1267  }
1268  else
1269  {
1270  /* this can be safely asserted here, since the heuristic would not reach this point, otherwise */
1271  assert(SCIPhasCurrentNodeLP(scip));
1272  assert(SCIPgetLPSolstat(scip) == SCIP_LPSOLSTAT_OPTIMAL);
1273 
1274  redcost = SCIPgetVarRedcost(scip, var);
1275 
1276  bestbound = SCIPvarGetLPSol(var);
1277  }
1278 
1279  assert(! SCIPisInfinity(scip, REALABS(bestbound)));
1280  assert(SCIPisDualfeasZero(scip, redcost) || SCIPisFeasIntegral(scip, bestbound));
1281 
1282  score = redcost * (refsolval - bestbound);
1283 
1284  /* max out numerical inaccuracies from global scores */
1285  if( ! uselocalredcost )
1286  score = MAX(score, 0.0);
1287 
1288  return score;
1289 }
1290 
1291 /** get the pseudo cost score of this variable with respect to the reference solution */
1292 static
1294  SCIP* scip, /**< SCIP data structure */
1295  SCIP_VAR* var, /**< the variable for which the score should be computed */
1296  SCIP_Real refsolval /**< solution value in reference solution */
1297  )
1298 {
1299  SCIP_Real rootsolval;
1300 
1301  assert(scip != NULL);
1302  assert(var != NULL);
1303 
1304  /* variables that aren't LP columns have no pseudocost score */
1306  return 0.0;
1307 
1308  rootsolval = SCIPvarGetRootSol(var);
1309 
1310  /* the score is 0.0 if the values are equal */
1311  if( SCIPisEQ(scip, rootsolval, refsolval) )
1312  return 0.0;
1313  else
1314  return SCIPgetVarPseudocostVal(scip, var, refsolval - rootsolval);
1315 }
1316 
1317 /** add variable and solution value to buffer data structure for variable fixings. The method checks if
1318  * the value still lies within the variable bounds. The value stays unfixed otherwise.
1319  */
1320 static
1322  SCIP* scip, /**< SCIP data structure */
1323  SCIP_VAR* var, /**< (source) SCIP variable that should be added to the buffer */
1324  SCIP_Real val, /**< fixing value for this variable */
1325  SCIP_VAR** varbuf, /**< variable buffer to store variables that should be fixed */
1326  SCIP_Real* valbuf, /**< value buffer to store fixing values */
1327  int* nfixings, /**< pointer to number of fixed buffer variables, will be increased by 1 */
1328  SCIP_Bool integer /**< is this an integer variable? */
1329  )
1330 {
1331  assert(SCIPisFeasIntegral(scip, val) || ! SCIPvarIsIntegral(var));
1332  assert(*nfixings < SCIPgetNVars(scip));
1333 
1334  /* round the value to its nearest integer */
1335  if( integer )
1336  val = SCIPfloor(scip, val + 0.5);
1337 
1338  /* only add fixing if it is still valid within the global variable bounds. Invalidity
1339  * of this solution value may come from a dual reduction that was performed after the solution from which
1340  * this value originated was found
1341  */
1342  if( SCIPvarGetLbGlobal(var) <= val && val <= SCIPvarGetUbGlobal(var) )
1343  {
1344  varbuf[*nfixings] = var;
1345  valbuf[*nfixings] = val;
1346  ++(*nfixings);
1347  }
1348 }
1349 
1350 /** query neighborhood for a reference solution for further fixings */
1351 static
1353  SCIP* scip, /**< SCIP data structure */
1354  NH* neighborhood, /**< ALNS neighborhood data structure */
1355  SCIP_SOL** solptr /**< solution pointer */
1356  )
1357 {
1358  assert(solptr != NULL);
1359  assert(scip != NULL);
1360  assert(neighborhood != NULL);
1361 
1362  *solptr = NULL;
1363  if( neighborhood->nhrefsol != NULL )
1364  {
1365  SCIP_RESULT result;
1366  SCIP_CALL( neighborhood->nhrefsol(scip, neighborhood, solptr, &result) );
1367 
1368  if( result == SCIP_DIDNOTFIND )
1369  *solptr = NULL;
1370  else
1371  assert(*solptr != NULL);
1372  }
1373 
1374  return SCIP_OKAY;
1375 }
1376 
1377 /** fix additional variables found in feasible reference solution if the ones that the neighborhood found were not enough
1378  *
1379  * use not always the best solution for the values, but a reference solution provided by the neighborhood itself
1380  *
1381  * @note it may happen that the target fixing rate is not completely reached. This is the case if intermediate,
1382  * dual reductions render the solution values of the reference solution infeasible for
1383  * the current, global variable bounds.
1384  */
1385 static
1387  SCIP* scip, /**< SCIP data structure */
1388  SCIP_HEURDATA* heurdata, /**< heuristic data of the ALNS neighborhood */
1389  SCIP_SOL* refsol, /**< feasible reference solution for more variable fixings */
1390  SCIP_VAR** varbuf, /**< buffer array to store variables to fix */
1391  SCIP_Real* valbuf, /**< buffer array to store fixing values */
1392  int* nfixings, /**< pointer to store the number of fixings */
1393  int ntargetfixings, /**< number of required target fixings */
1394  SCIP_Bool* success /**< pointer to store whether the target fixings have been successfully reached */
1395  )
1396 {
1397  VARPRIO varprio;
1398  SCIP_VAR** vars;
1399  SCIP_Real* redcostscores;
1400  SCIP_Real* pscostscores;
1401  SCIP_Real* solvals;
1402  SCIP_RANDNUMGEN* rng;
1403  SCIP_VAR** unfixedvars;
1404  SCIP_Bool* isfixed;
1405  int* distances;
1406  int* perm;
1407  SCIP_Real* randscores;
1408  int nbinvars;
1409  int nintvars;
1410  int nbinintvars;
1411  int nvars;
1412  int b;
1413  int nvarstoadd;
1414  int nunfixedvars;
1415 
1416  assert(scip != NULL);
1417  assert(varbuf != NULL);
1418  assert(nfixings != NULL);
1419  assert(success != NULL);
1420  assert(heurdata != NULL);
1421  assert(refsol != NULL);
1422 
1423  *success = FALSE;
1424 
1425  /* if the user parameter forbids more fixings, return immediately */
1426  if( ! heurdata->domorefixings )
1427  return SCIP_OKAY;
1428 
1429  SCIP_CALL( SCIPgetVarsData(scip, &vars, &nvars, &nbinvars, &nintvars, NULL, NULL) );
1430 
1431  nbinintvars = nbinvars + nintvars;
1432 
1433  if( ntargetfixings >= nbinintvars )
1434  return SCIP_OKAY;
1435 
1436  /* determine the number of required additional fixings */
1437  nvarstoadd = ntargetfixings - *nfixings;
1438  if( nvarstoadd == 0 )
1439  return SCIP_OKAY;
1440 
1441  varprio.usedistances = heurdata->usedistances && (*nfixings >= 1);
1442  varprio.useredcost = heurdata->useredcost;
1443  varprio.usepscost = heurdata->usepscost;
1444  varprio.scip = scip;
1445  rng = SCIPbanditGetRandnumgen(heurdata->bandit);
1446  assert(rng != NULL);
1447 
1448  SCIP_CALL( SCIPallocBufferArray(scip, &randscores, nbinintvars) );
1449  SCIP_CALL( SCIPallocBufferArray(scip, &perm, nbinintvars) );
1450  SCIP_CALL( SCIPallocBufferArray(scip, &distances, nvars) );
1451  SCIP_CALL( SCIPallocBufferArray(scip, &redcostscores, nbinintvars) );
1452  SCIP_CALL( SCIPallocBufferArray(scip, &solvals, nbinintvars) );
1453  SCIP_CALL( SCIPallocBufferArray(scip, &isfixed, nbinintvars) );
1454  SCIP_CALL( SCIPallocBufferArray(scip, &unfixedvars, nbinintvars) );
1455  SCIP_CALL( SCIPallocBufferArray(scip, &pscostscores, nbinintvars) );
1456 
1457  /* initialize variable graph distances from already fixed variables */
1458  if( varprio.usedistances )
1459  {
1460  SCIP_CALL( SCIPvariablegraphBreadthFirst(scip, NULL, varbuf, *nfixings, distances, INT_MAX, INT_MAX, ntargetfixings) );
1461  }
1462  else
1463  {
1464  /* initialize all equal distances to make them irrelevant */
1465  BMSclearMemoryArray(distances, nbinintvars);
1466  }
1467 
1468  BMSclearMemoryArray(isfixed, nbinintvars);
1469 
1470  /* mark binary and integer variables if they are fixed */
1471  for( b = 0; b < *nfixings; ++b )
1472  {
1473  int probindex;
1474 
1475  assert(varbuf[b] != NULL);
1476  probindex = SCIPvarGetProbindex(varbuf[b]);
1477  assert(probindex >= 0);
1478 
1479  if( probindex < nbinintvars )
1480  isfixed[probindex] = TRUE;
1481  }
1482 
1483  SCIP_CALL( SCIPgetSolVals(scip, refsol, nbinintvars, vars, solvals) );
1484 
1485  /* assign scores to unfixed every discrete variable of the problem */
1486  nunfixedvars = 0;
1487  for( b = 0; b < nbinintvars; ++b )
1488  {
1489  SCIP_VAR* var = vars[b];
1490 
1491  /* filter fixed variables */
1492  if( isfixed[b] )
1493  continue;
1494 
1495  /* filter variables with a solution value outside its global bounds */
1496  if( solvals[b] < SCIPvarGetLbGlobal(var) - 0.5 || solvals[b] > SCIPvarGetUbGlobal(var) + 0.5 )
1497  continue;
1498 
1499  redcostscores[nunfixedvars] = getVariableRedcostScore(scip, var, solvals[b], heurdata->uselocalredcost);
1500  pscostscores[nunfixedvars] = getVariablePscostScore(scip, var, solvals[b]);
1501 
1502  unfixedvars[nunfixedvars] = var;
1503  perm[nunfixedvars] = nunfixedvars;
1504  randscores[nunfixedvars] = SCIPrandomGetReal(rng, 0.0, 1.0);
1505 
1506  /* these assignments are based on the fact that nunfixedvars <= b */
1507  solvals[nunfixedvars] = solvals[b];
1508  distances[nunfixedvars] = distances[b];
1509 
1510  SCIPdebugMsg(scip, "Var <%s> scores: dist %3d, red cost %15.9g, pscost %15.9g rand %6.4f\n",
1511  SCIPvarGetName(var), distances[nunfixedvars], redcostscores[nunfixedvars],
1512  pscostscores[nunfixedvars], randscores[nunfixedvars]);
1513 
1514  nunfixedvars++;
1515  }
1516 
1517  /* use selection algorithm (order of the variables does not matter) for quickly completing the fixing */
1518  varprio.randscores = randscores;
1519  varprio.distances = distances;
1520  varprio.redcostscores = redcostscores;
1521  varprio.pscostscores = pscostscores;
1522 
1523  nvarstoadd = MIN(nunfixedvars, nvarstoadd);
1524 
1525  /* select the first nvarstoadd many variables according to the score */
1526  if( nvarstoadd < nunfixedvars )
1527  SCIPselectInd(perm, sortIndCompAlns, &varprio, nvarstoadd, nunfixedvars);
1528 
1529  /* loop over the first elements of the selection defined in permutation. They represent the best variables */
1530  for( b = 0; b < nvarstoadd; ++b )
1531  {
1532  int permindex = perm[b];
1533  assert(permindex >= 0);
1534  assert(permindex < nunfixedvars);
1535 
1536  tryAdd2variableBuffer(scip, unfixedvars[permindex], solvals[permindex], varbuf, valbuf, nfixings, TRUE);
1537  }
1538 
1539  *success = TRUE;
1540 
1541  /* free buffer arrays */
1542  SCIPfreeBufferArray(scip, &pscostscores);
1543  SCIPfreeBufferArray(scip, &unfixedvars);
1544  SCIPfreeBufferArray(scip, &isfixed);
1545  SCIPfreeBufferArray(scip, &solvals);
1546  SCIPfreeBufferArray(scip, &redcostscores);
1547  SCIPfreeBufferArray(scip, &distances);
1548  SCIPfreeBufferArray(scip, &perm);
1549  SCIPfreeBufferArray(scip, &randscores);
1550 
1551  return SCIP_OKAY;
1552 }
1553 
1554 /** create the bandit algorithm for the heuristic depending on the user parameter */
1555 static
1557  SCIP* scip, /**< SCIP data structure */
1558  SCIP_HEURDATA* heurdata, /**< heuristic data structure */
1559  SCIP_Real* priorities, /**< call priorities for active neighborhoods */
1560  unsigned int initseed /**< initial random seed */
1561  )
1562 {
1563  switch (heurdata->banditalgo)
1564  {
1565  case 'u':
1566  SCIP_CALL( SCIPcreateBanditUcb(scip, &heurdata->bandit, priorities,
1567  heurdata->ucb_alpha, heurdata->nactiveneighborhoods, initseed) );
1568  break;
1569 
1570  case 'e':
1571  SCIP_CALL( SCIPcreateBanditExp3(scip, &heurdata->bandit, priorities,
1572  heurdata->exp3_gamma, heurdata->exp3_beta, heurdata->nactiveneighborhoods, initseed) );
1573  break;
1574 
1575  case 'g':
1576  SCIP_CALL( SCIPcreateBanditEpsgreedy(scip, &heurdata->bandit, priorities,
1577  heurdata->epsgreedy_eps, FALSE, 0.9, 0, heurdata->nactiveneighborhoods, initseed) );
1578  break;
1579 
1580  default:
1581  SCIPerrorMessage("Unknown bandit parameter %c\n", heurdata->banditalgo);
1582  return SCIP_INVALIDDATA;
1583  }
1584 
1585  return SCIP_OKAY;
1586 }
1587 
1588 /*
1589  * Callback methods of primal heuristic
1590  */
1591 
1592 /** copy method for primal heuristic plugins (called when SCIP copies plugins) */
1593 static
1594 SCIP_DECL_HEURCOPY(heurCopyAlns)
1595 { /*lint --e{715}*/
1596  assert(scip != NULL);
1597  assert(heur != NULL);
1598  assert(strcmp(SCIPheurGetName(heur), HEUR_NAME) == 0);
1599 
1600  /* call inclusion method of primal heuristic */
1601  SCIP_CALL( SCIPincludeHeurAlns(scip) );
1602 
1603  return SCIP_OKAY;
1604 }
1605 
1606 /** unfix some of the variables because there are too many fixed
1607  *
1608  * a variable is ideally unfixed if it is close to other unfixed variables
1609  * and fixing it has a high reduced cost impact
1610  */
1611 static
1613  SCIP* scip, /**< SCIP data structure */
1614  SCIP_HEURDATA* heurdata, /**< heuristic data of the ALNS neighborhood */
1615  SCIP_VAR** varbuf, /**< buffer array to store variables to fix */
1616  SCIP_Real* valbuf, /**< buffer array to store fixing values */
1617  int* nfixings, /**< pointer to store the number of fixings */
1618  int ntargetfixings, /**< number of required target fixings */
1619  SCIP_Bool* success /**< pointer to store whether the target fixings have been successfully reached */
1620  )
1621 {
1622  VARPRIO varprio;
1623  SCIP_Real* redcostscores;
1624  SCIP_Real* pscostscores;
1625  SCIP_Real* randscores;
1626  SCIP_VAR** unfixedvars;
1627  SCIP_VAR** varbufcpy;
1628  SCIP_Real* valbufcpy;
1629  SCIP_Bool* isfixedvar;
1630  SCIP_VAR** vars;
1631  SCIP_RANDNUMGEN* rng;
1632  int* distances;
1633  int* fixeddistances;
1634  int* perm;
1635  int nvars;
1636  int i;
1637  int nbinintvars;
1638  int nunfixed;
1639 
1640  *success = FALSE;
1641 
1642  nbinintvars = SCIPgetNBinVars(scip) + SCIPgetNIntVars(scip);
1643  if( nbinintvars == 0 )
1644  return SCIP_OKAY;
1645 
1646  assert(*nfixings > 0);
1647 
1648  nvars = SCIPgetNVars(scip);
1649  SCIP_CALL( SCIPallocBufferArray(scip, &isfixedvar, nvars) );
1650  SCIP_CALL( SCIPallocBufferArray(scip, &unfixedvars, nbinintvars) );
1651  SCIP_CALL( SCIPallocBufferArray(scip, &distances, nvars) );
1652  SCIP_CALL( SCIPallocBufferArray(scip, &fixeddistances, *nfixings) );
1653  SCIP_CALL( SCIPallocBufferArray(scip, &redcostscores, *nfixings) );
1654  SCIP_CALL( SCIPallocBufferArray(scip, &randscores, *nfixings) );
1655  SCIP_CALL( SCIPallocBufferArray(scip, &perm, *nfixings) );
1656  SCIP_CALL( SCIPallocBufferArray(scip, &pscostscores, *nfixings) );
1657 
1658  SCIP_CALL( SCIPduplicateBufferArray(scip, &varbufcpy, varbuf, *nfixings) );
1659  SCIP_CALL( SCIPduplicateBufferArray(scip, &valbufcpy, valbuf, *nfixings) );
1660 
1661  /*
1662  * collect the unfixed binary and integer variables
1663  */
1664  BMSclearMemoryArray(isfixedvar, nvars);
1665  /* loop over fixed variables and mark their respective positions as fixed */
1666  for( i = 0; i < *nfixings; ++i )
1667  {
1668  int probindex = SCIPvarGetProbindex(varbuf[i]);
1669 
1670  assert(probindex >= 0);
1671 
1672  isfixedvar[probindex] = TRUE;
1673  }
1674 
1675  nunfixed = 0;
1676  vars = SCIPgetVars(scip);
1677  /* collect unfixed binary and integer variables */
1678  for( i = 0; i < nbinintvars; ++i )
1679  {
1680  if( ! isfixedvar[i] )
1681  unfixedvars[nunfixed++] = vars[i];
1682  }
1683 
1684  varprio.usedistances = heurdata->usedistances && nunfixed > 0;
1685 
1686  /* collect distances of all fixed variables from those that are not fixed */
1687  if( varprio.usedistances )
1688  {
1689  SCIP_CALL( SCIPvariablegraphBreadthFirst(scip, NULL, unfixedvars, nunfixed, distances, INT_MAX, INT_MAX, INT_MAX) );
1690 
1691  for( i = 0; i < *nfixings; ++i )
1692  {
1693  int probindex = SCIPvarGetProbindex(varbuf[i]);
1694  if( probindex >= 0 )
1695  fixeddistances[i] = distances[probindex];
1696  }
1697  }
1698  else
1699  {
1700  BMSclearMemoryArray(fixeddistances, *nfixings);
1701  }
1702 
1703  /* collect reduced cost scores of the fixings and assign random scores */
1704  rng = SCIPbanditGetRandnumgen(heurdata->bandit);
1705  for( i = 0; i < *nfixings; ++i )
1706  {
1707  SCIP_VAR* fixedvar = varbuf[i];
1708  SCIP_Real fixval = valbuf[i];
1709 
1710  /* use negative reduced cost and pseudo cost scores to prefer variable fixings with small score */
1711  redcostscores[i] = - getVariableRedcostScore(scip, fixedvar, fixval, heurdata->uselocalredcost);
1712  pscostscores[i] = - getVariablePscostScore(scip, fixedvar, fixval);
1713  randscores[i] = SCIPrandomGetReal(rng, 0.0, 1.0);
1714  perm[i] = i;
1715 
1716  SCIPdebugMsg(scip, "Var <%s> scores: dist %3d, red cost %15.9g, pscost %15.9g rand %6.4f\n",
1717  SCIPvarGetName(fixedvar), fixeddistances[i], redcostscores[i], pscostscores[i], randscores[i]);
1718  }
1719 
1720  varprio.distances = fixeddistances;
1721  varprio.randscores = randscores;
1722  varprio.redcostscores = redcostscores;
1723  varprio.pscostscores = pscostscores;
1724  varprio.useredcost = heurdata->useredcost;
1725  varprio.usepscost = heurdata->usepscost;
1726  varprio.scip = scip;
1727 
1728  /* scores are assigned in such a way that variables with a smaller score should be fixed last */
1729  SCIPselectDownInd(perm, sortIndCompAlns, &varprio, ntargetfixings, *nfixings);
1730 
1731  /* bring the desired variables to the front of the array */
1732  for( i = 0; i < ntargetfixings; ++i )
1733  {
1734  valbuf[i] = valbufcpy[perm[i]];
1735  varbuf[i] = varbufcpy[perm[i]];
1736  }
1737 
1738  *nfixings = ntargetfixings;
1739 
1740  /* free the buffer arrays in reverse order of allocation */
1741  SCIPfreeBufferArray(scip, &valbufcpy);
1742  SCIPfreeBufferArray(scip, &varbufcpy);
1743  SCIPfreeBufferArray(scip, &pscostscores);
1744  SCIPfreeBufferArray(scip, &perm);
1745  SCIPfreeBufferArray(scip, &randscores);
1746  SCIPfreeBufferArray(scip, &redcostscores);
1747  SCIPfreeBufferArray(scip, &fixeddistances);
1748  SCIPfreeBufferArray(scip, &distances);
1749  SCIPfreeBufferArray(scip, &unfixedvars);
1750  SCIPfreeBufferArray(scip, &isfixedvar);
1751 
1752  *success = TRUE;
1753 
1754  return SCIP_OKAY;
1755 }
1756 
1757 /** call variable fixing callback for this neighborhood and orchestrate additional variable fixings, if necessary */
1758 static
1760  SCIP* scip, /**< SCIP data structure */
1761  SCIP_HEURDATA* heurdata, /**< heuristic data of the ALNS neighborhood */
1762  NH* neighborhood, /**< neighborhood data structure */
1763  SCIP_VAR** varbuf, /**< buffer array to keep variables that should be fixed */
1764  SCIP_Real* valbuf, /**< buffer array to keep fixing values */
1765  int* nfixings, /**< pointer to store the number of variable fixings */
1766  SCIP_RESULT* result /**< pointer to store the result of the fixing operation */
1767  )
1768 {
1769  int ntargetfixings;
1770  int nmaxfixings;
1771  int nminfixings;
1772  int nbinintvars;
1773 
1774  assert(scip != NULL);
1775  assert(neighborhood != NULL);
1776  assert(varbuf != NULL);
1777  assert(valbuf != NULL);
1778  assert(nfixings != NULL);
1779  assert(result != NULL);
1780 
1781  *nfixings = 0;
1782 
1783  *result = SCIP_DIDNOTRUN;
1784  ntargetfixings = (int)(neighborhood->fixingrate.targetfixingrate * (SCIPgetNBinVars(scip) + SCIPgetNIntVars(scip)));
1785 
1786  if( neighborhood->varfixings != NULL )
1787  {
1788  SCIP_CALL( neighborhood->varfixings(scip, neighborhood, varbuf, valbuf, nfixings, result) );
1789 
1790  if( *result != SCIP_SUCCESS )
1791  return SCIP_OKAY;
1792  }
1793  else if( ntargetfixings == 0 )
1794  {
1795  *result = SCIP_SUCCESS;
1796 
1797  return SCIP_OKAY;
1798  }
1799 
1800  /* compute upper and lower target fixing limits using tolerance parameters */
1801  assert(neighborhood->varfixings == NULL || *result != SCIP_DIDNOTRUN);
1802  nbinintvars = SCIPgetNBinVars(scip) + SCIPgetNIntVars(scip);
1803  ntargetfixings = (int)(neighborhood->fixingrate.targetfixingrate * nbinintvars);
1804  nminfixings = (int)((neighborhood->fixingrate.targetfixingrate - heurdata->fixtol) * nbinintvars);
1805  nminfixings = MAX(nminfixings, 0);
1806  nmaxfixings = (int)((neighborhood->fixingrate.targetfixingrate + heurdata->unfixtol) * nbinintvars);
1807  nmaxfixings = MIN(nmaxfixings, nbinintvars);
1808 
1809  SCIPdebugMsg(scip, "Neighborhood Fixings/Target: %d / %d <= %d <= %d\n",*nfixings, nminfixings, ntargetfixings, nmaxfixings);
1810 
1811  /* if too few fixings, use a strategy to select more variable fixings: randomized, LP graph, ReducedCost based, mix */
1812  if( (*result == SCIP_SUCCESS || *result == SCIP_DIDNOTRUN) && (*nfixings < nminfixings) )
1813  {
1814  SCIP_Bool success;
1815  SCIP_SOL* refsol;
1816 
1817  /* get reference solution from neighborhood */
1818  SCIP_CALL( neighborhoodGetRefsol(scip, neighborhood, &refsol) );
1819 
1820  /* try to fix more variables based on the reference solution */
1821  if( refsol != NULL )
1822  {
1823  SCIP_CALL( alnsFixMoreVariables(scip, heurdata, refsol, varbuf, valbuf, nfixings, ntargetfixings, &success) );
1824  }
1825  else
1826  success = FALSE;
1827 
1828  if( success )
1829  *result = SCIP_SUCCESS;
1830  else if( *result == SCIP_SUCCESS )
1831  *result = SCIP_DIDNOTFIND;
1832  else
1833  *result = SCIP_DIDNOTRUN;
1834 
1835  SCIPdebugMsg(scip, "After additional fixings: %d / %d\n",*nfixings, ntargetfixings);
1836  }
1837  else if( (SCIP_Real)(*nfixings) > nmaxfixings )
1838  {
1839  SCIP_Bool success;
1840 
1841  SCIP_CALL( alnsUnfixVariables(scip, heurdata, varbuf, valbuf, nfixings, ntargetfixings, &success) );
1842 
1843  assert(success);
1844  *result = SCIP_SUCCESS;
1845  SCIPdebugMsg(scip, "Unfixed variables, fixed variables remaining: %d\n", ntargetfixings);
1846  }
1847  else
1848  {
1849  SCIPdebugMsg(scip, "No additional fixings performed\n");
1850  }
1851 
1852  return SCIP_OKAY;
1853 }
1854 
1855 /** change the sub-SCIP by restricting variable domains, changing objective coefficients, or adding constraints */
1856 static
1858  SCIP* sourcescip, /**< source SCIP data structure */
1859  SCIP* targetscip, /**< target SCIP data structure */
1860  NH* neighborhood, /**< neighborhood */
1861  SCIP_VAR** targetvars, /**< array of target SCIP variables aligned with source SCIP variables */
1862  int* ndomchgs, /**< pointer to store the number of variable domain changes */
1863  int* nchgobjs, /**< pointer to store the number of changed objective coefficients */
1864  int* naddedconss, /**< pointer to store the number of added constraints */
1865  SCIP_Bool* success /**< pointer to store whether the sub-SCIP has been successfully modified */
1866  )
1867 {
1868  assert(sourcescip != NULL);
1869  assert(targetscip != NULL);
1870  assert(neighborhood != NULL);
1871  assert(targetvars != NULL);
1872  assert(ndomchgs != NULL);
1873  assert(nchgobjs != NULL);
1874  assert(naddedconss != NULL);
1875  assert(success != NULL);
1876 
1877  *success = FALSE;
1878  *ndomchgs = 0;
1879  *nchgobjs = 0;
1880  *naddedconss = 0;
1881 
1882  /* call the change sub-SCIP callback of the neighborhood */
1883  if( neighborhood->changesubscip != NULL )
1884  {
1885  SCIP_CALL( neighborhood->changesubscip(sourcescip, targetscip, neighborhood, targetvars, ndomchgs, nchgobjs, naddedconss, success) );
1886  }
1887  else
1888  {
1889  *success = TRUE;
1890  }
1891 
1892  return SCIP_OKAY;
1893 }
1894 
1895 /** set sub-SCIP solving limits */
1896 static
1898  SCIP* subscip, /**< SCIP data structure */
1899  SOLVELIMITS* solvelimits /**< pointer to solving limits data structure */
1900  )
1901 {
1902  assert(subscip != NULL);
1903  assert(solvelimits != NULL);
1904 
1905  assert(solvelimits->nodelimit >= solvelimits->stallnodes);
1906 
1907  SCIP_CALL( SCIPsetLongintParam(subscip, "limits/nodes", solvelimits->nodelimit) );
1908  SCIP_CALL( SCIPsetLongintParam(subscip, "limits/stallnodes", solvelimits->stallnodes));
1909  SCIP_CALL( SCIPsetRealParam(subscip, "limits/time", solvelimits->timelimit) );
1910  SCIP_CALL( SCIPsetRealParam(subscip, "limits/memory", solvelimits->memorylimit) );
1911 
1912  return SCIP_OKAY;
1913 }
1914 
1915 /** determine limits for a sub-SCIP */
1916 static
1918  SCIP* scip, /**< SCIP data structure */
1919  SCIP_HEUR* heur, /**< this heuristic */
1920  SOLVELIMITS* solvelimits, /**< pointer to solving limits data structure */
1921  SCIP_Bool* runagain /**< can we solve another sub-SCIP with these limits */
1922  )
1923 {
1924  SCIP_HEURDATA* heurdata;
1925  SCIP_Real initfactor;
1926  SCIP_Real nodesquot;
1927 
1928  assert(scip != NULL);
1929  assert(heur != NULL);
1930  assert(solvelimits != NULL);
1931  assert(runagain != NULL);
1932 
1933  heurdata = SCIPheurGetData(heur);
1934 
1935  /* check whether there is enough time and memory left */
1936  SCIP_CALL( SCIPgetRealParam(scip, "limits/time", &solvelimits->timelimit) );
1937  if( ! SCIPisInfinity(scip, solvelimits->timelimit) )
1938  solvelimits->timelimit -= SCIPgetSolvingTime(scip);
1939  SCIP_CALL( SCIPgetRealParam(scip, "limits/memory", &solvelimits->memorylimit) );
1940 
1941  /* substract the memory already used by the main SCIP and the estimated memory usage of external software */
1942  if( ! SCIPisInfinity(scip, solvelimits->memorylimit) )
1943  {
1944  solvelimits->memorylimit -= SCIPgetMemUsed(scip)/1048576.0;
1945  solvelimits->memorylimit -= SCIPgetMemExternEstim(scip)/1048576.0;
1946  }
1947 
1948  /* abort if no time is left or not enough memory to create a copy of SCIP, including external memory usage */
1949  if( solvelimits->timelimit <= 0.0 || solvelimits->memorylimit <= 2.0*SCIPgetMemExternEstim(scip)/1048576.0 )
1950  *runagain = FALSE;
1951 
1952  nodesquot = heurdata->nodesquot;
1953 
1954  /* if the heuristic is used to measure all rewards, it will always be penalized here */
1955  if( heurdata->rewardfile == NULL )
1956  nodesquot *= (SCIPheurGetNBestSolsFound(heur) + 1.0)/(SCIPheurGetNCalls(heur) + 1.0);
1957 
1958  /* calculate the search node limit of the heuristic */
1959  solvelimits->stallnodes = (SCIP_Longint)(nodesquot * SCIPgetNNodes(scip));
1960  solvelimits->stallnodes += heurdata->nodesoffset;
1961  solvelimits->stallnodes -= heurdata->usednodes;
1962  solvelimits->stallnodes -= 100 * SCIPheurGetNCalls(heur);
1963  solvelimits->stallnodes = MIN(heurdata->maxnodes, solvelimits->stallnodes);
1964 
1965  /* use a smaller budget if not all neighborhoods have been initialized yet */
1966  assert(heurdata->ninitneighborhoods >= 0);
1967  initfactor = (heurdata->nactiveneighborhoods - heurdata->ninitneighborhoods + 1.0) / (heurdata->nactiveneighborhoods + 1.0);
1968  solvelimits->stallnodes = (SCIP_Longint)(solvelimits->stallnodes * initfactor);
1969  solvelimits->nodelimit = (SCIP_Longint)(heurdata->maxnodes);
1970 
1971  /* check whether we have enough nodes left to call subproblem solving */
1972  if( solvelimits->stallnodes < heurdata->targetnodes )
1973  *runagain = FALSE;
1974 
1975  return SCIP_OKAY;
1976 }
1977 
1978 /** return the bandit algorithm that should be used */
1979 static
1981  SCIP_HEURDATA* heurdata /**< heuristic data of the ALNS neighborhood */
1982  )
1983 {
1984  assert(heurdata != NULL);
1985  return heurdata->bandit;
1986 }
1987 
1988 /** select a neighborhood depending on the selected bandit algorithm */
1989 static
1991  SCIP* scip, /**< SCIP data structure */
1992  SCIP_HEURDATA* heurdata, /**< heuristic data of the ALNS neighborhood */
1993  int* neighborhoodidx /**< pointer to store the selected neighborhood index */
1994  )
1995 {
1996  SCIP_BANDIT* bandit;
1997  assert(scip != NULL);
1998  assert(heurdata != NULL);
1999  assert(neighborhoodidx != NULL);
2000 
2001  *neighborhoodidx = -1;
2002 
2003  bandit = getBandit(heurdata);
2004 
2005  SCIP_CALL( SCIPbanditSelect(bandit, neighborhoodidx) );
2006  assert(*neighborhoodidx >= 0);
2007 
2008  return SCIP_OKAY;
2009 }
2010 
2011 /** Calculate reward based on the selected reward measure */
2012 static
2014  SCIP* scip, /**< SCIP data structure */
2015  SCIP_HEURDATA* heurdata, /**< heuristic data of the ALNS neighborhood */
2016  NH_STATS* runstats, /**< run statistics */
2017  SCIP_Real* rewardptr /**< pointer to store the computed reward */
2018  )
2019 {
2020  SCIP_Real reward = 0.0;
2021  SCIP_Real effort;
2022  int ndiscretevars;
2023 
2024  assert(rewardptr != NULL);
2025  assert(runstats->usednodes >= 0);
2026  assert(runstats->nfixings >= 0);
2027 
2028  effort = runstats->usednodes / 100.0;
2029 
2030  ndiscretevars = SCIPgetNBinVars(scip) + SCIPgetNIntVars(scip);
2031  /* assume that every fixed variable linearly reduces the subproblem complexity */
2032  if( ndiscretevars > 0 )
2033  {
2034  effort = (1.0 - (runstats->nfixings / (SCIP_Real)ndiscretevars)) * effort;
2035  }
2036  assert(rewardptr != NULL);
2037 
2038  /* a positive reward is only assigned if a new incumbent solution was found */
2039  if( runstats->nbestsolsfound > 0 )
2040  {
2041  SCIP_Real bestsolreward;
2042  SCIP_Real closedgapreward;
2043  SCIP_Real rewardcontrol = heurdata->rewardcontrol;
2044 
2045  SCIP_Real lb;
2046  SCIP_Real ub;
2047 
2048  /* the indicator function is simply 1.0 */
2049  bestsolreward = 1.0;
2050 
2051  ub = runstats->newupperbound;
2052  lb = SCIPgetLowerbound(scip);
2053 
2054  /* compute the closed gap reward */
2055  if( SCIPisEQ(scip, ub, lb) || SCIPisInfinity(scip, runstats->oldupperbound) )
2056  closedgapreward = 1.0;
2057  else
2058  {
2059  closedgapreward = (runstats->oldupperbound - ub) / (runstats->oldupperbound - lb);
2060  }
2061 
2062  /* the reward is a convex combination of the best solution reward and the reward for the closed gap */
2063  reward = rewardcontrol * bestsolreward + (1.0 - rewardcontrol) * closedgapreward;
2064 
2065  /* optionally, scale the reward by the involved effort */
2066  if( heurdata->scalebyeffort )
2067  reward /= (effort + 1.0);
2068 
2069  /* add the baseline and rescale the reward into the interval [baseline, 1.0] */
2070  reward = heurdata->rewardbaseline + (1.0 - heurdata->rewardbaseline) * reward;
2071  }
2072  else
2073  {
2074  /* linearly decrease the reward based on the number of nodes spent */
2075  SCIP_Real maxeffort = heurdata->targetnodes;
2076  SCIP_Real usednodes = runstats->usednodes;
2077 
2078  if( ndiscretevars > 0 )
2079  usednodes *= (1.0 - (runstats->nfixings / (SCIP_Real)ndiscretevars));
2080 
2081  reward = heurdata->rewardbaseline - (usednodes) * heurdata->rewardbaseline / maxeffort;
2082  reward = MAX(0.0, reward);
2083  }
2084 
2085  *rewardptr = reward;
2086  return SCIP_OKAY;
2087 }
2088 
2089 /** update internal bandit algorithm statistics for future draws */
2090 static
2092  SCIP* scip, /**< SCIP data structure */
2093  SCIP_HEURDATA* heurdata, /**< heuristic data of the ALNS neighborhood */
2094  SCIP_Real reward, /**< measured reward */
2095  int neighborhoodidx /**< the neighborhood that was chosen */
2096  )
2097 {
2098  SCIP_BANDIT* bandit;
2099  assert(scip != NULL);
2100  assert(heurdata != NULL);
2101  assert(neighborhoodidx >= 0);
2102  assert(neighborhoodidx < heurdata->nactiveneighborhoods);
2103 
2104  bandit = getBandit(heurdata);
2105 
2106  SCIPdebugMsg(scip, "Rewarding bandit algorithm action %d with reward %.2f\n", neighborhoodidx, reward);
2107  SCIP_CALL( SCIPbanditUpdate(bandit, neighborhoodidx, reward) );
2108 
2109  return SCIP_OKAY;
2110 }
2111 
2112 /** set up the sub-SCIP parameters, objective cutoff, and solution limits */
2113 static
2115  SCIP* scip, /**< SCIP data structure */
2116  SCIP* subscip, /**< sub-SCIP data structure */
2117  SCIP_VAR** subvars, /**< array of sub-SCIP variables in the order of the main SCIP */
2118  SOLVELIMITS* solvelimits, /**< pointer to solving limits data structure */
2119  SCIP_HEUR* heur, /**< this heuristic */
2120  SCIP_Bool objchgd /**< did the objective change between the source and the target SCIP? */
2121  )
2122 {
2123  SCIP_HEURDATA* heurdata;
2124  SCIP_Real cutoff;
2125  SCIP_Real upperbound;
2126 
2127  heurdata = SCIPheurGetData(heur);
2128 
2129  /* do not abort subproblem on CTRL-C */
2130  SCIP_CALL( SCIPsetBoolParam(subscip, "misc/catchctrlc", FALSE) );
2131 
2132  /* disable output to console unless we are in debug mode */
2133  SCIP_CALL( SCIPsetIntParam(subscip, "display/verblevel", 0) );
2134 
2135  /* disable statistic timing inside sub SCIP */
2136  SCIP_CALL( SCIPsetBoolParam(subscip, "timing/statistictiming", FALSE) );
2137 
2138 #ifdef ALNS_SUBSCIPOUTPUT
2139  SCIP_CALL( SCIPsetIntParam(subscip, "display/verblevel", 5) );
2140  SCIP_CALL( SCIPsetIntParam(subscip, "display/freq", 1) );
2141  /* enable statistic timing inside sub SCIP */
2142  SCIP_CALL( SCIPsetBoolParam(subscip, "timing/statistictiming", TRUE) );
2143 #endif
2144 
2145  SCIP_CALL( SCIPsetIntParam(subscip, "limits/bestsol", heurdata->nsolslim) );
2146 
2147  /* forbid recursive call of heuristics and separators solving subMIPs */
2148  if( ! heurdata->usesubscipheurs )
2149  {
2150  SCIP_CALL( SCIPsetSubscipsOff(subscip, TRUE) );
2151  }
2152 
2153  /* disable cutting plane separation */
2155 
2156  /* disable expensive presolving */
2158 
2159  /* use best estimate node selection */
2160  if( SCIPfindNodesel(subscip, "estimate") != NULL && ! SCIPisParamFixed(subscip, "nodeselection/estimate/stdpriority") )
2161  {
2162  SCIP_CALL( SCIPsetIntParam(subscip, "nodeselection/estimate/stdpriority", INT_MAX/4) );
2163  }
2164 
2165  /* use inference branching */
2166  if( SCIPfindBranchrule(subscip, "inference") != NULL && ! SCIPisParamFixed(subscip, "branching/inference/priority") )
2167  {
2168  SCIP_CALL( SCIPsetIntParam(subscip, "branching/inference/priority", INT_MAX/4) );
2169  }
2170 
2171  /* enable conflict analysis and restrict conflict pool */
2172  if( ! SCIPisParamFixed(subscip, "conflict/enable") )
2173  {
2174  SCIP_CALL( SCIPsetBoolParam(subscip, "conflict/enable", TRUE) );
2175  }
2176 
2177  if( !SCIPisParamFixed(subscip, "conflict/useboundlp") )
2178  {
2179  SCIP_CALL( SCIPsetCharParam(subscip, "conflict/useboundlp", 'o') );
2180  }
2181 
2182  if( ! SCIPisParamFixed(subscip, "conflict/maxstoresize") )
2183  {
2184  SCIP_CALL( SCIPsetIntParam(subscip, "conflict/maxstoresize", 100) );
2185  }
2186 
2187  /* speed up sub-SCIP by not checking dual LP feasibility */
2188  SCIP_CALL( SCIPsetBoolParam(subscip, "lp/checkdualfeas", FALSE) );
2189 
2190  /* employ a limit on the number of enforcement rounds in the quadratic constraint handlers; this fixes the issue that
2191  * sometimes the quadratic constraint handler needs hundreds or thousands of enforcement rounds to determine the
2192  * feasibility status of a single node without fractional branching candidates by separation (namely for uflquad
2193  * instances); however, the solution status of the sub-SCIP might get corrupted by this; hence no decutions shall be
2194  * made for the original SCIP
2195  */
2196  if( SCIPfindConshdlr(subscip, "quadratic") != NULL && ! SCIPisParamFixed(subscip, "constraints/quadratic/enfolplimit") )
2197  {
2198  SCIP_CALL( SCIPsetIntParam(subscip, "constraints/quadratic/enfolplimit", 10) );
2199  }
2200 
2201  /* add an objective cutoff */
2202  if( ! SCIPisInfinity(scip, SCIPgetUpperbound(scip)) )
2203  {
2204  upperbound = SCIPgetUpperbound(scip) - SCIPsumepsilon(scip);
2205  if( ! SCIPisInfinity(scip, -1.0 * SCIPgetLowerbound(scip)) )
2206  {
2207  cutoff = (1 - heurdata->minimprove) * SCIPgetUpperbound(scip)
2208  + heurdata->minimprove * SCIPgetLowerbound(scip);
2209  }
2210  else
2211  {
2212  if( SCIPgetUpperbound(scip) >= 0 )
2213  cutoff = (1 - heurdata->minimprove) * SCIPgetUpperbound(scip);
2214  else
2215  cutoff = (1 + heurdata->minimprove) * SCIPgetUpperbound(scip);
2216  }
2217  cutoff = MIN(upperbound, cutoff);
2218 
2219  if( SCIPisObjIntegral(scip) )
2220  cutoff = SCIPfloor(scip, cutoff);
2221 
2222  SCIPdebugMsg(scip, "Sub-SCIP cutoff: %15.9" SCIP_REAL_FORMAT " (%15.9" SCIP_REAL_FORMAT " in original space)\n",
2223  cutoff, SCIPretransformObj(scip, cutoff));
2224 
2225  /* if the objective changed between the source and the target SCIP, encode the cutoff as a constraint */
2226  if( ! objchgd )
2227  {
2228  SCIP_CALL(SCIPsetObjlimit(subscip, cutoff));
2229 
2230  SCIPdebugMsg(scip, "Cutoff added as Objective Limit\n");
2231  }
2232  else
2233  {
2234  SCIP_CONS* objcons;
2235  int nvars;
2236  SCIP_VAR** vars;
2237  int i;
2238 
2239  vars = SCIPgetVars(scip);
2240  nvars = SCIPgetNVars(scip);
2241 
2242  SCIP_CALL( SCIPcreateConsLinear(subscip, &objcons, "objbound_of_origscip", 0, NULL, NULL, -SCIPinfinity(subscip), cutoff,
2243  TRUE, TRUE, TRUE, TRUE, TRUE, FALSE, FALSE, FALSE, FALSE, FALSE) );
2244  for( i = 0; i < nvars; ++i)
2245  {
2246  if( ! SCIPisFeasZero(subscip, SCIPvarGetObj(vars[i])) )
2247  {
2248  assert(subvars[i] != NULL);
2249  SCIP_CALL( SCIPaddCoefLinear(subscip, objcons, subvars[i], SCIPvarGetObj(vars[i])) );
2250  }
2251  }
2252  SCIP_CALL( SCIPaddCons(subscip, objcons) );
2253  SCIP_CALL( SCIPreleaseCons(subscip, &objcons) );
2254 
2255  SCIPdebugMsg(scip, "Cutoff added as constraint\n");
2256  }
2257  }
2258 
2259  /* set solve limits for sub-SCIP */
2260  SCIP_CALL( setLimits(subscip, solvelimits) );
2261 
2262  /* change random seed of sub-SCIP */
2263  if( heurdata->subsciprandseeds )
2264  {
2265  SCIP_CALL( SCIPsetIntParam(subscip, "randomization/randomseedshift", (int)SCIPheurGetNCalls(heur)) );
2266  }
2267 
2268  SCIPdebugMsg(scip, "Solve Limits: %lld (%lld) nodes (stall nodes), %.1f sec., %d sols\n",
2269  solvelimits->nodelimit, solvelimits->stallnodes, solvelimits->timelimit, heurdata->nsolslim);
2270 
2271  return SCIP_OKAY;
2272 }
2273 
2274 /** execution method of primal heuristic */
2275 static
2276 SCIP_DECL_HEUREXEC(heurExecAlns)
2277 { /*lint --e{715}*/
2278  SCIP_HEURDATA* heurdata;
2279  SCIP_VAR** varbuf;
2280  SCIP_Real* valbuf;
2281  SCIP_VAR** vars;
2282  SCIP_VAR** subvars;
2283  NH_STATS runstats[NNEIGHBORHOODS];
2284  SCIP_STATUS subscipstatus[NNEIGHBORHOODS];
2285  SCIP* subscip = NULL;
2286 
2287  int nfixings;
2288  int nvars;
2289  int neighborhoodidx;
2290  int ntries;
2291  SCIP_Bool tryagain;
2292  NH* neighborhood;
2293  SOLVELIMITS solvelimits;
2294  SCIP_Bool success;
2295  SCIP_Bool run;
2296  SCIP_Bool allrewardsmode;
2297  SCIP_Real rewards[NNEIGHBORHOODS];
2298  int banditidx;
2299  int i;
2300 
2301  heurdata = SCIPheurGetData(heur);
2302  assert(heurdata != NULL);
2303 
2304  *result = SCIP_DIDNOTRUN;
2305 
2306  if( heurdata->nactiveneighborhoods == 0 )
2307  return SCIP_OKAY;
2308 
2309  /* wait for a sufficient number of nodes since last incumbent solution */
2310  if( SCIPgetDepth(scip) > 0 && SCIPgetBestSol(scip) != NULL
2311  && (SCIPgetNNodes(scip) - SCIPsolGetNodenum(SCIPgetBestSol(scip))) < heurdata->waitingnodes )
2312  {
2313  SCIPdebugMsg(scip, "Waiting nodes not satisfied\n");
2314  return SCIP_OKAY;
2315  }
2316 
2317  run = TRUE;
2318  /* check if budget allows a run of the next selected neighborhood */
2319  SCIP_CALL( determineLimits(scip, heur, &solvelimits, &run) );
2320  SCIPdebugMsg(scip, "Budget check: %" SCIP_LONGINT_FORMAT " (%" SCIP_LONGINT_FORMAT ") %s\n", solvelimits.nodelimit, heurdata->targetnodes, run ? "passed" : "must wait");
2321 
2322  if( ! run )
2323  return SCIP_OKAY;
2324 
2325  /* delay the heuristic if local reduced costs should be used for generic variable unfixing */
2326  if( heurdata->uselocalredcost && (nodeinfeasible || ! SCIPhasCurrentNodeLP(scip) || SCIPgetLPSolstat(scip) != SCIP_LPSOLSTAT_OPTIMAL) )
2327  {
2328  *result = SCIP_DELAYED;
2329 
2330  return SCIP_OKAY;
2331  }
2332 
2333  allrewardsmode = heurdata->rewardfile != NULL;
2334 
2335  /* apply some other rules for a fair all rewards mode; in normal execution mode, neighborhoods are iterated through */
2336  if( allrewardsmode )
2337  {
2338  /* most neighborhoods require an incumbent solution */
2339  if( SCIPgetNSols(scip) < 2 )
2340  {
2341  SCIPdebugMsg(scip, "Not enough solutions for all rewards mode\n");
2342  return SCIP_OKAY;
2343  }
2344 
2345  /* if the node is infeasible, or has no LP solution, which is required by some neighborhoods
2346  * if we are not in all rewards mode, the neighborhoods delay themselves individually
2347  */
2348  if( nodeinfeasible || ! SCIPhasCurrentNodeLP(scip) || SCIPgetLPSolstat(scip) != SCIP_LPSOLSTAT_OPTIMAL )
2349  {
2350  SCIPdebugMsg(scip, "Delay ALNS heuristic until a feasible node with optimally solved LP relaxation\n");
2351  *result = SCIP_DELAYED;
2352  return SCIP_OKAY;
2353  }
2354  }
2355 
2356  /* use the neighborhood that requested a delay or select the next neighborhood to run based on the selected bandit algorithm */
2357  if( heurdata->currneighborhood >= 0 )
2358  {
2359  assert(! allrewardsmode);
2360  banditidx = heurdata->currneighborhood;
2361  SCIPdebugMsg(scip, "Select delayed neighborhood %d (was delayed %d times)\n", banditidx, heurdata->ndelayedcalls);
2362  }
2363  else
2364  {
2365  SCIP_CALL( selectNeighborhood(scip, heurdata, &banditidx) );
2366  SCIPdebugMsg(scip, "Selected neighborhood %d with bandit algorithm\n", banditidx);
2367  }
2368 
2369  /* in all rewards mode, we simply loop over all heuristics */
2370  if( ! allrewardsmode )
2371  neighborhoodidx = banditidx;
2372  else
2373  neighborhoodidx = 0;
2374 
2375  assert(0 <= neighborhoodidx && neighborhoodidx < NNEIGHBORHOODS);
2376  assert(heurdata->nactiveneighborhoods > neighborhoodidx);
2377 
2378  /* allocate memory for variable fixings buffer */
2379  SCIP_CALL( SCIPgetVarsData(scip, &vars, &nvars, NULL, NULL, NULL, NULL) );
2380  SCIP_CALL( SCIPallocBufferArray(scip, &varbuf, nvars) );
2381  SCIP_CALL( SCIPallocBufferArray(scip, &valbuf, nvars) );
2382  SCIP_CALL( SCIPallocBufferArray(scip, &subvars, nvars) );
2383 
2384  /* initialize neighborhood statistics for a run */
2385  ntries = 1;
2386  do
2387  {
2388  SCIP_HASHMAP* varmapf;
2389  SCIP_EVENTHDLR* eventhdlr;
2390  SCIP_EVENTDATA eventdata;
2391  char probnamesuffix[SCIP_MAXSTRLEN];
2392  SCIP_Real allfixingrate;
2393  int ndomchgs;
2394  int nchgobjs;
2395  int naddedconss;
2396  int v;
2397  SCIP_RETCODE retcode;
2398  SCIP_RESULT fixresult;
2399 
2400  tryagain = FALSE;
2401  neighborhood = heurdata->neighborhoods[neighborhoodidx];
2402  SCIPdebugMsg(scip, "Running '%s' neighborhood %d\n", neighborhood->name, neighborhoodidx);
2403 
2404  initRunStats(scip, &runstats[neighborhoodidx]);
2405  rewards[neighborhoodidx] = 0.0;
2406 
2407  subscipstatus[neighborhoodidx] = SCIP_STATUS_UNKNOWN;
2408  SCIP_CALL( SCIPstartClock(scip, neighborhood->stats.setupclock) );
2409 
2410  /* determine variable fixings and objective coefficients of this neighborhood */
2411  SCIP_CALL( neighborhoodFixVariables(scip, heurdata, neighborhood, varbuf, valbuf, &nfixings, &fixresult) );
2412 
2413  SCIPdebugMsg(scip, "Fix %d/%d variables, result code %d\n", nfixings, nvars,fixresult);
2414 
2415  /* Fixing was not successful, either because the fixing rate was not reached (and no additional variable
2416  * prioritization was used), or the neighborhood requested a delay, e.g., because no LP relaxation solution exists
2417  * at the current node
2418  *
2419  * The ALNS heuristic keeps a delayed neighborhood active and delays itself.
2420  */
2421  if( fixresult != SCIP_SUCCESS )
2422  {
2423  SCIP_CALL( SCIPstopClock(scip, neighborhood->stats.setupclock) );
2424 
2425  /* to determine all rewards, we cannot delay neighborhoods */
2426  if( allrewardsmode )
2427  {
2428  if( ntries == heurdata->nactiveneighborhoods )
2429  break;
2430 
2431  neighborhoodidx = (neighborhoodidx + 1) % heurdata->nactiveneighborhoods;
2432  ntries++;
2433  tryagain = TRUE;
2434 
2435  continue;
2436  }
2437 
2438  /* delay the heuristic along with the selected neighborhood
2439  *
2440  * if the neighborhood has been delayed for too many consecutive calls, the delay is treated as a failure */
2441  if( fixresult == SCIP_DELAYED )
2442  {
2443  if( heurdata->ndelayedcalls > (SCIPheurGetFreq(heur) / 4 + 1) )
2444  {
2445  resetCurrentNeighborhood(heurdata);
2446 
2447  /* use SCIP_DIDNOTFIND to penalize the neighborhood with a bad reward */
2448  fixresult = SCIP_DIDNOTFIND;
2449  }
2450  else if( heurdata->currneighborhood == -1 )
2451  {
2452  heurdata->currneighborhood = neighborhoodidx;
2453  heurdata->ndelayedcalls = 1;
2454  }
2455  else
2456  {
2457  heurdata->ndelayedcalls++;
2458  }
2459  }
2460 
2461  if( fixresult == SCIP_DIDNOTRUN )
2462  {
2463  if( ntries < heurdata->nactiveneighborhoods )
2464  {
2465  SCIP_CALL( updateBanditAlgorithm(scip, heurdata, 0.0, neighborhoodidx) );
2466  SCIP_CALL( selectNeighborhood(scip, heurdata, &neighborhoodidx) );
2467  ntries++;
2468  tryagain = TRUE;
2469 
2470  SCIPdebugMsg(scip, "Neighborhood cannot run -> try next neighborhood %d\n", neighborhoodidx);
2471  continue;
2472  }
2473  else
2474  break;
2475  }
2476 
2477  assert(fixresult == SCIP_DIDNOTFIND || fixresult == SCIP_DELAYED);
2478  *result = fixresult;
2479  break;
2480  }
2481 
2482  *result = SCIP_DIDNOTFIND;
2483 
2484  neighborhood->stats.nfixings += nfixings;
2485  runstats[neighborhoodidx].nfixings = nfixings;
2486 
2487  SCIP_CALL( SCIPcreate(&subscip) );
2488  SCIP_CALL( SCIPhashmapCreate(&varmapf, SCIPblkmem(scip), nvars) );
2489  (void) SCIPsnprintf(probnamesuffix, SCIP_MAXSTRLEN, "alns_%s", neighborhood->name);
2490 
2491  /* todo later: run global propagation for this set of fixings */
2492  SCIP_CALL( SCIPcopyLargeNeighborhoodSearch(scip, subscip, varmapf, probnamesuffix, varbuf, valbuf, nfixings, FALSE, heurdata->copycuts, &success, NULL) );
2493 
2494  /* store sub-SCIP variables in array for faster access */
2495  for( v = 0; v < nvars; ++v )
2496  {
2497  subvars[v] = (SCIP_VAR*)SCIPhashmapGetImage(varmapf, (void *)vars[v]);
2498  }
2499 
2500  SCIPhashmapFree(&varmapf);
2501 
2502  /* let the neighborhood add additional constraints, or restrict domains */
2503  SCIP_CALL( neighborhoodChangeSubscip(scip, subscip, neighborhood, subvars, &ndomchgs, &nchgobjs, &naddedconss, &success) );
2504 
2505  if( ! success )
2506  {
2507  SCIP_CALL( SCIPstopClock(scip, neighborhood->stats.setupclock) );
2508 
2509  if( ! allrewardsmode || ntries == heurdata->nactiveneighborhoods )
2510  break;
2511 
2512  neighborhoodidx = (neighborhoodidx + 1) % heurdata->nactiveneighborhoods;
2513  ntries++;
2514  tryagain = TRUE;
2515 
2516  SCIP_CALL( SCIPfree(&subscip) );
2517 
2518  continue;
2519  }
2520 
2521  /* set up sub-SCIP parameters */
2522  SCIP_CALL( setupSubScip(scip, subscip, subvars, &solvelimits, heur, nchgobjs > 0) );
2523 
2524  /* copy the necessary data into the event data to create new solutions */
2525  eventdata.nodelimit = solvelimits.nodelimit; /*lint !e644*/
2526  eventdata.lplimfac = heurdata->lplimfac;
2527  eventdata.heur = heur;
2528  eventdata.sourcescip = scip;
2529  eventdata.subvars = subvars;
2530  eventdata.runstats = &runstats[neighborhoodidx];
2531  eventdata.allrewardsmode = allrewardsmode;
2532 
2533  /* include an event handler to transfer solutions into the main SCIP */
2534  SCIP_CALL( SCIPincludeEventhdlrBasic(subscip, &eventhdlr, EVENTHDLR_NAME, EVENTHDLR_DESC, eventExecAlns, NULL) );
2535 
2536  /* transform the problem before catching the events */
2537  SCIP_CALL( SCIPtransformProb(subscip) );
2538  SCIP_CALL( SCIPcatchEvent(subscip, SCIP_EVENTTYPE_ALNS, eventhdlr, &eventdata, NULL) );
2539 
2540  SCIP_CALL( SCIPstopClock(scip, neighborhood->stats.setupclock) );
2541 
2542  SCIP_CALL( SCIPstartClock(scip, neighborhood->stats.submipclock) );
2543 
2544  /* set up sub-SCIP and run presolving */
2545  retcode = SCIPpresolve(subscip);
2546  if( retcode != SCIP_OKAY )
2547  {
2548  SCIPwarningMessage(scip, "Error while presolving subproblem in ALNS heuristic; sub-SCIP terminated with code <%d>\n", retcode);
2549  SCIP_CALL( SCIPstopClock(scip, neighborhood->stats.submipclock) );
2550 
2551  SCIPABORT(); /*lint --e{527}*/
2552  break;
2553  }
2554 
2555  /* was presolving successful enough regarding fixings? otherwise, terminate */
2556  allfixingrate = (SCIPgetNOrigVars(subscip) - SCIPgetNVars(subscip)) / (SCIP_Real)SCIPgetNOrigVars(subscip);
2557 
2558  /* additional variables added in presolving may lead to the subSCIP having more variables than the original */
2559  allfixingrate = MAX(allfixingrate, 0.0);
2560 
2561  if( allfixingrate >= neighborhood->fixingrate.targetfixingrate / 2.0 )
2562  {
2563  /* run sub-SCIP for the given budget, and collect statistics */
2564  SCIP_CALL_ABORT( SCIPsolve(subscip) );
2565  }
2566  else
2567  {
2568  SCIPdebugMsg(scip, "Fixed only %.3f of all variables after presolving -> do not solve sub-SCIP\n", allfixingrate);
2569  }
2570 
2571 #ifdef ALNS_SUBSCIPOUTPUT
2572  SCIP_CALL( SCIPprintStatistics(subscip, NULL) );
2573 #endif
2574 
2575  SCIP_CALL( SCIPstopClock(scip, neighborhood->stats.submipclock) );
2576 
2577  /* update statistics based on the sub-SCIP run results */
2578  updateRunStats(&runstats[neighborhoodidx], subscip);
2579  subscipstatus[neighborhoodidx] = SCIPgetStatus(subscip);
2580  SCIPdebugMsg(scip, "Status of sub-SCIP run: %d\n", subscipstatus[neighborhoodidx]);
2581 
2582  SCIP_CALL( getReward(scip, heurdata, &runstats[neighborhoodidx], &rewards[neighborhoodidx]) );
2583 
2584  /* in all rewards mode, continue with the next neighborhood */
2585  if( allrewardsmode && ntries < heurdata->nactiveneighborhoods )
2586  {
2587  neighborhoodidx = (neighborhoodidx + 1) % heurdata->nactiveneighborhoods;
2588  ntries++;
2589  tryagain = TRUE;
2590 
2591  SCIP_CALL( SCIPfree(&subscip) );
2592  }
2593  }
2594  while( tryagain && ! SCIPisStopped(scip) );
2595 
2596  if( subscip != NULL )
2597  {
2598  SCIP_CALL( SCIPfree(&subscip) );
2599  }
2600 
2601  SCIPfreeBufferArray(scip, &subvars);
2602  SCIPfreeBufferArray(scip, &valbuf);
2603  SCIPfreeBufferArray(scip, &varbuf);
2604 
2605  /* update bandit index that may have changed unless we are in all rewards mode */
2606  if( ! allrewardsmode )
2607  banditidx = neighborhoodidx;
2608 
2609  if( *result != SCIP_DELAYED )
2610  {
2611  /* decrease the number of neighborhoods that have not been initialized */
2612  if( neighborhood->stats.nruns == 0 )
2613  --heurdata->ninitneighborhoods;
2614 
2615  heurdata->usednodes += runstats[banditidx].usednodes;
2616 
2617  /* determine the success of this neighborhood, and update the target fixing rate for the next time */
2618  updateNeighborhoodStats(&runstats[banditidx], heurdata->neighborhoods[banditidx], subscipstatus[banditidx]);
2619 
2620  /* adjust the fixing rate for this neighborhood
2621  * make no adjustments in all rewards mode, because this only affects 1 of 8 heuristics
2622  */
2623  if( heurdata->adjustfixingrate && ! allrewardsmode )
2624  {
2625  SCIPdebugMsg(scip, "Update fixing rate: %.2f\n", heurdata->neighborhoods[banditidx]->fixingrate.targetfixingrate);
2626  updateFixingRate(heurdata->neighborhoods[banditidx], subscipstatus[banditidx], &runstats[banditidx]);
2627  SCIPdebugMsg(scip, "New fixing rate: %.2f\n", heurdata->neighborhoods[banditidx]->fixingrate.targetfixingrate);
2628  }
2629  /* similarly, update the minimum improvement for the ALNS heuristic */
2630  if( heurdata->adjustminimprove )
2631  {
2632  SCIPdebugMsg(scip, "Update Minimum Improvement: %.4f\n", heurdata->minimprove);
2633  updateMinimumImprovement(heurdata, subscipstatus[banditidx], &runstats[banditidx]);
2634  SCIPdebugMsg(scip, "--> %.4f\n", heurdata->minimprove);
2635  }
2636 
2637  /* update the target node limit based on the status of the selected algorithm */
2638  if( heurdata->adjusttargetnodes && SCIPheurGetNCalls(heur) >= heurdata->nactiveneighborhoods )
2639  {
2640  updateTargetNodeLimit(heurdata, &runstats[banditidx], subscipstatus[banditidx]);
2641  }
2642 
2643  /* update the bandit algorithm by the measured reward */
2644  SCIP_CALL( updateBanditAlgorithm(scip, heurdata, rewards[banditidx], banditidx) );
2645 
2646  resetCurrentNeighborhood(heurdata);
2647  }
2648 
2649  /* write single, measured rewards and the bandit index to the reward file */
2650  if( allrewardsmode )
2651  {
2652  for( i = 0; i < heurdata->nactiveneighborhoods; ++i )
2653  {
2654  fprintf(heurdata->rewardfile, "%.4f,", rewards[i]);
2655  }
2656  fprintf(heurdata->rewardfile, "%d\n", banditidx);
2657  }
2658 
2659  return SCIP_OKAY;
2660 }
2661 
2662 /** callback to collect variable fixings of RENS */
2663 static
2664 DECL_VARFIXINGS(varFixingsRens)
2665 { /*lint --e{715}*/
2666  int nbinvars;
2667  int nintvars;
2668  SCIP_VAR** vars;
2669  int i;
2670  assert(scip != NULL);
2671  assert(varbuf != NULL);
2672  assert(nfixings != NULL);
2673  assert(valbuf != NULL);
2674 
2675  *result = SCIP_DELAYED;
2676 
2677  if( ! SCIPhasCurrentNodeLP(scip) )
2678  return SCIP_OKAY;
2680  return SCIP_OKAY;
2681 
2682  *result = SCIP_DIDNOTRUN;
2683 
2684  /* get variable information */
2685  SCIP_CALL( SCIPgetVarsData(scip, &vars, NULL, &nbinvars, &nintvars, NULL, NULL) );
2686 
2687  /* return if no binary or integer variables are present */
2688  if( nbinvars + nintvars == 0 )
2689  return SCIP_OKAY;
2690 
2691  /* loop over binary and integer variables; determine those that should be fixed in the sub-SCIP */
2692  for( i = 0; i < nbinvars + nintvars; ++i )
2693  {
2694  SCIP_VAR* var = vars[i];
2695  SCIP_Real lpsolval = SCIPvarGetLPSol(var);
2696  assert((i < nbinvars && SCIPvarIsBinary(var)) || (i >= nbinvars && SCIPvarIsIntegral(var)));
2697 
2698  /* fix all binary and integer variables with integer LP solution value */
2699  if( SCIPisFeasIntegral(scip, lpsolval) )
2700  tryAdd2variableBuffer(scip, var, lpsolval, varbuf, valbuf, nfixings, TRUE);
2701  }
2702 
2703  *result = SCIP_SUCCESS;
2704 
2705  return SCIP_OKAY;
2706 }
2707 
2708 /** callback for RENS subproblem changes */
2709 static
2710 DECL_CHANGESUBSCIP(changeSubscipRens)
2711 { /*lint --e{715}*/
2712  SCIP_VAR** vars;
2713  int nintvars;
2714  int nbinvars;
2715  int i;
2716 
2717  assert(SCIPhasCurrentNodeLP(sourcescip));
2718  assert(SCIPgetLPSolstat(sourcescip) == SCIP_LPSOLSTAT_OPTIMAL);
2719 
2720  /* get variable information */
2721  SCIP_CALL( SCIPgetVarsData(sourcescip, &vars, NULL, &nbinvars, &nintvars, NULL, NULL) );
2722 
2723  /* restrict bounds of integer variables with fractional solution value */
2724  for( i = nbinvars; i < nbinvars + nintvars; ++i )
2725  {
2726  SCIP_VAR* var = vars[i];
2727  SCIP_Real lpsolval = SCIPgetSolVal(sourcescip, NULL, var);
2728 
2729  if( subvars[i] == NULL )
2730  continue;
2731 
2732  if( ! SCIPisFeasIntegral(sourcescip, lpsolval) )
2733  {
2734  SCIP_Real newlb = SCIPfloor(sourcescip, lpsolval);
2735  SCIP_Real newub = newlb + 1.0;
2736 
2737  /* only count this as a domain change if the new lower and upper bound are a further restriction */
2738  if( newlb > SCIPvarGetLbGlobal(subvars[i]) + 0.5 || newub < SCIPvarGetUbGlobal(subvars[i]) - 0.5 )
2739  {
2740  SCIP_CALL( SCIPchgVarLbGlobal(targetscip, subvars[i], newlb) );
2741  SCIP_CALL( SCIPchgVarUbGlobal(targetscip, subvars[i], newub) );
2742  (*ndomchgs)++;
2743  }
2744  }
2745  }
2746 
2747  *success = TRUE;
2748 
2749  return SCIP_OKAY;
2750 }
2751 
2752 /** collect fixings by matching solution values in a collection of solutions for all binary and integer variables,
2753  * or for a custom set of variables
2754  */
2755 static
2757  SCIP* scip, /**< SCIP data structure */
2758  SCIP_SOL** sols, /**< array of 2 or more solutions. It is okay for the array to contain one element
2759  * equal to NULL to represent the current LP solution */
2760  int nsols, /**< number of solutions in the array */
2761  SCIP_VAR** vars, /**< variable array for which solution values must agree */
2762  int nvars, /**< number of variables, or -1 for all binary and integer variables */
2763  SCIP_VAR** varbuf, /**< buffer storage for variable fixings */
2764  SCIP_Real* valbuf, /**< buffer storage for fixing values */
2765  int* nfixings /**< pointer to store the number of fixings */
2766  )
2767 {
2768  int v;
2769  int nbinintvars;
2770  SCIP_SOL* firstsol;
2771 
2772  assert(scip != NULL);
2773  assert(sols != NULL);
2774  assert(nsols >= 2);
2775  assert(varbuf != NULL);
2776  assert(valbuf != NULL);
2777  assert(nfixings != NULL);
2778  assert(*nfixings == 0);
2779 
2780  if( nvars == -1 || vars == NULL )
2781  {
2782  int nbinvars;
2783  int nintvars;
2784  SCIP_CALL( SCIPgetVarsData(scip, &vars, NULL, &nbinvars, &nintvars, NULL, NULL) );
2785  nbinintvars = nbinvars + nintvars;
2786  nvars = nbinintvars;
2787  }
2788  firstsol = sols[0];
2789  assert(nvars > 0);
2790 
2791  /* loop over integer and binary variables and check if their solution values match in all solutions */
2792  for( v = 0; v < nvars; ++v )
2793  {
2794  SCIP_Real solval;
2795  SCIP_VAR* var;
2796  int s;
2797 
2798  var = vars[v];
2799  assert((v < SCIPgetNBinVars(scip) && SCIPvarIsBinary(var)) || (v >= SCIPgetNBinVars(scip) && SCIPvarIsIntegral(var)));
2800  solval = SCIPgetSolVal(scip, firstsol, var);
2801 
2802  /* determine if solution values match in all given solutions */
2803  for( s = 1; s < nsols; ++s )
2804  {
2805  SCIP_Real solval2 = SCIPgetSolVal(scip, sols[s], var);
2806  if( ! SCIPisEQ(scip, solval, solval2) )
2807  break;
2808  }
2809 
2810  /* if we did not break early, all solutions agree on the solution value of this variable */
2811  if( s == nsols )
2812  {
2813  tryAdd2variableBuffer(scip, var, solval, varbuf, valbuf, nfixings, TRUE);
2814  }
2815  }
2816 
2817  return SCIP_OKAY;
2818 }
2819 
2820 /** callback to collect variable fixings of RINS */
2821 static
2822 DECL_VARFIXINGS(varFixingsRins)
2824  /*lint --e{715}*/
2825  int nbinvars;
2826  int nintvars;
2827  SCIP_VAR** vars;
2828  SCIP_SOL* incumbent;
2829  SCIP_SOL* sols[2];
2830  assert(scip != NULL);
2831  assert(varbuf != NULL);
2832  assert(nfixings != NULL);
2833  assert(valbuf != NULL);
2834 
2835  *result = SCIP_DELAYED;
2836 
2837  if( ! SCIPhasCurrentNodeLP(scip) )
2838  return SCIP_OKAY;
2840  return SCIP_OKAY;
2841 
2842  *result = SCIP_DIDNOTRUN;
2843 
2844  incumbent = SCIPgetBestSol(scip);
2845  if( incumbent == NULL )
2846  return SCIP_OKAY;
2847 
2848  if( SCIPsolGetOrigin(incumbent) == SCIP_SOLORIGIN_ORIGINAL )
2849  return SCIP_OKAY;
2850 
2851  /* get variable information */
2852  SCIP_CALL( SCIPgetVarsData(scip, &vars, NULL, &nbinvars, &nintvars, NULL, NULL) );
2853 
2854  /* return if no binary or integer variables are present */
2855  if( nbinvars + nintvars == 0 )
2856  return SCIP_OKAY;
2857 
2858  sols[0] = NULL;
2859  sols[1] = incumbent;
2860 
2861  SCIP_CALL( fixMatchingSolutionValues(scip, sols, 2, vars, nbinvars + nintvars, varbuf, valbuf, nfixings) );
2862 
2863  *result = SCIP_SUCCESS;
2864 
2865  return SCIP_OKAY;
2866 }
2867 
2868 /** initialization callback for crossover when a new problem is read */
2869 static
2870 DECL_NHINIT(nhInitCrossover)
2871 { /*lint --e{715}*/
2872  DATA_CROSSOVER* data;
2873 
2874  data = neighborhood->data.crossover;
2875  assert(data != NULL);
2876 
2877  if( data->rng != NULL )
2878  SCIPfreeRandom(scip, &data->rng);
2879 
2880  data->selsol = NULL;
2881 
2882  SCIP_CALL( SCIPcreateRandom(scip, &data->rng, CROSSOVERSEED + (unsigned int)SCIPgetNVars(scip), TRUE) );
2883 
2884  return SCIP_OKAY;
2885 }
2886 
2887 /** deinitialization callback for crossover when exiting a problem */
2888 static
2889 DECL_NHEXIT(nhExitCrossover)
2890 { /*lint --e{715}*/
2891  DATA_CROSSOVER* data;
2892  data = neighborhood->data.crossover;
2893 
2894  assert(neighborhood != NULL);
2895  assert(data->rng != NULL);
2896 
2897  SCIPfreeRandom(scip, &data->rng);
2898 
2899  return SCIP_OKAY;
2900 }
2901 
2902 /** deinitialization callback for crossover before SCIP is freed */
2903 static
2904 DECL_NHFREE(nhFreeCrossover)
2905 { /*lint --e{715}*/
2906  assert(neighborhood->data.crossover != NULL);
2907  SCIPfreeBlockMemory(scip, &neighborhood->data.crossover);
2908 
2909  return SCIP_OKAY;
2910 }
2911 
2912 /** callback to collect variable fixings of crossover */
2913 static
2914 DECL_VARFIXINGS(varFixingsCrossover)
2915 { /*lint --e{715}*/
2916  DATA_CROSSOVER* data;
2917  SCIP_RANDNUMGEN* rng;
2918  SCIP_SOL** sols;
2919  SCIP_SOL** scipsols;
2920  int nsols;
2921  int lastdraw;
2922  assert(scip != NULL);
2923  assert(varbuf != NULL);
2924  assert(nfixings != NULL);
2925  assert(valbuf != NULL);
2926 
2927  data = neighborhood->data.crossover;
2928 
2929  assert(data != NULL);
2930  nsols = data->nsols;
2931  data->selsol = NULL;
2932 
2933  *result = SCIP_DIDNOTRUN;
2934 
2935  /* return if the pool has not enough solutions */
2936  if( nsols > SCIPgetNSols(scip) )
2937  return SCIP_OKAY;
2938 
2939  /* return if no binary or integer variables are present */
2940  if( SCIPgetNBinVars(scip) + SCIPgetNIntVars(scip) == 0 )
2941  return SCIP_OKAY;
2942 
2943  rng = data->rng;
2944  lastdraw = SCIPgetNSols(scip);
2945  SCIP_CALL( SCIPallocBufferArray(scip, &sols, nsols) );
2946  scipsols = SCIPgetSols(scip);
2947 
2948  /* draw as many solutions from the pool as required by crossover, biased towards
2949  * better solutions; therefore, the sorting of the solutions by objective is implicitly used
2950  */
2951  while( nsols > 0 )
2952  {
2953  /* no need for randomization anymore, exactly nsols many solutions remain for the selection */
2954  if( lastdraw == nsols )
2955  {
2956  int s;
2957 
2958  /* fill the remaining slots 0,...,nsols - 1 by the solutions at the same places */
2959  for( s = 0; s < nsols; ++s )
2960  sols[s] = scipsols[s];
2961 
2962  nsols = 0;
2963  }
2964  else
2965  {
2966  int nextdraw;
2967 
2968  assert(nsols < lastdraw);
2969 
2970  /* draw from the lastdraw - nsols many solutions nsols - 1, ... lastdraw - 1 such that nsols many solution */
2971  nextdraw = SCIPrandomGetInt(rng, nsols - 1, lastdraw - 1);
2972  assert(nextdraw >= 0);
2973 
2974  sols[nsols - 1] = scipsols[nextdraw];
2975  nsols--;
2976  lastdraw = nextdraw;
2977  }
2978  }
2979 
2980  SCIP_CALL( fixMatchingSolutionValues(scip, sols, data->nsols, NULL, -1, varbuf, valbuf, nfixings) );
2981 
2982  /* store best selected solution as reference solution */
2983  data->selsol = sols[0];
2984  assert(data->selsol != NULL);
2985 
2986  *result = SCIP_SUCCESS;
2987 
2988  SCIPfreeBufferArray(scip, &sols);
2989 
2990  return SCIP_OKAY;
2991 }
2992 
2993 /** callback for crossover reference solution */
2994 static
2995 DECL_NHREFSOL(nhRefsolCrossover)
2996 { /*lint --e{715}*/
2997  DATA_CROSSOVER* data;
2998 
2999  data = neighborhood->data.crossover;
3000 
3001  if( data->selsol != NULL )
3002  {
3003  *solptr = data->selsol;
3004  *result = SCIP_SUCCESS;
3005  }
3006  else
3007  {
3008  *result = SCIP_DIDNOTFIND;
3009  }
3010 
3011  return SCIP_OKAY;
3012 }
3013 
3014 /** initialization callback for mutation when a new problem is read */
3015 static
3016 DECL_NHINIT(nhInitMutation)
3017 { /*lint --e{715}*/
3018  DATA_MUTATION* data;
3019  assert(scip != NULL);
3020  assert(neighborhood != NULL);
3021 
3022  SCIP_CALL( SCIPallocBlockMemory(scip, &neighborhood->data.mutation) );
3023 
3024  data = neighborhood->data.mutation;
3025  assert(data != NULL);
3026 
3027  SCIP_CALL( SCIPcreateRandom(scip, &data->rng, MUTATIONSEED + (unsigned int)SCIPgetNVars(scip), TRUE) );
3028 
3029  return SCIP_OKAY;
3030 }
3031 
3032 /** deinitialization callback for mutation when exiting a problem */
3033 static
3034 DECL_NHEXIT(nhExitMutation)
3035 { /*lint --e{715}*/
3036  DATA_MUTATION* data;
3037  assert(scip != NULL);
3038  assert(neighborhood != NULL);
3039  data = neighborhood->data.mutation;
3040  assert(data != NULL);
3041 
3042  SCIPfreeRandom(scip, &data->rng);
3043 
3044  SCIPfreeBlockMemory(scip, &neighborhood->data.mutation);
3045 
3046  return SCIP_OKAY;
3047 }
3048 
3049 /** callback to collect variable fixings of mutation */
3050 static
3051 DECL_VARFIXINGS(varFixingsMutation)
3052 { /*lint --e{715}*/
3053  SCIP_RANDNUMGEN* rng;
3054 
3055  SCIP_VAR** vars;
3056  SCIP_VAR** varscpy;
3057  int i;
3058  int nvars;
3059  int nbinvars;
3060  int nintvars;
3061  int nbinintvars;
3062  int ntargetfixings;
3063  SCIP_SOL* incumbentsol;
3064  SCIP_Real targetfixingrate;
3065 
3066  assert(scip != NULL);
3067  assert(neighborhood != NULL);
3068  assert(neighborhood->data.mutation != NULL);
3069  assert(neighborhood->data.mutation->rng != NULL);
3070  rng = neighborhood->data.mutation->rng;
3071 
3072  *result = SCIP_DIDNOTRUN;
3073 
3074  /* get the problem variables */
3075  SCIP_CALL( SCIPgetVarsData(scip, &vars, &nvars, &nbinvars, &nintvars, NULL, NULL) );
3076 
3077  nbinintvars = nbinvars + nintvars;
3078  if( nbinintvars == 0 )
3079  return SCIP_OKAY;
3080 
3081  incumbentsol = SCIPgetBestSol(scip);
3082  if( incumbentsol == NULL )
3083  return SCIP_OKAY;
3084 
3085  targetfixingrate = neighborhood->fixingrate.targetfixingrate;
3086  ntargetfixings = (int)(targetfixingrate * nbinintvars) + 1;
3087 
3088  /* don't continue if number of discrete variables is too small to reach target fixing rate */
3089  if( nbinintvars <= ntargetfixings )
3090  return SCIP_OKAY;
3091 
3092  *result = SCIP_DIDNOTFIND;
3093 
3094  /* copy variables into a buffer array */
3095  SCIP_CALL( SCIPduplicateBufferArray(scip, &varscpy, vars, nbinintvars) );
3096 
3097  /* partially perturb the array until the number of target fixings is reached */
3098  for( i = 0; *nfixings < ntargetfixings && i < nbinintvars; ++i )
3099  {
3100  int randint = SCIPrandomGetInt(rng, i, nbinintvars - 1);
3101  assert(randint < nbinintvars);
3102 
3103  if( randint > i )
3104  {
3105  SCIPswapPointers((void**)&varscpy[i], (void**)&varscpy[randint]);
3106  }
3107  /* copy the selected variables and their solution values into the buffer */
3108  tryAdd2variableBuffer(scip, varscpy[i], SCIPgetSolVal(scip, incumbentsol, varscpy[i]), varbuf, valbuf, nfixings, TRUE);
3109  }
3110 
3111  assert(i == nbinintvars || *nfixings == ntargetfixings);
3112 
3113  /* Not reaching the number of target fixings means that there is a significant fraction (at least 1 - targetfixingrate)
3114  * of variables for which the incumbent solution value does not lie within the global bounds anymore. This is a nonsuccess
3115  * for the neighborhood (additional fixings are not possible), which is okay because the incumbent solution is
3116  * significantly outdated
3117  */
3118  if( *nfixings == ntargetfixings )
3119  *result = SCIP_SUCCESS;
3120 
3121  /* free the buffer array */
3122  SCIPfreeBufferArray(scip, &varscpy);
3123 
3124  return SCIP_OKAY;
3125 }
3126 
3127 /** add local branching constraint */
3128 static
3130  SCIP* sourcescip, /**< source SCIP data structure */
3131  SCIP* targetscip, /**< target SCIP data structure */
3132  SCIP_VAR** subvars, /**< array of sub SCIP variables in same order as source SCIP variables */
3133  int distance, /**< right hand side of the local branching constraint */
3134  SCIP_Bool* success, /**< pointer to store of a local branching constraint has been successfully added */
3135  int* naddedconss /**< pointer to increase the number of added constraints */
3136  )
3137 {
3138  int nbinvars;
3139  int i;
3140  SCIP_SOL* referencesol;
3141  SCIP_CONS* localbranchcons;
3142  SCIP_VAR** vars;
3143  SCIP_Real* consvals;
3144  SCIP_Real rhs;
3145 
3146  assert(sourcescip != NULL);
3147  assert(*success == FALSE);
3148 
3149  nbinvars = SCIPgetNBinVars(sourcescip);
3150  vars = SCIPgetVars(sourcescip);
3151 
3152  if( nbinvars <= 3 )
3153  return SCIP_OKAY;
3154 
3155  referencesol = SCIPgetBestSol(sourcescip);
3156  if( referencesol == NULL )
3157  return SCIP_OKAY;
3158 
3159  rhs = (SCIP_Real)distance;
3160  rhs = MAX(rhs, 2.0);
3161 
3162  SCIP_CALL( SCIPallocBufferArray(sourcescip, &consvals, nbinvars) );
3163 
3164  /* loop over binary variables and fill the local branching constraint */
3165  for( i = 0; i < nbinvars; ++i )
3166  {
3167  /* skip variables that are not present in sub-SCIP */
3168  if( subvars[i] == NULL )
3169  continue;
3170 
3171  if( SCIPisEQ(sourcescip, SCIPgetSolVal(sourcescip, referencesol, vars[i]), 0.0) )
3172  consvals[i] = 1.0;
3173  else
3174  {
3175  consvals[i] = -1.0;
3176  rhs -= 1.0;
3177  }
3178  }
3179 
3180  /* create the local branching constraint in the target scip */
3181  SCIP_CALL( SCIPcreateConsBasicLinear(targetscip, &localbranchcons, "localbranch", nbinvars, subvars, consvals, -SCIPinfinity(sourcescip), rhs) );
3182  SCIP_CALL( SCIPaddCons(targetscip, localbranchcons) );
3183  SCIP_CALL( SCIPreleaseCons(targetscip, &localbranchcons) );
3184 
3185  *naddedconss = 1;
3186  *success = TRUE;
3187 
3188  SCIPfreeBufferArray(sourcescip, &consvals);
3189 
3190  return SCIP_OKAY;
3191 }
3192 
3193 /** callback for local branching subproblem changes */
3194 static
3195 DECL_CHANGESUBSCIP(changeSubscipLocalbranching)
3196 { /*lint --e{715}*/
3197 
3198  SCIP_CALL( addLocalBranchingConstraint(sourcescip, targetscip, subvars, (int)(0.2 * SCIPgetNBinVars(sourcescip)), success, naddedconss) );
3199 
3200  return SCIP_OKAY;
3201 }
3202 
3203 /** callback for proximity subproblem changes */
3204 static
3205 DECL_CHANGESUBSCIP(changeSubscipProximity)
3206 { /*lint --e{715}*/
3207  SCIP_SOL* referencesol;
3208  SCIP_VAR** vars;
3209  int nbinvars;
3210  int nintvars;
3211  int nvars;
3212  int i;
3213 
3214  SCIP_CALL( SCIPgetVarsData(sourcescip, &vars, &nvars, &nbinvars, &nintvars, NULL, NULL) );
3215 
3216  if( nbinvars == 0 )
3217  return SCIP_OKAY;
3218 
3219  referencesol = SCIPgetBestSol(sourcescip);
3220  if( referencesol == NULL )
3221  return SCIP_OKAY;
3222 
3223  /* loop over binary variables, set objective coefficients based on reference solution in a local branching fashion */
3224  for( i = 0; i < nbinvars; ++i )
3225  {
3226  SCIP_Real newobj;
3227 
3228  /* skip variables not present in sub-SCIP */
3229  if( subvars[i] == NULL )
3230  continue;
3231 
3232  if( SCIPgetSolVal(sourcescip, referencesol, vars[i]) < 0.5 )
3233  newobj = -1.0;
3234  else
3235  newobj = 1.0;
3236  SCIP_CALL( SCIPchgVarObj(targetscip, subvars[i], newobj) );
3237  }
3238 
3239  /* loop over the remaining variables and change their objective coefficients to 0 */
3240  for( ; i < nvars; ++i )
3241  {
3242  /* skip variables not present in sub-SCIP */
3243  if( subvars[i] == NULL )
3244  continue;
3245 
3246  SCIP_CALL( SCIPchgVarObj(targetscip, subvars[i], 0.0) );
3247  }
3248 
3249  *nchgobjs = nvars;
3250  *success = TRUE;
3251 
3252  return SCIP_OKAY;
3253 }
3254 
3255 /** callback for zeroobjective subproblem changes */
3256 static
3257 DECL_CHANGESUBSCIP(changeSubscipZeroobjective)
3258 { /*lint --e{715}*/
3259  SCIP_VAR** vars;
3260  int nvars;
3261  int i;
3262 
3263  assert(*success == FALSE);
3264 
3265  SCIP_CALL( SCIPgetVarsData(sourcescip, &vars, &nvars, NULL, NULL, NULL, NULL) );
3266 
3267  /* do not run if no objective variables are present */
3268  if( SCIPgetNObjVars(sourcescip) == 0 )
3269  return SCIP_OKAY;
3270 
3271  /* loop over the variables and change their objective coefficients to 0 */
3272  for( i = 0; i < nvars; ++i )
3273  {
3274  /* skip variables not present in sub-SCIP */
3275  if( subvars[i] == NULL )
3276  continue;
3277 
3278  SCIP_CALL( SCIPchgVarObj(targetscip, subvars[i], 0.0) );
3279  }
3280 
3281  *nchgobjs = nvars;
3282  *success = TRUE;
3283 
3284  return SCIP_OKAY;
3285 }
3286 
3287 /** compute tightened bounds for integer variables depending on how much the LP and the incumbent solution values differ */
3288 static
3290  SCIP* scip, /**< SCIP data structure of the original problem */
3291  SCIP_VAR* var, /**< the variable for which bounds should be computed */
3292  SCIP_Real* lbptr, /**< pointer to store the lower bound in the DINS sub-SCIP */
3293  SCIP_Real* ubptr /**< pointer to store the upper bound in the DINS sub-SCIP */
3294  )
3295 {
3296  SCIP_Real mipsol;
3297  SCIP_Real lpsol;
3298 
3299  SCIP_Real lbglobal;
3300  SCIP_Real ubglobal;
3301  SCIP_SOL* bestsol;
3302 
3303  /* get the bounds for each variable */
3304  lbglobal = SCIPvarGetLbGlobal(var);
3305  ubglobal = SCIPvarGetUbGlobal(var);
3306 
3307  assert(SCIPvarGetType(var) == SCIP_VARTYPE_INTEGER);
3308  /* get the current LP solution for each variable */
3309  lpsol = SCIPvarGetLPSol(var);
3310 
3311  /* get the current MIP solution for each variable */
3312  bestsol = SCIPgetBestSol(scip);
3313  mipsol = SCIPgetSolVal(scip, bestsol, var);
3314 
3315  /* if the solution values differ by 0.5 or more, the variable is rebounded, otherwise it is just copied */
3316  if( REALABS(lpsol - mipsol) >= 0.5 )
3317  {
3318  SCIP_Real range;
3319 
3320  *lbptr = lbglobal;
3321  *ubptr = ubglobal;
3322 
3323  /* create an equally sized range around lpsol for general integers: bounds are lpsol +- (mipsol-lpsol) */
3324  range = 2 * lpsol - mipsol;
3325 
3326  if( mipsol >= lpsol )
3327  {
3328  range = SCIPfeasCeil(scip, range);
3329  *lbptr = MAX(*lbptr, range);
3330 
3331  /* when the bound new upper bound is equal to the current MIP solution, we set both bounds to the integral bound (without eps) */
3332  if( SCIPisFeasEQ(scip, mipsol, *lbptr) )
3333  *ubptr = *lbptr;
3334  else
3335  *ubptr = mipsol;
3336  }
3337  else
3338  {
3339  range = SCIPfeasFloor(scip, range);
3340  *ubptr = MIN(*ubptr, range);
3341 
3342  /* when the bound new upper bound is equal to the current MIP solution, we set both bounds to the integral bound (without eps) */
3343  if( SCIPisFeasEQ(scip, mipsol, *ubptr) )
3344  *lbptr = *ubptr;
3345  else
3346  *lbptr = mipsol;
3347  }
3348 
3349  /* the global domain of variables might have been reduced since incumbent was found: adjust lb and ub accordingly */
3350  *lbptr = MAX(*lbptr, lbglobal);
3351  *ubptr = MIN(*ubptr, ubglobal);
3352  }
3353  else
3354  {
3355  /* the global domain of variables might have been reduced since incumbent was found: adjust it accordingly */
3356  *lbptr = MAX(mipsol, lbglobal);
3357  *ubptr = MIN(mipsol, ubglobal);
3358  }
3359 }
3360 
3361 /** callback to collect variable fixings of DINS */
3362 static
3363 DECL_VARFIXINGS(varFixingsDins)
3365  DATA_DINS* data;
3366  SCIP_SOL* rootlpsol;
3367  SCIP_SOL** sols;
3368  int nsols;
3369  int nmipsols;
3370  int nbinvars;
3371  int nintvars;
3372  SCIP_VAR** vars;
3373  int v;
3374 
3375  data = neighborhood->data.dins;
3376  assert(data != NULL);
3377  nmipsols = SCIPgetNSols(scip);
3378  nmipsols = MIN(nmipsols, data->npoolsols);
3379 
3380  *result = SCIP_DELAYED;
3381 
3383  return SCIP_OKAY;
3384 
3385  *result = SCIP_DIDNOTRUN;
3386 
3387  if( nmipsols == 0 )
3388  return SCIP_OKAY;
3389 
3390  SCIP_CALL( SCIPgetVarsData(scip, &vars, NULL, &nbinvars, &nintvars, NULL, NULL) );
3391 
3392  if( nbinvars + nintvars == 0 )
3393  return SCIP_OKAY;
3394 
3395  SCIP_CALL( SCIPcreateSol(scip, &rootlpsol, NULL) );
3396 
3397  /* save root solution LP values in solution */
3398  for( v = 0; v < nbinvars + nintvars; ++v )
3399  {
3400  SCIP_CALL( SCIPsetSolVal(scip, rootlpsol, vars[v], SCIPvarGetRootSol(vars[v])) );
3401  }
3402 
3403  /* add the node and the root LP solution */
3404  nsols = nmipsols + 2;
3405 
3406  SCIP_CALL( SCIPallocBufferArray(scip, &sols, nsols) );
3407  sols[0] = NULL; /* node LP solution */
3408  sols[1] = rootlpsol;
3409 
3410  /* copy the remaining MIP solutions after the LP solutions */
3411  BMScopyMemoryArray(&sols[2], SCIPgetSols(scip), nmipsols); /*lint !e866*/
3412 
3413  /* 1. Binary variables are fixed if their values agree in all the solutions */
3414  if( nbinvars > 0 )
3415  {
3416  SCIP_CALL( fixMatchingSolutionValues(scip, sols, nsols, vars, nbinvars, varbuf, valbuf, nfixings) );
3417  }
3418 
3419  /* 2. Integer variables are fixed if they have a very low distance between the incumbent and the root LP solution */
3420  for( v = nbinvars; v < nintvars; ++v )
3421  {
3422  SCIP_Real lb;
3423  SCIP_Real ub;
3424  computeIntegerVariableBoundsDins(scip, vars[v], &lb, &ub);
3425 
3426  if( ub - lb < 0.5 )
3427  {
3428  assert(SCIPisFeasIntegral(scip, lb));
3429  tryAdd2variableBuffer(scip, vars[v], lb, varbuf, valbuf, nfixings, TRUE);
3430  }
3431  }
3432 
3433  *result = SCIP_SUCCESS;
3434 
3435  SCIPfreeBufferArray(scip, &sols);
3436 
3437  SCIP_CALL( SCIPfreeSol(scip, &rootlpsol) );
3438 
3439  return SCIP_OKAY;
3440 }
3441 
3442 /** callback for DINS subproblem changes */
3443 static
3444 DECL_CHANGESUBSCIP(changeSubscipDins)
3445 { /*lint --e{715}*/
3446  SCIP_VAR** vars;
3447  int nintvars;
3448  int nbinvars;
3449  int v;
3450 
3451  SCIP_CALL( SCIPgetVarsData(sourcescip, &vars, NULL, &nbinvars, &nintvars, NULL, NULL) );
3452 
3453  /* 1. loop over integer variables and tighten the bounds */
3454  for( v = nbinvars; v < nintvars; ++v )
3455  {
3456  SCIP_Real lb;
3457  SCIP_Real ub;
3458 
3459  /* skip variables not present in sub-SCIP */
3460  if( subvars[v] == NULL )
3461  continue;
3462 
3463  computeIntegerVariableBoundsDins(sourcescip, vars[v], &lb, &ub);
3464 
3465  SCIP_CALL( SCIPchgVarLbGlobal(targetscip, subvars[v], lb) );
3466  SCIP_CALL( SCIPchgVarUbGlobal(targetscip, subvars[v], ub) );
3467  ++(*ndomchgs);
3468  }
3469 
3470  /* 2. add local branching constraint for binary variables */
3471  SCIP_CALL( addLocalBranchingConstraint(sourcescip, targetscip, subvars, (int)(0.1 * SCIPgetNBinVars(sourcescip)), success, naddedconss) );
3472 
3473  *success = TRUE;
3474 
3475  return SCIP_OKAY;
3476 }
3477 
3478 /** deinitialization callback for DINS before SCIP is freed */
3479 static
3480 DECL_NHFREE(nhFreeDins)
3482  assert(neighborhood->data.dins != NULL);
3483 
3484  SCIPfreeBlockMemory(scip, &neighborhood->data.dins);
3485 
3486  return SCIP_OKAY;
3487 }
3488 
3489 /** deinitialization callback for trustregion before SCIP is freed */
3490 static
3491 DECL_NHFREE(nhFreeTrustregion)
3493  assert(neighborhood->data.trustregion != NULL);
3494 
3495  SCIPfreeBlockMemory(scip, &neighborhood->data.trustregion);
3496 
3497  return SCIP_OKAY;
3498 }
3499 
3500 /** add trust region neighborhood constraint and auxiliary objective variable */
3501 static
3502 DECL_CHANGESUBSCIP(changeSubscipTrustregion)
3503 { /*lint --e{715}*/
3504  DATA_TRUSTREGION* data;
3505 
3506  data = neighborhood->data.trustregion;
3507 
3508  /* adding the neighborhood constraint for the trust region heuristic */
3509  SCIP_CALL( SCIPaddTrustregionNeighborhoodConstraint(sourcescip, targetscip, subvars, data->violpenalty) );
3510 
3511  /* incrementing the change in objective since an additional variable is added to the objective to penalize the
3512  * violation of the trust region.
3513  */
3514  ++(*nchgobjs);
3515 
3516  return SCIP_OKAY;
3517 }
3518 
3519 /** callback that returns the incumbent solution as a reference point */
3520 static
3521 DECL_NHREFSOL(nhRefsolIncumbent)
3522 { /*lint --e{715}*/
3523  assert(scip != NULL);
3524 
3525  if( SCIPgetBestSol(scip) != NULL )
3526  {
3527  *result = SCIP_SUCCESS;
3528  *solptr = SCIPgetBestSol(scip);
3529  }
3530  else
3531  {
3532  *result = SCIP_DIDNOTFIND;
3533  }
3534 
3535  return SCIP_OKAY;
3536 }
3537 
3538 
3539 /** callback function that deactivates a neighborhood on problems with no discrete variables */
3540 static
3541 DECL_NHDEACTIVATE(nhDeactivateDiscreteVars)
3542 { /*lint --e{715}*/
3543  assert(scip != NULL);
3544  assert(deactivate != NULL);
3545 
3546  /* deactivate if no discrete variables are present */
3547  *deactivate = (SCIPgetNBinVars(scip) + SCIPgetNIntVars(scip) == 0);
3548 
3549  return SCIP_OKAY;
3550 }
3551 
3552 /** callback function that deactivates a neighborhood on problems with no binary variables */
3553 static
3554 DECL_NHDEACTIVATE(nhDeactivateBinVars)
3555 { /*lint --e{715}*/
3556  assert(scip != NULL);
3557  assert(deactivate != NULL);
3558 
3559  /* deactivate if no discrete variables are present */
3560  *deactivate = (SCIPgetNBinVars(scip) == 0);
3561 
3562  return SCIP_OKAY;
3563 }
3564 
3565 /** callback function that deactivates a neighborhood on problems with no objective variables */
3566 static
3567 DECL_NHDEACTIVATE(nhDeactivateObjVars)
3568 { /*lint --e{715}*/
3569  assert(scip != NULL);
3570  assert(deactivate != NULL);
3571 
3572  /* deactivate if no discrete variables are present */
3573  *deactivate = (SCIPgetNObjVars(scip) == 0);
3574 
3575  return SCIP_OKAY;
3576 }
3577 
3578 
3579 /** include all neighborhoods */
3580 static
3582  SCIP* scip, /**< SCIP data structure */
3583  SCIP_HEURDATA* heurdata /**< heuristic data of the ALNS heuristic */
3584  )
3585 {
3586  NH* rens;
3587  NH* rins;
3588  NH* mutation;
3589  NH* localbranching;
3590  NH* crossover;
3591  NH* proximity;
3592  NH* zeroobjective;
3593  NH* dins;
3594  NH* trustregion;
3595 
3596  heurdata->nneighborhoods = 0;
3597 
3598  /* include the RENS neighborhood */
3599  SCIP_CALL( alnsIncludeNeighborhood(scip, heurdata, &rens, "rens",
3601  varFixingsRens, changeSubscipRens, NULL, NULL, NULL, NULL, nhDeactivateDiscreteVars) );
3602 
3603  /* include the RINS neighborhood */
3604  SCIP_CALL( alnsIncludeNeighborhood(scip, heurdata, &rins, "rins",
3606  varFixingsRins, NULL, NULL, NULL, NULL, nhRefsolIncumbent, nhDeactivateDiscreteVars) );
3607 
3608  /* include the mutation neighborhood */
3609  SCIP_CALL( alnsIncludeNeighborhood(scip, heurdata, &mutation, "mutation",
3611  varFixingsMutation, NULL, nhInitMutation, nhExitMutation, NULL, nhRefsolIncumbent, nhDeactivateDiscreteVars) );
3612 
3613  /* include the local branching neighborhood */
3614  SCIP_CALL( alnsIncludeNeighborhood(scip, heurdata, &localbranching, "localbranching",
3616  NULL, changeSubscipLocalbranching, NULL, NULL, NULL, nhRefsolIncumbent, nhDeactivateBinVars) );
3617 
3618  /* include the crossover neighborhood */
3619  SCIP_CALL( alnsIncludeNeighborhood(scip, heurdata, &crossover, "crossover",
3621  varFixingsCrossover, NULL,
3622  nhInitCrossover, nhExitCrossover, nhFreeCrossover, nhRefsolCrossover, nhDeactivateDiscreteVars) );
3623 
3624  /* allocate data for crossover to include the parameter */
3625  SCIP_CALL( SCIPallocBlockMemory(scip, &crossover->data.crossover) );
3626  crossover->data.crossover->rng = NULL;
3627 
3628  /* add crossover neighborhood parameters */
3629  SCIP_CALL( SCIPaddIntParam(scip, "heuristics/alns/crossover/nsols", "the number of solutions that crossover should combine",
3630  &crossover->data.crossover->nsols, TRUE, DEFAULT_NSOLS_CROSSOVER, 2, 10, NULL, NULL) );
3631 
3632  /* include the Proximity neighborhood */
3633  SCIP_CALL( alnsIncludeNeighborhood(scip, heurdata, &proximity, "proximity",
3635  NULL, changeSubscipProximity, NULL, NULL, NULL, nhRefsolIncumbent, nhDeactivateBinVars) );
3636 
3637  /* include the Zeroobjective neighborhood */
3638  SCIP_CALL( alnsIncludeNeighborhood(scip, heurdata, &zeroobjective, "zeroobjective",
3640  NULL, changeSubscipZeroobjective, NULL, NULL, NULL, nhRefsolIncumbent, nhDeactivateObjVars) );
3641 
3642  /* include the DINS neighborhood */
3643  SCIP_CALL( alnsIncludeNeighborhood(scip, heurdata, &dins, "dins",
3645  varFixingsDins, changeSubscipDins, NULL, NULL, nhFreeDins, nhRefsolIncumbent, nhDeactivateBinVars) );
3646 
3647  /* allocate data for DINS to include the parameter */
3648  SCIP_CALL( SCIPallocBlockMemory(scip, &dins->data.dins) );
3649 
3650  /* add DINS neighborhood parameters */
3651  SCIP_CALL( SCIPaddIntParam(scip, "heuristics/alns/dins/npoolsols",
3652  "number of pool solutions where binary solution values must agree",
3653  &dins->data.dins->npoolsols, TRUE, DEFAULT_NPOOLSOLS_DINS, 1, 100, NULL, NULL) );
3654 
3655  /* include the trustregion neighborhood */
3656  SCIP_CALL( alnsIncludeNeighborhood(scip, heurdata, &trustregion, "trustregion",
3658  NULL, changeSubscipTrustregion, NULL, NULL, nhFreeTrustregion, nhRefsolIncumbent, nhDeactivateBinVars) );
3659 
3660  /* allocate data for trustregion to include the parameter */
3661  SCIP_CALL( SCIPallocBlockMemory(scip, &trustregion->data.trustregion) );
3662 
3663  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/trustregion/violpenalty",
3664  "the penalty for each change in the binary variables from the candidate solution",
3666 
3667  return SCIP_OKAY;
3668 }
3669 
3670 /** initialization method of primal heuristic (called after problem was transformed) */
3671 static
3672 SCIP_DECL_HEURINIT(heurInitAlns)
3673 { /*lint --e{715}*/
3674  SCIP_HEURDATA* heurdata;
3675  int i;
3676 
3677  assert(scip != NULL);
3678  assert(heur != NULL);
3679 
3680  heurdata = SCIPheurGetData(heur);
3681  assert(heurdata != NULL);
3682 
3683  /* reactivate all neighborhoods if a new problem is read in */
3684  heurdata->nactiveneighborhoods = heurdata->nneighborhoods;
3685 
3686  /* initialize neighborhoods for new problem */
3687  for( i = 0; i < heurdata->nneighborhoods; ++i )
3688  {
3689  NH* neighborhood = heurdata->neighborhoods[i];
3690 
3691  SCIP_CALL( neighborhoodInit(scip, neighborhood) );
3692 
3693  SCIP_CALL( resetFixingRate(scip, &neighborhood->fixingrate) );
3694 
3695  SCIP_CALL( neighborhoodStatsReset(scip, &neighborhood->stats) );
3696  }
3697 
3698  /* open reward file for reading */
3699  if( strncasecmp(heurdata->rewardfilename, DEFAULT_REWARDFILENAME, strlen(DEFAULT_REWARDFILENAME)) != 0 )
3700  {
3701  heurdata->rewardfile = fopen(heurdata->rewardfilename, "w");
3702 
3703  if( heurdata->rewardfile == NULL )
3704  {
3705  SCIPerrorMessage("Error: Could not open reward file <%s>\n", heurdata->rewardfilename);
3706  return SCIP_FILECREATEERROR;
3707  }
3708 
3709  SCIPdebugMsg(scip, "Writing reward information to <%s>\n", heurdata->rewardfilename);
3710  }
3711  else
3712  heurdata->rewardfile = NULL;
3713 
3714  return SCIP_OKAY;
3715 }
3716 
3717 
3718 /** solving process initialization method of primal heuristic (called when branch and bound process is about to begin) */
3719 static
3720 SCIP_DECL_HEURINITSOL(heurInitsolAlns)
3721 { /*lint --e{715}*/
3722  SCIP_HEURDATA* heurdata;
3723  int i;
3724  SCIP_Real* priorities;
3725  unsigned int initseed;
3726 
3727  assert(scip != NULL);
3728  assert(heur != NULL);
3729 
3730  heurdata = SCIPheurGetData(heur);
3731  assert(heurdata != NULL);
3732  heurdata->nactiveneighborhoods = heurdata->nneighborhoods;
3733 
3734  SCIP_CALL( SCIPallocBufferArray(scip, &priorities, heurdata->nactiveneighborhoods) );
3735 
3736  /* init neighborhoods for new problem by resetting their statistics and fixing rate */
3737  for( i = heurdata->nneighborhoods - 1; i >= 0; --i )
3738  {
3739  NH* neighborhood = heurdata->neighborhoods[i];
3740  SCIP_Bool deactivate;
3741 
3742  SCIP_CALL( neighborhood->nhdeactivate(scip, &deactivate) );
3743 
3744  /* disable inactive neighborhoods */
3745  if( deactivate || ! neighborhood->active )
3746  {
3747  if( heurdata->nactiveneighborhoods - 1 > i )
3748  {
3749  assert(heurdata->neighborhoods[heurdata->nactiveneighborhoods - 1]->active);
3750  SCIPswapPointers((void **)&heurdata->neighborhoods[i], (void **)&heurdata->neighborhoods[heurdata->nactiveneighborhoods - 1]);
3751  }
3752  heurdata->nactiveneighborhoods--;
3753  }
3754  }
3755 
3756  /* collect neighborhood priorities */
3757  for( i = 0; i < heurdata->nactiveneighborhoods; ++i )
3758  priorities[i] = heurdata->neighborhoods[i]->priority;
3759 
3760  initseed = (unsigned int)(heurdata->seed + SCIPgetNVars(scip));
3761 
3762  /* active neighborhoods might change between init calls, reset functionality must take this into account */
3763  if( heurdata->bandit != NULL && SCIPbanditGetNActions(heurdata->bandit) != heurdata->nactiveneighborhoods )
3764  {
3765  SCIP_CALL( SCIPfreeBandit(scip, &heurdata->bandit) );
3766 
3767  heurdata->bandit = NULL;
3768  }
3769 
3770  if( heurdata->nactiveneighborhoods > 0 )
3771  { /* create or reset bandit algorithm */
3772  if( heurdata->bandit == NULL )
3773  {
3774  SCIP_CALL( createBandit(scip, heurdata, priorities, initseed) );
3775 
3776  resetMinimumImprovement(heurdata);
3777  resetTargetNodeLimit(heurdata);
3778  }
3779  else if( heurdata->resetweights )
3780  {
3781  SCIP_CALL( SCIPresetBandit(scip, heurdata->bandit, priorities, initseed) );
3782 
3783  resetMinimumImprovement(heurdata);
3784  resetTargetNodeLimit(heurdata);
3785  }
3786  }
3787 
3788  heurdata->usednodes = 0;
3789  heurdata->ninitneighborhoods = heurdata->nactiveneighborhoods;
3790  resetCurrentNeighborhood(heurdata);
3791 
3792  SCIPfreeBufferArray(scip, &priorities);
3793 
3794  return SCIP_OKAY;
3795 }
3796 
3797 
3798 /** deinitialization method of primal heuristic (called before transformed problem is freed) */
3799 static
3800 SCIP_DECL_HEUREXIT(heurExitAlns)
3801 { /*lint --e{715}*/
3802  SCIP_HEURDATA* heurdata;
3803  int i;
3804 
3805  assert(scip != NULL);
3806  assert(heur != NULL);
3807 
3808  heurdata = SCIPheurGetData(heur);
3809  assert(heurdata != NULL);
3810 
3811  /* free neighborhood specific data */
3812  for( i = 0; i < heurdata->nneighborhoods; ++i )
3813  {
3814  NH* neighborhood = heurdata->neighborhoods[i];
3815 
3816  SCIP_CALL( neighborhoodExit(scip, neighborhood) );
3817  }
3818 
3819  if( heurdata->rewardfile != NULL )
3820  {
3821  fclose(heurdata->rewardfile);
3822  heurdata->rewardfile = NULL;
3823  }
3824 
3825  return SCIP_OKAY;
3826 }
3827 
3828 /** destructor of primal heuristic to free user data (called when SCIP is exiting) */
3829 static
3830 SCIP_DECL_HEURFREE(heurFreeAlns)
3831 { /*lint --e{715}*/
3832  SCIP_HEURDATA* heurdata;
3833  int i;
3834 
3835  assert(scip != NULL);
3836  assert(heur != NULL);
3837 
3838  heurdata = SCIPheurGetData(heur);
3839  assert(heurdata != NULL);
3840 
3841  /* bandits are only initialized if a problem has been read */
3842  if( heurdata->bandit != NULL )
3843  {
3844  SCIP_CALL( SCIPfreeBandit(scip, &heurdata->bandit) );
3845  }
3846 
3847  /* free neighborhoods */
3848  for( i = 0; i < heurdata->nneighborhoods; ++i )
3849  {
3850  SCIP_CALL( alnsFreeNeighborhood(scip, &(heurdata->neighborhoods[i])) );
3851  }
3852 
3853  SCIPfreeBlockMemoryArray(scip, &heurdata->neighborhoods, NNEIGHBORHOODS);
3854 
3855  SCIPfreeBlockMemory(scip, &heurdata);
3856 
3857  return SCIP_OKAY;
3858 }
3859 
3860 /** output method of statistics table to output file stream 'file' */
3861 static
3862 SCIP_DECL_TABLEOUTPUT(tableOutputNeighborhood)
3863 { /*lint --e{715}*/
3864  SCIP_HEURDATA* heurdata;
3865 
3866  assert(SCIPfindHeur(scip, HEUR_NAME) != NULL);
3867  heurdata = SCIPheurGetData(SCIPfindHeur(scip, HEUR_NAME));
3868  assert(heurdata != NULL);
3869 
3870  printNeighborhoodStatistics(scip, heurdata, file);
3871 
3872  return SCIP_OKAY;
3873 }
3874 
3875 /*
3876  * primal heuristic specific interface methods
3877  */
3878 
3879 /** creates the alns primal heuristic and includes it in SCIP */
3881  SCIP* scip /**< SCIP data structure */
3882  )
3883 {
3884  SCIP_HEURDATA* heurdata;
3885  SCIP_HEUR* heur;
3886 
3887  /* create alns primal heuristic data */
3888  heurdata = NULL;
3889  heur = NULL;
3890 
3891  SCIP_CALL( SCIPallocBlockMemory(scip, &heurdata) );
3892  BMSclearMemory(heurdata);
3893 
3894  /* TODO make this a user parameter? */
3895  heurdata->lplimfac = LPLIMFAC;
3896 
3897  SCIP_CALL( SCIPallocBlockMemoryArray(scip, &heurdata->neighborhoods, NNEIGHBORHOODS) );
3898 
3899  /* include primal heuristic */
3900  SCIP_CALL( SCIPincludeHeurBasic(scip, &heur,
3902  HEUR_MAXDEPTH, HEUR_TIMING, HEUR_USESSUBSCIP, heurExecAlns, heurdata) );
3903 
3904  assert(heur != NULL);
3905 
3906  /* include all neighborhoods */
3907  SCIP_CALL( includeNeighborhoods(scip, heurdata) );
3908 
3909  /* set non fundamental callbacks via setter functions */
3910  SCIP_CALL( SCIPsetHeurCopy(scip, heur, heurCopyAlns) );
3911  SCIP_CALL( SCIPsetHeurFree(scip, heur, heurFreeAlns) );
3912  SCIP_CALL( SCIPsetHeurInit(scip, heur, heurInitAlns) );
3913  SCIP_CALL( SCIPsetHeurInitsol(scip, heur, heurInitsolAlns) );
3914  SCIP_CALL( SCIPsetHeurExit(scip, heur, heurExitAlns) );
3915 
3916  /* add alns primal heuristic parameters */
3917  SCIP_CALL( SCIPaddLongintParam(scip, "heuristics/" HEUR_NAME "/maxnodes",
3918  "maximum number of nodes to regard in the subproblem",
3919  &heurdata->maxnodes, TRUE,DEFAULT_MAXNODES, 0LL, SCIP_LONGINT_MAX, NULL, NULL) );
3920 
3921  SCIP_CALL( SCIPaddLongintParam(scip, "heuristics/" HEUR_NAME "/nodesofs",
3922  "offset added to the nodes budget",
3923  &heurdata->nodesoffset, FALSE, DEFAULT_NODESOFFSET, 0LL, SCIP_LONGINT_MAX, NULL, NULL) );
3924 
3925  SCIP_CALL( SCIPaddLongintParam(scip, "heuristics/" HEUR_NAME "/minnodes",
3926  "minimum number of nodes required to start a sub-SCIP",
3927  &heurdata->minnodes, TRUE, DEFAULT_MINNODES, 0LL, SCIP_LONGINT_MAX, NULL, NULL) );
3928 
3929  SCIP_CALL( SCIPaddLongintParam(scip, "heuristics/" HEUR_NAME "/waitingnodes",
3930  "number of nodes since last incumbent solution that the heuristic should wait",
3931  &heurdata->waitingnodes, TRUE, DEFAULT_WAITINGNODES, 0LL, SCIP_LONGINT_MAX, NULL, NULL) );
3932 
3933  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/nodesquot",
3934  "fraction of nodes compared to the main SCIP for budget computation",
3935  &heurdata->nodesquot, FALSE, DEFAULT_NODESQUOT, 0.0, 1.0, NULL, NULL) );
3936 
3937  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/startminimprove",
3938  "initial factor by which ALNS should at least improve the incumbent",
3939  &heurdata->startminimprove, TRUE, DEFAULT_STARTMINIMPROVE, 0.0, 1.0, NULL, NULL) );
3940 
3941  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/minimprovelow",
3942  "lower threshold for the minimal improvement over the incumbent",
3943  &heurdata->minimprovelow, TRUE, DEFAULT_MINIMPROVELOW, 0.0, 1.0, NULL, NULL) );
3944 
3945  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/minimprovehigh",
3946  "upper bound for the minimal improvement over the incumbent",
3947  &heurdata->minimprovehigh, TRUE, DEFAULT_MINIMPROVEHIGH, 0.0, 1.0, NULL, NULL) );
3948 
3949  SCIP_CALL( SCIPaddIntParam(scip, "heuristics/" HEUR_NAME "/nsolslim",
3950  "limit on the number of improving solutions in a sub-SCIP call",
3951  &heurdata->nsolslim, FALSE, DEFAULT_NSOLSLIM, -1, INT_MAX, NULL, NULL) );
3952 
3953  SCIP_CALL( SCIPaddCharParam(scip, "heuristics/" HEUR_NAME "/banditalgo",
3954  "the bandit algorithm: (u)pper confidence bounds, (e)xp.3, epsilon (g)reedy",
3955  &heurdata->banditalgo, TRUE, DEFAULT_BANDITALGO, "ueg", NULL, NULL) );
3956 
3957  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/gamma",
3958  "weight between uniform (gamma ~ 1) and weight driven (gamma ~ 0) probability distribution for exp3",
3959  &heurdata->exp3_gamma, TRUE, DEFAULT_GAMMA, 0.0, 1.0, NULL, NULL) );
3960 
3961  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/beta",
3962  "reward offset between 0 and 1 at every observation for Exp.3",
3963  &heurdata->exp3_beta, TRUE, DEFAULT_BETA, 0.0, 1.0, NULL, NULL) );
3964 
3965  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/alpha",
3966  "parameter to increase the confidence width in UCB",
3967  &heurdata->ucb_alpha, TRUE, DEFAULT_ALPHA, 0.0, 100.0, NULL, NULL) );
3968 
3969  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/usedistances",
3970  "distances from fixed variables be used for variable prioritization",
3971  &heurdata->usedistances, TRUE, DEFAULT_USEDISTANCES, NULL, NULL) );
3972 
3973  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/useredcost",
3974  "should reduced cost scores be used for variable prioritization?",
3975  &heurdata->useredcost, TRUE, DEFAULT_USEREDCOST, NULL, NULL) );
3976 
3977  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/domorefixings",
3978  "should the ALNS heuristic do more fixings by itself based on variable prioritization "
3979  "until the target fixing rate is reached?",
3980  &heurdata->domorefixings, TRUE, DEFAULT_DOMOREFIXINGS, NULL, NULL) );
3981 
3982  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/adjustfixingrate",
3983  "should the heuristic adjust the target fixing rate based on the success?",
3984  &heurdata->adjustfixingrate, TRUE, DEFAULT_ADJUSTFIXINGRATE, NULL, NULL) );
3985 
3986  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/usesubscipheurs",
3987  "should the heuristic activate other sub-SCIP heuristics during its search?",
3988  &heurdata->usesubscipheurs, TRUE, DEFAULT_USESUBSCIPHEURS, NULL, NULL) );
3989 
3990  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/rewardcontrol",
3991  "reward control to increase the weight of the simple solution indicator and decrease the weight of the closed gap reward",
3992  &heurdata->rewardcontrol, TRUE, DEFAULT_REWARDCONTROL, 0.0, 1.0, NULL, NULL) );
3993 
3994  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/targetnodefactor",
3995  "factor by which target node number is eventually increased",
3996  &heurdata->targetnodefactor, TRUE, DEFAULT_TARGETNODEFACTOR, 1.0, 1e+5, NULL, NULL) );
3997 
3998  SCIP_CALL( SCIPaddIntParam(scip, "heuristics/" HEUR_NAME "/seed",
3999  "initial random seed for bandit algorithms and random decisions by neighborhoods",
4000  &heurdata->seed, FALSE, DEFAULT_SEED, 0, INT_MAX, NULL, NULL) );
4001 
4002  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/adjustminimprove",
4003  "should the factor by which the minimum improvement is bound be dynamically updated?",
4004  &heurdata->adjustminimprove, TRUE, DEFAULT_ADJUSTMINIMPROVE, NULL, NULL) );
4005 
4006  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/adjusttargetnodes",
4007  "should the target nodes be dynamically adjusted?",
4008  &heurdata->adjusttargetnodes, TRUE, DEFAULT_ADJUSTTARGETNODES, NULL, NULL) );
4009 
4010  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/eps",
4011  "increase exploration in epsilon-greedy bandit algorithm",
4012  &heurdata->epsgreedy_eps, TRUE, DEFAULT_EPS, 0.0, 1.0, NULL, NULL) );
4013 
4014  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/rewardbaseline",
4015  "the reward baseline to separate successful and failed calls",
4016  &heurdata->rewardbaseline, TRUE, DEFAULT_REWARDBASELINE, 0.0, 0.99, NULL, NULL) );
4017 
4018  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/resetweights",
4019  "should the bandit algorithms be reset when a new problem is read?",
4020  &heurdata->resetweights, TRUE, DEFAULT_RESETWEIGHTS, NULL, NULL) );
4021 
4022  SCIP_CALL( SCIPaddStringParam(scip, "heuristics/" HEUR_NAME "/rewardfilename", "file name to store all rewards and the selection of the bandit",
4023  &heurdata->rewardfilename, TRUE, DEFAULT_REWARDFILENAME, NULL, NULL) );
4024 
4025  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/subsciprandseeds",
4026  "should random seeds of sub-SCIPs be altered to increase diversification?",
4027  &heurdata->subsciprandseeds, TRUE, DEFAULT_SUBSCIPRANDSEEDS, NULL, NULL) );
4028 
4029  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/scalebyeffort",
4030  "should the reward be scaled by the effort?",
4031  &heurdata->scalebyeffort, TRUE, DEFAULT_SCALEBYEFFORT, NULL, NULL) );
4032 
4033  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/copycuts",
4034  "should cutting planes be copied to the sub-SCIP?",
4035  &heurdata->copycuts, TRUE, DEFAULT_COPYCUTS, NULL, NULL) );
4036 
4037  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/fixtol",
4038  "tolerance by which the fixing rate may be missed without generic fixing",
4039  &heurdata->fixtol, TRUE, DEFAULT_FIXTOL, 0.0, 1.0, NULL, NULL) );
4040 
4041  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/unfixtol",
4042  "tolerance by which the fixing rate may be exceeded without generic unfixing",
4043  &heurdata->unfixtol, TRUE, DEFAULT_UNFIXTOL, 0.0, 1.0, NULL, NULL) );
4044 
4045  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/uselocalredcost",
4046  "should local reduced costs be used for generic (un)fixing?",
4047  &heurdata->uselocalredcost, TRUE, DEFAULT_USELOCALREDCOST, NULL, NULL) );
4048 
4049  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/usepscost",
4050  "should pseudo cost scores be used for variable priorization?",
4051  &heurdata->usepscost, TRUE, DEFAULT_USEPSCOST, NULL, NULL) );
4052 
4053  assert(SCIPfindTable(scip, TABLE_NAME_NEIGHBORHOOD) == NULL);
4055  NULL, NULL, NULL, NULL, NULL, NULL, tableOutputNeighborhood,
4057 
4058  return SCIP_OKAY;
4059 }
enum SCIP_Result SCIP_RESULT
Definition: type_result.h:52
#define DEFAULT_BANDITALGO
Definition: heur_alns.c:106
SCIP_Real targetfixingrate
Definition: heur_alns.c:340
SCIP_Bool SCIPisEQ(SCIP *scip, SCIP_Real val1, SCIP_Real val2)
#define SCIPfreeBlockMemoryArray(scip, ptr, num)
Definition: scip_mem.h:97
#define DEFAULT_GAMMA
Definition: heur_alns.c:123
SCIP_Longint SCIPheurGetNCalls(SCIP_HEUR *heur)
Definition: heur.c:1555
NH_STATS stats
Definition: heur_alns.c:350
SCIP_RETCODE SCIPfreeBandit(SCIP *scip, SCIP_BANDIT **bandit)
Definition: scip_bandit.c:98
public methods for the epsilon greedy bandit selector
#define DEFAULT_USESUBSCIPHEURS
Definition: heur_alns.c:136
SCIP_RETCODE SCIPcreateConsLinear(SCIP *scip, SCIP_CONS **cons, const char *name, int nvars, SCIP_VAR **vars, SCIP_Real *vals, SCIP_Real lhs, SCIP_Real rhs, 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)
#define DEFAULT_RESETWEIGHTS
Definition: heur_alns.c:109
static SCIP_DECL_TABLEOUTPUT(tableOutputNeighborhood)
Definition: heur_alns.c:3863
SCIP_RETCODE SCIPfreeSol(SCIP *scip, SCIP_SOL **sol)
Definition: scip_sol.c:977
SCIP_RETCODE SCIPcreateBanditEpsgreedy(SCIP *scip, SCIP_BANDIT **epsgreedy, SCIP_Real *priorities, SCIP_Real eps, SCIP_Bool preferrecent, SCIP_Real decayfactor, int avglim, int nactions, unsigned int initseed)
static SCIP_RETCODE addLocalBranchingConstraint(SCIP *sourcescip, SCIP *targetscip, SCIP_VAR **subvars, int distance, SCIP_Bool *success, int *naddedconss)
Definition: heur_alns.c:3130
int nfixings
Definition: heur_alns.c:331
SCIP_RETCODE SCIPincludeHeurAlns(SCIP *scip)
Definition: heur_alns.c:3881
SCIP_RETCODE SCIPincludeTable(SCIP *scip, const char *name, const char *desc, SCIP_Bool active, SCIP_DECL_TABLECOPY((*tablecopy)), SCIP_DECL_TABLEFREE((*tablefree)), SCIP_DECL_TABLEINIT((*tableinit)), SCIP_DECL_TABLEEXIT((*tableexit)), SCIP_DECL_TABLEINITSOL((*tableinitsol)), SCIP_DECL_TABLEEXITSOL((*tableexitsol)), SCIP_DECL_TABLEOUTPUT((*tableoutput)), SCIP_TABLEDATA *tabledata, int position, SCIP_STAGE earlieststage)
Definition: scip_table.c:47
#define SCIP_EVENTTYPE_LPSOLVED
Definition: type_event.h:92
SCIP_Real oldupperbound
Definition: heur_alns.c:325
int nruns
Definition: heur_alns.c:327
SCIP_Bool SCIPisStopped(SCIP *scip)
Definition: scip_general.c:687
SCIP_Real SCIPsumepsilon(SCIP *scip)
#define DEFAULT_STARTMINIMPROVE
Definition: heur_alns.c:98
#define SCIPallocBlockMemoryArray(scip, ptr, num)
Definition: scip_mem.h:80
static SCIP_RETCODE createBandit(SCIP *scip, SCIP_HEURDATA *heurdata, SCIP_Real *priorities, unsigned int initseed)
Definition: heur_alns.c:1557
SCIP_RETCODE SCIPresetClock(SCIP *scip, SCIP_CLOCK *clck)
Definition: scip_timing.c:135
SCIP_CONSHDLR * SCIPfindConshdlr(SCIP *scip, const char *name)
Definition: scip_cons.c:877
const char * SCIPheurGetName(SCIP_HEUR *heur)
Definition: heur.c:1429
SCIP_RETCODE SCIPsetSolVal(SCIP *scip, SCIP_SOL *sol, SCIP_VAR *var, SCIP_Real val)
Definition: scip_sol.c:1213
public methods for SCIP parameter handling
int SCIPheurGetFreq(SCIP_HEUR *heur)
Definition: heur.c:1514
HistIndex
Definition: heur_alns.c:305
#define HEUR_DISPCHAR
Definition: heur_alns.c:69
#define DEFAULT_REWARDBASELINE
Definition: heur_alns.c:111
SCIP_Real * pscostscores
Definition: heur_alns.c:477
void SCIPfreeRandom(SCIP *scip, SCIP_RANDNUMGEN **randnumgen)
public methods for node selector plugins
SCIP_SOL * selsol
Definition: heur_alns.c:380
#define DEFAULT_MAXFIXINGRATE_LOCALBRANCHING
Definition: heur_alns.c:162
static void updateMinimumImprovement(SCIP_HEURDATA *heurdata, SCIP_STATUS subscipstatus, NH_STATS *runstats)
Definition: heur_alns.c:693
public methods for memory management
enum HistIndex HISTINDEX
Definition: heur_alns.c:315
static SCIP_RETCODE alnsUnfixVariables(SCIP *scip, SCIP_HEURDATA *heurdata, SCIP_VAR **varbuf, SCIP_Real *valbuf, int *nfixings, int ntargetfixings, SCIP_Bool *success)
Definition: heur_alns.c:1613
static void decreaseMinimumImprovement(SCIP_HEURDATA *heurdata)
Definition: heur_alns.c:680
SCIP_HEURDATA * SCIPheurGetData(SCIP_HEUR *heur)
Definition: heur.c:1340
SCIP_STATUS SCIPgetStatus(SCIP *scip)
Definition: scip_general.c:467
SCIP_RETCODE SCIPtranslateSubSol(SCIP *scip, SCIP *subscip, SCIP_SOL *subsol, SCIP_HEUR *heur, SCIP_VAR **subvars, SCIP_SOL **newsol)
Definition: scip_copy.c:1356
DATA_DINS * dins
Definition: heur_alns.c:364
SCIP_Real SCIPgetVarRedcost(SCIP *scip, SCIP_VAR *var)
Definition: scip_var.c:1861
SCIP_RETCODE SCIPinterruptSolve(SCIP *scip)
Definition: scip_solve.c:3435
static void resetMinimumImprovement(SCIP_HEURDATA *heurdata)
Definition: heur_alns.c:658
#define DECL_NHINIT(x)
Definition: heur_alns.c:266
#define HEUR_FREQ
Definition: heur_alns.c:71
#define SCIP_MAXSTRLEN
Definition: def.h:279
#define DEFAULT_NSOLSLIM
Definition: heur_alns.c:84
static SCIP_DECL_HEURINIT(heurInitAlns)
Definition: heur_alns.c:3673
#define DEFAULT_ACTIVE_CROSSOVER
Definition: heur_alns.c:173
void SCIPwarningMessage(SCIP *scip, const char *formatstr,...)
Definition: scip_message.c:123
#define DEFAULT_PRIORITY_PROXIMITY
Definition: heur_alns.c:169
#define HEUR_TIMING
Definition: heur_alns.c:74
static SCIP_RETCODE alnsIncludeNeighborhood(SCIP *scip, SCIP_HEURDATA *heurdata, NH **neighborhood, const char *name, SCIP_Real minfixingrate, SCIP_Real maxfixingrate, SCIP_Bool active, SCIP_Real priority, DECL_VARFIXINGS((*varfixings)), DECL_CHANGESUBSCIP((*changesubscip)), DECL_NHINIT((*nhinit)), DECL_NHEXIT((*nhexit)), DECL_NHFREE((*nhfree)), DECL_NHREFSOL((*nhrefsol)), DECL_NHDEACTIVATE((*nhdeactivate)))
Definition: heur_alns.c:767
#define DEFAULT_PRIORITY_DINS
Definition: heur_alns.c:184
SCIP_EXPORT SCIP_Real SCIPvarGetLPSol(SCIP_VAR *var)
Definition: var.c:18041
SCIP_RETCODE SCIPcreateClock(SCIP *scip, SCIP_CLOCK **clck)
Definition: scip_timing.c:67
SCIP_Real SCIPgetSolVal(SCIP *scip, SCIP_SOL *sol, SCIP_VAR *var)
Definition: scip_sol.c:1353
#define DEFAULT_USEREDCOST
Definition: heur_alns.c:127
public solving methods
static void updateNeighborhoodStats(NH_STATS *runstats, NH *neighborhood, SCIP_STATUS subscipstatus)
Definition: heur_alns.c:1132
SCIP * scip
Definition: heur_alns.c:473
SCIP_RETCODE SCIPaddCoefLinear(SCIP *scip, SCIP_CONS *cons, SCIP_VAR *var, SCIP_Real val)
public methods for timing
SCIP_RETCODE SCIPtransformProb(SCIP *scip)
Definition: scip_solve.c:357
static SCIP_RETCODE updateBanditAlgorithm(SCIP *scip, SCIP_HEURDATA *heurdata, SCIP_Real reward, int neighborhoodidx)
Definition: heur_alns.c:2092
#define DECL_VARFIXINGS(x)
Definition: heur_alns.c:237
#define DEFAULT_ACTIVE_RINS
Definition: heur_alns.c:153
#define NNEIGHBORHOODS
Definition: heur_alns.c:77
DATA_CROSSOVER * crossover
Definition: heur_alns.c:363
SCIP_RETCODE SCIPcreateBanditExp3(SCIP *scip, SCIP_BANDIT **exp3, SCIP_Real *priorities, SCIP_Real gammaparam, SCIP_Real beta, int nactions, unsigned int initseed)
Definition: bandit_exp3.c:302
#define TABLE_DESC_NEIGHBORHOOD
Definition: heur_alns.c:203
#define DECL_NHREFSOL(x)
Definition: heur_alns.c:291
SCIP_EXPORT SCIP_Bool SCIPvarIsBinary(SCIP_VAR *var)
Definition: var.c:17197
SCIP_RETCODE SCIPvariablegraphBreadthFirst(SCIP *scip, SCIP_VGRAPH *vargraph, SCIP_VAR **startvars, int nstartvars, int *distances, int maxdistance, int maxvars, int maxbinintvars)
Definition: heur.c:1666
const char * SCIPeventhdlrGetName(SCIP_EVENTHDLR *eventhdlr)
Definition: event.c:315
int SCIPgetNVars(SCIP *scip)
Definition: scip_prob.c:1986
#define LPLIMFAC
Definition: heur_alns.c:90
SCIP_Real SCIPgetSolvingTime(SCIP *scip)
Definition: scip_timing.c:360
#define FALSE
Definition: def.h:73
#define DEFAULT_ACTIVE_LOCALBRANCHING
Definition: heur_alns.c:163
SCIP_EXPORT SCIP_Real SCIPvarGetObj(SCIP_VAR *var)
Definition: var.c:17515
#define DEFAULT_NODESOFFSET
Definition: heur_alns.c:83
SCIP_Real SCIPrandomGetReal(SCIP_RANDNUMGEN *randnumgen, SCIP_Real minrandval, SCIP_Real maxrandval)
Definition: misc.c:9981
SCIP_RETCODE SCIPcreateConsBasicLinear(SCIP *scip, SCIP_CONS **cons, const char *name, int nvars, SCIP_VAR **vars, SCIP_Real *vals, SCIP_Real lhs, SCIP_Real rhs)
SCIP_EXPORT SCIP_VARTYPE SCIPvarGetType(SCIP_VAR *var)
Definition: var.c:17182
SCIP_Bool SCIPisFeasNegative(SCIP *scip, SCIP_Real val)
#define TRUE
Definition: def.h:72
SCIP_Longint stallnodes
Definition: heur_alns.c:465
#define DEFAULT_PRIORITY_RINS
Definition: heur_alns.c:154
enum SCIP_Retcode SCIP_RETCODE
Definition: type_retcode.h:54
methods commonly used by primal heuristics
#define DEFAULT_ACTIVE_PROXIMITY
Definition: heur_alns.c:168
#define DEFAULT_MINFIXINGRATE_PROXIMITY
Definition: heur_alns.c:166
#define DEFAULT_WAITINGNODES
Definition: heur_alns.c:87
NH_FIXINGRATE fixingrate
Definition: heur_alns.c:349
#define DEFAULT_NODESQUOT
Definition: heur_alns.c:82
SCIP_RETCODE SCIPsolve(SCIP *scip)
Definition: scip_solve.c:2555
#define DEFAULT_VIOLPENALTY_TRUSTREGION
Definition: heur_alns.c:194
#define DEFAULT_MINIMPROVELOW
Definition: heur_alns.c:95
#define DECL_NHFREE(x)
Definition: heur_alns.c:278
void * SCIPhashmapGetImage(SCIP_HASHMAP *hashmap, void *origin)
Definition: misc.c:3201
struct SCIP_HeurData SCIP_HEURDATA
Definition: type_heur.h:67
public methods for problem variables
static GRAPHNODE ** active
static SCIP_RETCODE neighborhoodFixVariables(SCIP *scip, SCIP_HEURDATA *heurdata, NH *neighborhood, SCIP_VAR **varbuf, SCIP_Real *valbuf, int *nfixings, SCIP_RESULT *result)
Definition: heur_alns.c:1760
static SCIP_DECL_HEUREXIT(heurExitAlns)
Definition: heur_alns.c:3801
SCIP_RETCODE SCIPaddBoolParam(SCIP *scip, const char *name, const char *desc, SCIP_Bool *valueptr, SCIP_Bool isadvanced, SCIP_Bool defaultvalue, SCIP_DECL_PARAMCHGD((*paramchgd)), SCIP_PARAMDATA *paramdata)
Definition: scip_param.c:48
#define SCIPfreeBlockMemory(scip, ptr)
Definition: scip_mem.h:95
SCIP_Longint SCIPgetMemUsed(SCIP *scip)
Definition: scip_mem.c:91
#define DEFAULT_REWARDFILENAME
Definition: heur_alns.c:138
#define DEFAULT_MAXFIXINGRATE_DINS
Definition: heur_alns.c:182
#define SCIPdebugMessage
Definition: pub_message.h:87
SCIP_Real timelimit
Definition: heur_alns.c:464
#define HEUR_NAME
Definition: heur_alns.c:67
SCIP_EXPORT SCIP_VARSTATUS SCIPvarGetStatus(SCIP_VAR *var)
Definition: var.c:17136
#define DEFAULT_MINFIXINGRATE_RENS
Definition: heur_alns.c:146
static SCIP_RETCODE alnsFixMoreVariables(SCIP *scip, SCIP_HEURDATA *heurdata, SCIP_SOL *refsol, SCIP_VAR **varbuf, SCIP_Real *valbuf, int *nfixings, int ntargetfixings, SCIP_Bool *success)
Definition: heur_alns.c:1387
SCIP_RETCODE SCIPsetSubscipsOff(SCIP *scip, SCIP_Bool quiet)
Definition: scip_param.c:899
#define SCIPduplicateBufferArray(scip, ptr, source, num)
Definition: scip_mem.h:119
SCIP_Real SCIPgetUpperbound(SCIP *scip)
DATA_TRUSTREGION * trustregion
Definition: heur_alns.c:365
#define SCIP_LONGINT_MAX
Definition: def.h:149
SCIP_EXPORT SCIP_Real SCIPvarGetBestRootSol(SCIP_VAR *var)
Definition: var.c:13483
#define SCIPfreeBufferArray(scip, ptr)
Definition: scip_mem.h:123
#define DEFAULT_UNFIXTOL
Definition: heur_alns.c:113
#define SCIPallocBlockMemory(scip, ptr)
Definition: scip_mem.h:78
public methods for SCIP variables
SCIP_RETCODE SCIPsetHeurInit(SCIP *scip, SCIP_HEUR *heur, SCIP_DECL_HEURINIT((*heurinit)))
Definition: scip_heur.c:185
Definition: heur_alns.c:346
SCIP_RETCODE SCIPpresolve(SCIP *scip)
Definition: scip_solve.c:2393
#define SCIP_EVENTTYPE_ALNS
Definition: heur_alns.c:199
SCIP_RETCODE SCIPbanditSelect(SCIP_BANDIT *bandit, int *action)
Definition: bandit.c:144
SCIP_Real violpenalty
Definition: heur_alns.c:391
#define SCIPdebugMsg
Definition: scip_message.h:69
SCIP_Real SCIPgetCutoffbound(SCIP *scip)
SCIP_Bool SCIPisFeasIntegral(SCIP *scip, SCIP_Real val)
SCIP_LPSOLSTAT SCIPgetLPSolstat(SCIP *scip)
Definition: scip_lp.c:159
#define DEFAULT_PRIORITY_ZEROOBJECTIVE
Definition: heur_alns.c:179
SCIP_Real SCIPgetClockTime(SCIP *scip, SCIP_CLOCK *clck)
Definition: scip_timing.c:301
SCIP_Bool SCIPisTransformed(SCIP *scip)
Definition: scip_general.c:559
#define LRATEMIN
Definition: heur_alns.c:89
SCIP_Longint SCIPheurGetNBestSolsFound(SCIP_HEUR *heur)
Definition: heur.c:1575
SCIP_Bool SCIPhasCurrentNodeLP(SCIP *scip)
Definition: scip_lp.c:74
SCIP_Bool SCIPisDualfeasNegative(SCIP *scip, SCIP_Real val)
SCIP_Bool SCIPisInfinity(SCIP *scip, SCIP_Real val)
#define DEFAULT_ADJUSTFIXINGRATE
Definition: heur_alns.c:133
int SCIPgetNIntVars(SCIP *scip)
Definition: scip_prob.c:2076
static SCIP_RETCODE alnsFreeNeighborhood(SCIP *scip, NH **neighborhood)
Definition: heur_alns.c:830
public methods for numerical tolerances
SCIP_Bool SCIPisDualfeasZero(SCIP *scip, SCIP_Real val)
SCIP_RETCODE SCIPcreateRandom(SCIP *scip, SCIP_RANDNUMGEN **randnumgen, unsigned int initialseed, SCIP_Bool useglobalseed)
SCIP_HEUR * SCIPfindHeur(SCIP *scip, const char *name)
Definition: scip_heur.c:249
SCIP_RETCODE SCIPcreateSol(SCIP *scip, SCIP_SOL **sol, SCIP_HEUR *heur)
Definition: scip_sol.c:320
SCIP_Longint SCIPgetNLPs(SCIP *scip)
static void updateTargetNodeLimit(SCIP_HEURDATA *heurdata, NH_STATS *runstats, SCIP_STATUS subscipstatus)
Definition: heur_alns.c:621
#define HEUR_USESSUBSCIP
Definition: heur_alns.c:75
#define SCIP_REAL_FORMAT
Definition: def.h:166
SCIP_RETCODE SCIPcopyLargeNeighborhoodSearch(SCIP *sourcescip, SCIP *subscip, SCIP_HASHMAP *varmap, const char *suffix, SCIP_VAR **fixedvars, SCIP_Real *fixedvals, int nfixedvars, SCIP_Bool uselprows, SCIP_Bool copycuts, SCIP_Bool *success, SCIP_Bool *valid)
Definition: heuristics.c:916
SCIP_RETCODE SCIPsetObjlimit(SCIP *scip, SCIP_Real objlimit)
Definition: scip_prob.c:1420
public methods for querying solving statistics
int SCIPgetNSols(SCIP *scip)
Definition: scip_sol.c:2206
SCIP_EXPORT SCIP_Real SCIPvarGetRootSol(SCIP_VAR *var)
Definition: var.c:13119
SCIP_RETCODE SCIPbanditUpdate(SCIP_BANDIT *bandit, int action, SCIP_Real score)
Definition: bandit.c:165
SCIP_RETCODE SCIPsetRealParam(SCIP *scip, const char *name, SCIP_Real value)
Definition: scip_param.c:619
#define DEFAULT_ACTIVE_RENS
Definition: heur_alns.c:148
SCIP_RETCODE SCIPincludeHeurBasic(SCIP *scip, SCIP_HEUR **heur, const char *name, const char *desc, char dispchar, int priority, int freq, int freqofs, int maxdepth, SCIP_HEURTIMING timingmask, SCIP_Bool usessubscip, SCIP_DECL_HEUREXEC((*heurexec)), SCIP_HEURDATA *heurdata)
Definition: scip_heur.c:108
public methods for the branch-and-bound tree
static void increaseTargetNodeLimit(SCIP_HEURDATA *heurdata)
Definition: heur_alns.c:599
#define DEFAULT_USEDISTANCES
Definition: heur_alns.c:129
#define DEFAULT_MINIMPROVEHIGH
Definition: heur_alns.c:96
static void updateRunStats(NH_STATS *stats, SCIP *subscip)
Definition: heur_alns.c:1023
SCIP_Longint SCIPgetNNodes(SCIP *scip)
SCIP_Real increment
Definition: heur_alns.c:341
#define DEFAULT_PRIORITY_LOCALBRANCHING
Definition: heur_alns.c:164
#define TABLE_POSITION_NEIGHBORHOOD
Definition: heur_alns.c:204
#define DEFAULT_ADJUSTTARGETNODES
Definition: heur_alns.c:100
#define DEFAULT_MINFIXINGRATE_RINS
Definition: heur_alns.c:151
static void resetCurrentNeighborhood(SCIP_HEURDATA *heurdata)
Definition: heur_alns.c:506
SCIP_RETCODE SCIPcreate(SCIP **scip)
Definition: scip_general.c:283
#define SCIP_EVENTTYPE_SOLFOUND
Definition: type_event.h:135
SCIP_Real memorylimit
Definition: heur_alns.c:463
static SCIP_RETCODE neighborhoodStatsReset(SCIP *scip, NH_STATS *stats)
Definition: heur_alns.c:742
static void increaseFixingRate(NH_FIXINGRATE *fx)
Definition: heur_alns.c:531
SCIP_Bool SCIPisObjIntegral(SCIP *scip)
Definition: scip_prob.c:1560
SCIP_EXPORT const char * SCIPvarGetName(SCIP_VAR *var)
Definition: var.c:17017
#define BMSfreeMemoryArray(ptr)
Definition: memory.h:139
SCIP_EXPORT SCIP_Bool SCIPvarIsIntegral(SCIP_VAR *var)
Definition: var.c:17208
#define SCIPerrorMessage
Definition: pub_message.h:55
DATA_MUTATION * mutation
Definition: heur_alns.c:362
static SCIP_DECL_HEURCOPY(heurCopyAlns)
Definition: heur_alns.c:1595
#define DECL_NHDEACTIVATE(x)
Definition: heur_alns.c:299
SCIP_BRANCHRULE * SCIPfindBranchrule(SCIP *scip, const char *name)
Definition: scip_branch.c:288
#define DEFAULT_MINFIXINGRATE_DINS
Definition: heur_alns.c:181
SCIP_Real * redcostscores
Definition: heur_alns.c:476
public methods for event handler plugins and event handlers
SCIP_Bool SCIPisFeasEQ(SCIP *scip, SCIP_Real val1, SCIP_Real val2)
SCIP_RETCODE SCIPcatchEvent(SCIP *scip, SCIP_EVENTTYPE eventtype, SCIP_EVENTHDLR *eventhdlr, SCIP_EVENTDATA *eventdata, int *filterpos)
Definition: scip_event.c:277
int SCIPgetNObjVars(SCIP *scip)
Definition: scip_prob.c:2214
char * name
Definition: heur_alns.c:348
SCIP_VAR ** SCIPgetVars(SCIP *scip)
Definition: scip_prob.c:1941
SCIP_EXPORT SCIP_SOLORIGIN SCIPsolGetOrigin(SCIP_SOL *sol)
Definition: sol.c:2511
static SCIP_DECL_HEURFREE(heurFreeAlns)
Definition: heur_alns.c:3831
union Nh::@4 data
BMS_BLKMEM * SCIPblkmem(SCIP *scip)
Definition: scip_mem.c:48
#define DEFAULT_MINNODES
Definition: heur_alns.c:85
SCIP_CLOCK * submipclock
Definition: heur_alns.c:323
#define FIXINGRATE_DECAY
Definition: heur_alns.c:134
#define DEFAULT_ACTIVE_ZEROOBJECTIVE
Definition: heur_alns.c:178
struct SCIP_EventData SCIP_EVENTDATA
Definition: type_event.h:164
static SCIP_DECL_SORTINDCOMP(sortIndCompAlns)
Definition: heur_alns.c:1172
#define DEFAULT_ALPHA
Definition: heur_alns.c:122
static SCIP_DECL_HEURINITSOL(heurInitsolAlns)
Definition: heur_alns.c:3721
#define NULL
Definition: lpi_spx1.cpp:155
SCIP_TABLE * SCIPfindTable(SCIP *scip, const char *name)
Definition: scip_table.c:85
#define DEFAULT_MAXFIXINGRATE_RENS
Definition: heur_alns.c:147
SCIP_RANDNUMGEN * rng
Definition: heur_alns.c:379
#define EVENTHDLR_DESC
Definition: heur_alns.c:198
#define REALABS(x)
Definition: def.h:187
#define HEUR_FREQOFS
Definition: heur_alns.c:72
public methods for problem copies
public methods for primal CIP solutions
Adaptive large neighborhood search heuristic that orchestrates popular LNS heuristics.
static SCIP_RETCODE neighborhoodInit(SCIP *scip, NH *neighborhood)
Definition: heur_alns.c:861
SCIP_NODESEL * SCIPfindNodesel(SCIP *scip, const char *name)
Definition: scip_nodesel.c:225
#define SCIP_CALL(x)
Definition: def.h:370
SCIP_RETCODE SCIPsetPresolving(SCIP *scip, SCIP_PARAMSETTING paramsetting, SCIP_Bool quiet)
Definition: scip_param.c:948
#define DEFAULT_SUBSCIPRANDSEEDS
Definition: heur_alns.c:110
SCIP_RETCODE SCIPsetCharParam(SCIP *scip, const char *name, char value)
Definition: scip_param.c:677
SCIP_EVENTTYPE SCIPeventGetType(SCIP_EVENT *event)
Definition: event.c:1021
static void updateFixingRate(NH *neighborhood, SCIP_STATUS subscipstatus, NH_STATS *runstats)
Definition: heur_alns.c:554
SCIP_RETCODE SCIPaddStringParam(SCIP *scip, const char *name, const char *desc, char **valueptr, SCIP_Bool isadvanced, const char *defaultvalue, SCIP_DECL_PARAMCHGD((*paramchgd)), SCIP_PARAMDATA *paramdata)
Definition: scip_param.c:185
SCIP_Longint nodelimit
Definition: heur_alns.c:462
unsigned int useredcost
Definition: heur_alns.c:478
SCIP_Longint nbestsolsfound
Definition: heur_alns.c:330
#define DEFAULT_PRIORITY_MUTATION
Definition: heur_alns.c:159
static SCIP_Real getVariableRedcostScore(SCIP *scip, SCIP_VAR *var, SCIP_Real refsolval, SCIP_Bool uselocalredcost)
Definition: heur_alns.c:1241
int SCIPgetNOrigVars(SCIP *scip)
Definition: scip_prob.c:2426
SCIP_RETCODE SCIPresetBandit(SCIP *scip, SCIP_BANDIT *bandit, SCIP_Real *priorities, unsigned int seed)
Definition: scip_bandit.c:82
SCIP_RANDNUMGEN * SCIPbanditGetRandnumgen(SCIP_BANDIT *bandit)
Definition: bandit.c:284
SCIP_Real SCIPfeasFloor(SCIP *scip, SCIP_Real val)
#define DEFAULT_MAXNODES
Definition: heur_alns.c:86
static void updateFixingRateIncrement(NH_FIXINGRATE *fx)
Definition: heur_alns.c:517
SCIP_CLOCK * setupclock
Definition: heur_alns.c:322
#define BMSduplicateMemoryArray(ptr, source, num)
Definition: memory.h:135
public methods for primal heuristic plugins and divesets
public methods for constraint handler plugins and constraints
#define DEFAULT_MINFIXINGRATE_TRUSTREGION
Definition: heur_alns.c:186
SCIP_RETCODE SCIPgetRealParam(SCIP *scip, const char *name, SCIP_Real *value)
Definition: scip_param.c:298
SCIP_Bool SCIPisFeasZero(SCIP *scip, SCIP_Real val)
SCIP_Real newupperbound
Definition: heur_alns.c:326
#define SCIPallocBufferArray(scip, ptr, num)
Definition: scip_mem.h:111
#define DEFAULT_USEPSCOST
Definition: heur_alns.c:128
SCIP_Real SCIPinfinity(SCIP *scip)
public data structures and miscellaneous methods
int SCIPrandomGetInt(SCIP_RANDNUMGEN *randnumgen, int minrandval, int maxrandval)
Definition: misc.c:9959
#define DEFAULT_BESTSOLWEIGHT
Definition: heur_alns.c:105
#define DECL_NHEXIT(x)
Definition: heur_alns.c:272
int SCIPgetDepth(SCIP *scip)
Definition: scip_tree.c:638
#define SCIP_Bool
Definition: def.h:70
SCIP_Longint usednodes
Definition: heur_alns.c:324
SCIP_RETCODE SCIPhashmapCreate(SCIP_HASHMAP **hashmap, BMS_BLKMEM *blkmem, int mapsize)
Definition: misc.c:3014
static SCIP_RETCODE fixMatchingSolutionValues(SCIP *scip, SCIP_SOL **sols, int nsols, SCIP_VAR **vars, int nvars, SCIP_VAR **varbuf, SCIP_Real *valbuf, int *nfixings)
Definition: heur_alns.c:2757
SCIP_RETCODE SCIPsetHeurExit(SCIP *scip, SCIP_HEUR *heur, SCIP_DECL_HEUREXIT((*heurexit)))
Definition: scip_heur.c:201
enum SCIP_Status SCIP_STATUS
Definition: type_stat.h:58
static const char * paramname[]
Definition: lpi_msk.c:4974
#define DEFAULT_MAXFIXINGRATE_TRUSTREGION
Definition: heur_alns.c:187
#define DEFAULT_MAXFIXINGRATE_ZEROOBJECTIVE
Definition: heur_alns.c:177
SCIP_RETCODE SCIPcreateBanditUcb(SCIP *scip, SCIP_BANDIT **ucb, SCIP_Real *priorities, SCIP_Real alpha, int nactions, unsigned int initseed)
Definition: bandit_ucb.c:330
SCIP_EXPORT SCIP_Real SCIPvarGetUbGlobal(SCIP_VAR *var)
Definition: var.c:17677
public methods for statistics table plugins
SCIP_Bool SCIPisParamFixed(SCIP *scip, const char *name)
Definition: scip_param.c:210
static SCIP_Real getVariablePscostScore(SCIP *scip, SCIP_VAR *var, SCIP_Real refsolval)
Definition: heur_alns.c:1294
#define DEFAULT_ACTIVE_TRUSTREGION
Definition: heur_alns.c:188
static SCIP_RETCODE transferSolution(SCIP *subscip, SCIP_EVENTDATA *eventdata)
Definition: heur_alns.c:898
#define MAX(x, y)
Definition: tclique_def.h:83
SCIP_Bool SCIPisDualfeasPositive(SCIP *scip, SCIP_Real val)
static void initRunStats(SCIP *scip, NH_STATS *stats)
Definition: heur_alns.c:1008
SCIP_Real SCIPgetConfidenceBoundUcb(SCIP_BANDIT *ucb, int action)
Definition: bandit_ucb.c:255
SCIP_Bool active
Definition: heur_alns.c:358
#define DECL_CHANGESUBSCIP(x)
Definition: heur_alns.c:254
#define DEFAULT_MAXFIXINGRATE_PROXIMITY
Definition: heur_alns.c:167
static void tryAdd2variableBuffer(SCIP *scip, SCIP_VAR *var, SCIP_Real val, SCIP_VAR **varbuf, SCIP_Real *valbuf, int *nfixings, SCIP_Bool integer)
Definition: heur_alns.c:1322
public methods for bandit algorithms
#define DEFAULT_MINFIXINGRATE_CROSSOVER
Definition: heur_alns.c:171
SCIP_RETCODE SCIPprintStatistics(SCIP *scip, FILE *file)
#define DEFAULT_ADJUSTMINIMPROVE
Definition: heur_alns.c:99
#define BMScopyMemoryArray(ptr, source, num)
Definition: memory.h:126
SCIP_EXPORT void SCIPselectInd(int *indarray, SCIP_DECL_SORTINDCOMP((*indcomp)), void *dataptr, int k, int len)
static void decreaseFixingRate(NH_FIXINGRATE *fx)
Definition: heur_alns.c:544
SCIP_RETCODE SCIPchgVarLbGlobal(SCIP *scip, SCIP_VAR *var, SCIP_Real newbound)
Definition: scip_var.c:4936
static SCIP_RETCODE neighborhoodExit(SCIP *scip, NH *neighborhood)
Definition: heur_alns.c:880
#define DEFAULT_SCALEBYEFFORT
Definition: heur_alns.c:108
SCIP_RETCODE SCIPstopClock(SCIP *scip, SCIP_CLOCK *clck)
Definition: scip_timing.c:169
static SCIP_DECL_HEUREXEC(heurExecAlns)
Definition: heur_alns.c:2277
#define DEFAULT_EPS
Definition: heur_alns.c:121
#define DEFAULT_MINFIXINGRATE_ZEROOBJECTIVE
Definition: heur_alns.c:176
#define HEUR_DESC
Definition: heur_alns.c:68
Constraint handler for linear constraints in their most general form, .
#define DEFAULT_MINFIXINGRATE_LOCALBRANCHING
Definition: heur_alns.c:161
int SCIPbanditGetNActions(SCIP_BANDIT *bandit)
Definition: bandit.c:294
static SCIP_RETCODE neighborhoodGetRefsol(SCIP *scip, NH *neighborhood, SCIP_SOL **solptr)
Definition: heur_alns.c:1353
int npoolsols
Definition: heur_alns.c:386
#define BMSclearMemory(ptr)
Definition: memory.h:121
SCIP_Longint nsolsfound
Definition: heur_alns.c:329
SCIP_RETCODE SCIPfreeClock(SCIP *scip, SCIP_CLOCK **clck)
Definition: scip_timing.c:118
static SCIP_RETCODE determineLimits(SCIP *scip, SCIP_HEUR *heur, SOLVELIMITS *solvelimits, SCIP_Bool *runagain)
Definition: heur_alns.c:1918
SCIP_RETCODE SCIPincludeEventhdlrBasic(SCIP *scip, SCIP_EVENTHDLR **eventhdlrptr, const char *name, const char *desc, SCIP_DECL_EVENTEXEC((*eventexec)), SCIP_EVENTHDLRDATA *eventhdlrdata)
Definition: scip_event.c:95
SCIP_RETCODE SCIPaddRealParam(SCIP *scip, const char *name, const char *desc, SCIP_Real *valueptr, SCIP_Bool isadvanced, SCIP_Real defaultvalue, SCIP_Real minvalue, SCIP_Real maxvalue, SCIP_DECL_PARAMCHGD((*paramchgd)), SCIP_PARAMDATA *paramdata)
Definition: scip_param.c:130
void SCIPswapPointers(void **pointer1, void **pointer2)
Definition: misc.c:10232
#define DEFAULT_DOMOREFIXINGS
Definition: heur_alns.c:130
unsigned int usedistances
Definition: heur_alns.c:479
static SCIP_BANDIT * getBandit(SCIP_HEURDATA *heurdata)
Definition: heur_alns.c:1981
public methods for the LP relaxation, rows and columns
int nrunsbestsol
Definition: heur_alns.c:328
public methods for bandit algorithms
#define SCIP_REAL_MAX
Definition: def.h:164
#define EVENTHDLR_NAME
Definition: heur_alns.c:197
#define HEUR_MAXDEPTH
Definition: heur_alns.c:73
SCIP_EXPORT void SCIPselectDownInd(int *indarray, SCIP_DECL_SORTINDCOMP((*indcomp)), void *dataptr, int k, int len)
static SCIP_RETCODE resetFixingRate(SCIP *scip, NH_FIXINGRATE *fixingrate)
Definition: heur_alns.c:489
static SCIP_DECL_EVENTEXEC(eventExecAlns)
Definition: heur_alns.c:974
SCIP_Real SCIPfloor(SCIP *scip, SCIP_Real val)
SCIP_RETCODE SCIPsetLongintParam(SCIP *scip, const char *name, SCIP_Longint value)
Definition: scip_param.c:561
SCIP_RETCODE SCIPgetSolVals(SCIP *scip, SCIP_SOL *sol, int nvars, SCIP_VAR **vars, SCIP_Real *vals)
Definition: scip_sol.c:1390
public methods for branching rule plugins and branching
SCIP_VAR ** b
Definition: circlepacking.c:56
#define DEFAULT_PRIORITY_RENS
Definition: heur_alns.c:149
SCIP_Real SCIPgetProbabilityExp3(SCIP_BANDIT *exp3, int action)
Definition: bandit_exp3.c:354
SCIP_RETCODE SCIPchgVarUbGlobal(SCIP *scip, SCIP_VAR *var, SCIP_Real newbound)
Definition: scip_var.c:5023
#define DEFAULT_MINFIXINGRATE_MUTATION
Definition: heur_alns.c:156
public methods for managing events
#define SCIP_EVENTTYPE_BESTSOLFOUND
Definition: type_event.h:96
general public methods
#define DEFAULT_MAXFIXINGRATE_MUTATION
Definition: heur_alns.c:157
public methods for solutions
static void printNeighborhoodStatistics(SCIP *scip, SCIP_HEURDATA *heurdata, FILE *file)
Definition: heur_alns.c:1063
static SCIP_RETCODE selectNeighborhood(SCIP *scip, SCIP_HEURDATA *heurdata, int *neighborhoodidx)
Definition: heur_alns.c:1991
SCIP_RETCODE SCIPchgVarObj(SCIP *scip, SCIP_VAR *var, SCIP_Real newobj)
Definition: scip_var.c:4507
public methods for random numbers
SCIP_Real maxfixingrate
Definition: heur_alns.c:342
SCIP_SOL ** SCIPgetSols(SCIP *scip)
Definition: scip_sol.c:2255
SCIP_Real SCIPgetLowerbound(SCIP *scip)
#define DEFAULT_NPOOLSOLS_DINS
Definition: heur_alns.c:193
#define DEFAULT_PRIORITY_TRUSTREGION
Definition: heur_alns.c:189
SCIP_EXPORT SCIP_Real SCIPvarGetLbGlobal(SCIP_VAR *var)
Definition: var.c:17667
SCIP_RETCODE SCIPsetHeurCopy(SCIP *scip, SCIP_HEUR *heur, SCIP_DECL_HEURCOPY((*heurcopy)))
Definition: scip_heur.c:153
#define DEFAULT_COPYCUTS
Definition: heur_alns.c:137
SCIP_EXPORT SCIP_Longint SCIPsolGetNodenum(SCIP_SOL *sol)
Definition: sol.c:2584
#define DEFAULT_FIXTOL
Definition: heur_alns.c:112
static SCIP_RETCODE getReward(SCIP *scip, SCIP_HEURDATA *heurdata, NH_STATS *runstats, SCIP_Real *rewardptr)
Definition: heur_alns.c:2014
#define CROSSOVERSEED
Definition: heur_alns.c:143
static SCIP_RETCODE setLimits(SCIP *subscip, SOLVELIMITS *solvelimits)
Definition: heur_alns.c:1898
public methods for message output
SCIP_RETCODE SCIPgetVarsData(SCIP *scip, SCIP_VAR ***vars, int *nvars, int *nbinvars, int *nintvars, int *nimplvars, int *ncontvars)
Definition: scip_prob.c:1860
#define DEFAULT_NSOLS_CROSSOVER
Definition: heur_alns.c:192
SCIP_Real SCIPgetSolTransObj(SCIP *scip, SCIP_SOL *sol)
Definition: scip_sol.c:1483
int SCIPsnprintf(char *t, int len, const char *s,...)
Definition: misc.c:10604
SCIP_RETCODE SCIPaddIntParam(SCIP *scip, const char *name, const char *desc, int *valueptr, SCIP_Bool isadvanced, int defaultvalue, int minvalue, int maxvalue, SCIP_DECL_PARAMCHGD((*paramchgd)), SCIP_PARAMDATA *paramdata)
Definition: scip_param.c:74
SCIP_RETCODE SCIPaddTrustregionNeighborhoodConstraint(SCIP *sourcescip, SCIP *targetscip, SCIP_VAR **subvars, SCIP_Real violpenalty)
Definition: heuristics.c:990
void SCIPhashmapFree(SCIP_HASHMAP **hashmap)
Definition: misc.c:3048
int statushist[NHISTENTRIES]
Definition: heur_alns.c:332
SCIP_Real SCIPgetVarPseudocostVal(SCIP *scip, SCIP_VAR *var, SCIP_Real solvaldelta)
Definition: scip_var.c:8742
#define SCIP_Real
Definition: def.h:163
SCIP_Real SCIPretransformObj(SCIP *scip, SCIP_Real obj)
Definition: scip_sol.c:1568
#define DEFAULT_SEED
Definition: heur_alns.c:141
static int getHistIndex(SCIP_STATUS subscipstatus)
Definition: heur_alns.c:1037
public methods for message handling
SCIP_RETCODE SCIPstartClock(SCIP *scip, SCIP_CLOCK *clck)
Definition: scip_timing.c:152
public methods for Exp.3
SCIP_RETCODE SCIPsetHeurInitsol(SCIP *scip, SCIP_HEUR *heur, SCIP_DECL_HEURINITSOL((*heurinitsol)))
Definition: scip_heur.c:217
#define SCIP_Longint
Definition: def.h:148
SCIP_RETCODE SCIPsetBoolParam(SCIP *scip, const char *name, SCIP_Bool value)
Definition: scip_param.c:445
SCIP_Real minfixingrate
Definition: heur_alns.c:339
SCIP_RANDNUMGEN * rng
Definition: heur_alns.c:372
int SCIPgetNBinVars(SCIP *scip)
Definition: scip_prob.c:2031
SCIP_RETCODE SCIPsetHeurFree(SCIP *scip, SCIP_HEUR *heur, SCIP_DECL_HEURFREE((*heurfree)))
Definition: scip_heur.c:169
#define DEFAULT_PRIORITY_CROSSOVER
Definition: heur_alns.c:174
SCIP_RETCODE SCIPaddLongintParam(SCIP *scip, const char *name, const char *desc, SCIP_Longint *valueptr, SCIP_Bool isadvanced, SCIP_Longint defaultvalue, SCIP_Longint minvalue, SCIP_Longint maxvalue, SCIP_DECL_PARAMCHGD((*paramchgd)), SCIP_PARAMDATA *paramdata)
Definition: scip_param.c:102
SCIP_EXPORT int SCIPvarGetProbindex(SCIP_VAR *var)
Definition: var.c:17360
SCIP_RETCODE SCIPaddCons(SCIP *scip, SCIP_CONS *cons)
Definition: scip_prob.c:2764
#define DEFAULT_MAXFIXINGRATE_RINS
Definition: heur_alns.c:152
#define DEFAULT_ACTIVE_DINS
Definition: heur_alns.c:183
SCIP_Real * randscores
Definition: heur_alns.c:474
SCIP_Real SCIPfeasCeil(SCIP *scip, SCIP_Real val)
#define DEFAULT_MAXFIXINGRATE_CROSSOVER
Definition: heur_alns.c:172
#define NHISTENTRIES
Definition: heur_alns.c:316
#define BMSclearMemoryArray(ptr, num)
Definition: memory.h:122
public methods for primal heuristics
SCIP_RETCODE SCIPfree(SCIP **scip)
Definition: scip_general.c:315
#define DEFAULT_USELOCALREDCOST
Definition: heur_alns.c:114
SCIP_Longint SCIPgetMemExternEstim(SCIP *scip)
Definition: scip_mem.c:117
void SCIPinfoMessage(SCIP *scip, FILE *file, const char *formatstr,...)
Definition: scip_message.c:199
#define MINIMPROVEFAC
Definition: heur_alns.c:97
#define DEFAULT_TARGETNODEFACTOR
Definition: heur_alns.c:88
unsigned int usepscost
Definition: heur_alns.c:480
#define SCIP_CALL_ABORT(x)
Definition: def.h:349
SCIP_RETCODE SCIPreleaseCons(SCIP *scip, SCIP_CONS **cons)
Definition: scip_cons.c:1110
SCIP_Real * SCIPgetWeightsEpsgreedy(SCIP_BANDIT *epsgreedy)
static void computeIntegerVariableBoundsDins(SCIP *scip, SCIP_VAR *var, SCIP_Real *lbptr, SCIP_Real *ubptr)
Definition: heur_alns.c:3290
#define MUTATIONSEED
Definition: heur_alns.c:142
#define DEFAULT_BETA
Definition: heur_alns.c:115
#define TABLE_NAME_NEIGHBORHOOD
Definition: heur_alns.c:202
SCIP_RETCODE SCIPtrySolFree(SCIP *scip, SCIP_SOL **sol, SCIP_Bool printreason, SCIP_Bool completely, SCIP_Bool checkbounds, SCIP_Bool checkintegrality, SCIP_Bool checklprows, SCIP_Bool *stored)
Definition: scip_sol.c:3232
#define SCIP_ALLOC(x)
Definition: def.h:381
#define SCIPABORT()
Definition: def.h:342
public methods for global and local (sub)problems
SCIP_EXPORT SCIP_Real SCIPvarGetBestRootRedcost(SCIP_VAR *var)
Definition: var.c:13549
static SCIP_RETCODE neighborhoodChangeSubscip(SCIP *sourcescip, SCIP *targetscip, NH *neighborhood, SCIP_VAR **targetvars, int *ndomchgs, int *nchgobjs, int *naddedconss, SCIP_Bool *success)
Definition: heur_alns.c:1858
#define TABLE_EARLIEST_STAGE_NEIGHBORHOOD
Definition: heur_alns.c:205
static SCIP_RETCODE setupSubScip(SCIP *scip, SCIP *subscip, SCIP_VAR **subvars, SOLVELIMITS *solvelimits, SCIP_HEUR *heur, SCIP_Bool objchgd)
Definition: heur_alns.c:2115
#define DEFAULT_REWARDCONTROL
Definition: heur_alns.c:107
SCIP_RETCODE SCIPaddCharParam(SCIP *scip, const char *name, const char *desc, char *valueptr, SCIP_Bool isadvanced, char defaultvalue, const char *allowedvalues, SCIP_DECL_PARAMCHGD((*paramchgd)), SCIP_PARAMDATA *paramdata)
Definition: scip_param.c:158
SCIP_SOL * SCIPgetBestSol(SCIP *scip)
Definition: scip_sol.c:2305
SCIP_RETCODE SCIPsetIntParam(SCIP *scip, const char *name, int value)
Definition: scip_param.c:503
SCIP_RETCODE SCIPcheckSol(SCIP *scip, SCIP_SOL *sol, SCIP_Bool printreason, SCIP_Bool completely, SCIP_Bool checkbounds, SCIP_Bool checkintegrality, SCIP_Bool checklprows, SCIP_Bool *feasible)
Definition: scip_sol.c:3441
SCIP_RETCODE SCIPsetSeparating(SCIP *scip, SCIP_PARAMSETTING paramsetting, SCIP_Bool quiet)
Definition: scip_param.c:974
public methods for UCB bandit selection
static void increaseMinimumImprovement(SCIP_HEURDATA *heurdata)
Definition: heur_alns.c:668
#define FIXINGRATE_STARTINC
Definition: heur_alns.c:135
int * distances
Definition: heur_alns.c:475
static void resetTargetNodeLimit(SCIP_HEURDATA *heurdata)
Definition: heur_alns.c:612
methods for selecting (weighted) k-medians
SCIP_Bool SCIPisFeasPositive(SCIP *scip, SCIP_Real val)
#define DEFAULT_ACTIVE_MUTATION
Definition: heur_alns.c:158
#define HEUR_PRIORITY
Definition: heur_alns.c:70
memory allocation routines
static SCIP_RETCODE includeNeighborhoods(SCIP *scip, SCIP_HEURDATA *heurdata)
Definition: heur_alns.c:3582