Scippy

SCIP

Solving Constraint Integer Programs

heur_vbounds.c
Go to the documentation of this file.
1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
2 /* */
3 /* This file is part of the program and library */
4 /* SCIP --- Solving Constraint Integer Programs */
5 /* */
6 /* Copyright (c) 2002-2024 Zuse Institute Berlin (ZIB) */
7 /* */
8 /* Licensed under the Apache License, Version 2.0 (the "License"); */
9 /* you may not use this file except in compliance with the License. */
10 /* You may obtain a copy of the License at */
11 /* */
12 /* http://www.apache.org/licenses/LICENSE-2.0 */
13 /* */
14 /* Unless required by applicable law or agreed to in writing, software */
15 /* distributed under the License is distributed on an "AS IS" BASIS, */
16 /* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. */
17 /* See the License for the specific language governing permissions and */
18 /* limitations under the License. */
19 /* */
20 /* You should have received a copy of the Apache-2.0 license */
21 /* along with SCIP; see the file LICENSE. If not visit scipopt.org. */
22 /* */
23 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
24 
25 /**@file heur_vbounds.c
26  * @ingroup DEFPLUGINS_HEUR
27  * @brief LNS heuristic uses the variable lower and upper bounds to determine the search neighborhood
28  * @author Timo Berthold
29  * @author Stefan Heinz
30  * @author Jens Schulz
31  * @author Gerald Gamrath
32  *
33  * @todo allow smaller fixing rate for probing LP?
34  * @todo allow smaller fixing rate after presolve if total number of variables is small (<= 1000)?
35  *
36  * More details about the heuristic can be found in@n
37  * Structure-Based Primal Heuristics for Mixed Integer Programming@n
38  * Gerald Gamrath, Timo Berthold, Stefan Heinz, and Michael Winkler@n
39  * Optimization in the Real World, Volume 13 of the series Mathematics for Industry, pp 37-53@n
40  * Preliminary version available as <a href="https://opus4.kobv.de/opus4-zib/frontdoor/index/index/docId/5551">ZIB-Report 15-26</a>.
41  */
42 
43 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
44 
45 #include "blockmemshell/memory.h"
46 #include "scip/heur_locks.h"
47 #include "scip/heur_vbounds.h"
48 #include "scip/pub_heur.h"
49 #include "scip/pub_implics.h"
50 #include "scip/pub_message.h"
51 #include "scip/pub_misc.h"
52 #include "scip/pub_tree.h"
53 #include "scip/pub_var.h"
54 #include "scip/scip_branch.h"
55 #include "scip/scip_cons.h"
56 #include "scip/scip_copy.h"
57 #include "scip/scip_general.h"
58 #include "scip/scip_heur.h"
59 #include "scip/scip_lp.h"
60 #include "scip/scip_mem.h"
61 #include "scip/scip_message.h"
62 #include "scip/scip_numerics.h"
63 #include "scip/scip_param.h"
64 #include "scip/scip_prob.h"
65 #include "scip/scip_probing.h"
66 #include "scip/scip_sol.h"
67 #include "scip/scip_solve.h"
68 #include "scip/scip_solvingstats.h"
69 #include "scip/scip_timing.h"
70 #include "scip/scip_tree.h"
71 #include "scip/scip_var.h"
72 #include <string.h>
73 
74 #ifdef SCIP_STATISTIC
75 #include "scip/clock.h"
76 #endif
77 
78 #define VBOUNDVARIANT_NOOBJ 0x001u
79 #define VBOUNDVARIANT_BESTBOUND 0x002u
80 #define VBOUNDVARIANT_WORSTBOUND 0x004u
81 
82 #define HEUR_NAME "vbounds"
83 #define HEUR_DESC "LNS heuristic uses the variable lower and upper bounds to determine the search neighborhood"
84 #define HEUR_DISPCHAR SCIP_HEURDISPCHAR_PROP
85 #define HEUR_PRIORITY 2500
86 #define HEUR_FREQ 0
87 #define HEUR_FREQOFS 0
88 #define HEUR_MAXDEPTH -1
89 #define HEUR_TIMING SCIP_HEURTIMING_BEFORENODE
90 #define HEUR_USESSUBSCIP TRUE /**< does the heuristic use a secondary SCIP instance? */
91 
92 #define DEFAULT_MAXNODES 5000LL /**< maximum number of nodes to regard in the subproblem */
93 #define DEFAULT_MININTFIXINGRATE 0.65 /**< minimum percentage of integer variables that have to be fixed */
94 #define DEFAULT_MINMIPFIXINGRATE 0.65 /**< minimuskipobjm percentage of variables that have to be fixed within sub-SCIP
95  * (integer and continuous) */
96 #define DEFAULT_MINIMPROVE 0.01 /**< factor by which vbounds heuristic should at least improve the
97  * incumbent */
98 #define DEFAULT_MINNODES 500LL /**< minimum number of nodes to regard in the subproblem */
99 #define DEFAULT_NODESOFS 500LL /**< number of nodes added to the contingent of the total nodes */
100 #define DEFAULT_NODESQUOT 0.1 /**< subproblem nodes in relation to nodes of the original problem */
101 #define DEFAULT_MAXPROPROUNDS 2 /**< maximum number of propagation rounds during probing */
102 #define DEFAULT_MAXBACKTRACKS 10 /**< maximum number of backtracks during the fixing process */
103 #define DEFAULT_COPYCUTS TRUE /**< should all active cuts from the cutpool of the original scip be copied to
104  * constraints of the subscip? */
105 #define DEFAULT_USELOCKFIXINGS FALSE /**< should more variables be fixed based on variable locks if
106  * the fixing rate was not reached?
107  */
109 /** which variants of the vbounds heuristic that try to stay feasible should be called? */
110 #define DEFAULT_FEASVARIANT (VBOUNDVARIANT_BESTBOUND | VBOUNDVARIANT_WORSTBOUND)
111 
112 /** which tightening variants of the vbounds heuristic should be called? */
113 #define DEFAULT_TIGHTENVARIANT (VBOUNDVARIANT_NOOBJ | VBOUNDVARIANT_BESTBOUND | VBOUNDVARIANT_WORSTBOUND)
114 
116 /*
117  * Data structures
118  */
119 
120 /** primal heuristic data */
121 struct SCIP_HeurData
122 {
123  SCIP_VAR** vbvars; /**< topological sorted variables with respect to the variable bounds */
124  SCIP_BOUNDTYPE* vbbounds; /**< topological sorted variables with respect to the variable bounds */
125  int nvbvars; /**< number of variables in variable lower bound array */
126  SCIP_Longint maxnodes; /**< maximum number of nodes to regard in the subproblem */
127  SCIP_Longint minnodes; /**< minimum number of nodes to regard in the subproblem */
128  SCIP_Longint nodesofs; /**< number of nodes added to the contingent of the total nodes */
129  SCIP_Longint usednodes; /**< nodes already used by vbounds heuristic in earlier calls */
130  SCIP_Real minintfixingrate; /**< minimum percentage of integer variables that have to be fixed */
131  SCIP_Real minmipfixingrate; /**< minimum percentage of variables that have to be fixed within sub-SCIP
132  * (integer and continuous) */
133  SCIP_Real minimprove; /**< factor by which vbounds heuristic should at least improve the incumbent */
134  SCIP_Real nodesquot; /**< subproblem nodes in relation to nodes of the original problem */
135  SCIP_Real cutoffbound;
136  int maxproprounds; /**< maximum number of propagation rounds during probing */
137  int maxbacktracks; /**< maximum number of backtracks during the fixing process */
138  int feasvariant; /**< which variants of the vbounds heuristic that try to stay feasible
139  * should be called? */
140  int tightenvariant; /**< which tightening variants of the vbounds heuristic should be called? */
141  SCIP_Bool initialized; /**< is the candidate list initialized? */
142  SCIP_Bool applicable; /**< is the heuristic applicable? */
143  SCIP_Bool copycuts; /**< should all active cuts from cutpool be copied to constraints in
144  * subproblem? */
145  SCIP_Bool uselockfixings; /**< should more variables be fixed based on variable locks if
146  * the fixing rate was not reached? */
147 };
148 
149 /**@name Heuristic defines
150  *
151  * @{
152  *
153  * The heuristic works on indices representing a bound of a variable. This index will be called bound index in the
154  * following. For a given active variable with problem index i (note that active variables have problem indices
155  * between 0 and nactivevariable - 1), the bound index of its lower bound is 2*i, the bound index of its upper
156  * bound is 2*i + 1. The other way around, a given bound index i corresponds to the variable with problem index
157  * i/2 (rounded down), and to the lower bound, if i is even, to the upper bound if i is odd.
158  * The following macros can be used to convert bound index into variable problem index and boundtype and vice versa.
159  */
160 #define getLbIndex(idx) (2*(idx))
161 #define getUbIndex(idx) (2*(idx)+1)
162 #define getVarIndex(idx) ((idx)/2)
163 #define getBoundtype(idx) (((idx) % 2 == 0) ? SCIP_BOUNDTYPE_LOWER : SCIP_BOUNDTYPE_UPPER)
164 #define isIndexLowerbound(idx) ((idx) % 2 == 0)
165 #define getOtherBoundIndex(idx) (((idx) % 2 == 0) ? (idx) + 1 : (idx) - 1)
168 /*
169  * Local methods
170  */
171 
172 /** reset heuristic data structure */
173 static
174 void heurdataReset(
175  SCIP_HEURDATA* heurdata /**< structure containing heurdata */
176  )
177 {
178  heurdata->vbvars = NULL;
179  heurdata->vbbounds = NULL;
180  heurdata->nvbvars = 0;
181  heurdata->initialized = FALSE;
182  heurdata->applicable = FALSE;
183 }
184 
185 
186 /** performs depth-first-search in the implicitly given directed graph from the given start index */
187 static
189  SCIP* scip, /**< SCIP data structure */
190  int startnode, /**< node to start the depth-first-search */
191  SCIP_Shortbool* visited, /**< array to store for each node, whether it was already visited */
192  int* dfsstack, /**< array of size number of nodes to store the stack;
193  * only needed for performance reasons */
194  int* stacknextedge, /**< array of size number of nodes to store the number of adjacent nodes
195  * already visited for each node on the stack; only needed for
196  * performance reasons */
197  int* stacknextcliquevar, /**< array of size number of nodes to store the number of variables
198  * already evaluated for the clique currently being evaluated */
199  int* cliqueexit, /**< exit node when entering a clique */
200  int* dfsnodes, /**< array of nodes that can be reached starting at startnode, in reverse
201  * dfs order */
202  int* ndfsnodes /**< pointer to store number of nodes that can be reached starting at
203  * startnode */
204  )
205 {
206  SCIP_VAR** vars;
207  SCIP_VAR* startvar;
208  SCIP_VAR** vbvars;
209  SCIP_Real* coefs;
210  SCIP_Bool lower;
211  SCIP_Bool found;
212  int maxstacksize;
213  int stacksize;
214  int curridx;
215  int idx;
216  int nvbvars;
217  int i;
218 
219  assert(startnode >= 0);
220  assert(startnode < 2 * SCIPgetNVars(scip));
221  assert(visited != NULL);
222  assert(visited[startnode] == FALSE);
223  assert(dfsstack != NULL);
224  assert(dfsnodes != NULL);
225  assert(ndfsnodes != NULL);
226 
227  vars = SCIPgetVars(scip);
228 
229  /* put start node on the stack */
230  dfsstack[0] = startnode;
231  stacknextcliquevar[0] = 0;
232  stacknextedge[0] = 0;
233  maxstacksize = 1;
234  stacksize = 1;
235  idx = -1;
236 
237  /* we run until no more bounds indices are on the stack */
238  while( stacksize > 0 )
239  {
240  /* get next node from stack */
241  curridx = dfsstack[stacksize - 1];
242 
243  /* mark current node as visited */
244  assert(visited[curridx] == (stacknextedge[stacksize - 1] != 0));
245  visited[curridx] = TRUE;
246  found = FALSE;
247 
248  startvar = vars[getVarIndex(curridx)];
249  lower = isIndexLowerbound(curridx);
250 
251  if( stacknextedge[stacksize - 1] >= 0 )
252  {
253  /* go over edges corresponding to varbounds */
254  if( lower )
255  {
256  vbvars = SCIPvarGetVlbVars(startvar);
257  coefs = SCIPvarGetVlbCoefs(startvar);
258  nvbvars = SCIPvarGetNVlbs(startvar);
259  }
260  else
261  {
262  vbvars = SCIPvarGetVubVars(startvar);
263  coefs = SCIPvarGetVubCoefs(startvar);
264  nvbvars = SCIPvarGetNVubs(startvar);
265  }
266 
267  /* iterate over all vbounds for the given bound */
268  for( i = stacknextedge[stacksize - 1]; i < nvbvars; ++i )
269  {
270  if( !SCIPvarIsActive(vbvars[i]) )
271  continue;
272 
273  idx = (SCIPisPositive(scip, coefs[i]) == lower) ? getLbIndex(SCIPvarGetProbindex(vbvars[i])) : getUbIndex(SCIPvarGetProbindex(vbvars[i]));
274  assert(idx >= 0);
275 
276  /* break when the first unvisited node is reached */
277  if( !visited[idx] )
278  break;
279  }
280 
281  /* we stopped because we found an unhandled node and not because we reached the end of the list */
282  if( i < nvbvars )
283  {
284  assert(!visited[idx]);
285 
286  /* put the adjacent node onto the stack */
287  dfsstack[stacksize] = idx;
288  stacknextedge[stacksize] = 0;
289  stacknextcliquevar[stacksize] = 0;
290  stacknextedge[stacksize - 1] = i + 1;
291  stacksize++;
292  assert(stacksize <= 2* SCIPgetNVars(scip));
293 
294  /* restart while loop, get next index from stack */
295  continue;
296  }
297  }
298 
299  stacknextedge[stacksize - 1] = -1;
300 
301  /* treat cliques */
302  if( SCIPvarIsBinary(startvar) )
303  {
304  SCIP_CLIQUE** cliques = SCIPvarGetCliques(startvar, !lower);
305  int ncliques = SCIPvarGetNCliques(startvar, !lower);
306  int j;
307 
308  /* iterate over all not yet handled cliques and search for an unvisited node */
309  for( j = -stacknextedge[stacksize - 1] - 1; j < ncliques; ++j )
310  {
311  SCIP_VAR** cliquevars;
312  SCIP_Bool* cliquevals;
313  int ncliquevars;
314 
315  /* the first time we evaluate this clique for the current node */
316  if( stacknextcliquevar[stacksize - 1] == 0 )
317  {
318  if( cliqueexit[SCIPcliqueGetIndex(cliques[j])] > 0 )
319  {
320  if( !visited[cliqueexit[SCIPcliqueGetIndex(cliques[j])] - 1] &&
321  cliqueexit[SCIPcliqueGetIndex(cliques[j])] - 1 != curridx )
322  {
323  stacknextedge[stacksize - 1] = -j - 2;
324  stacknextcliquevar[stacksize - 1] = 0;
325  idx = cliqueexit[SCIPcliqueGetIndex(cliques[j])] - 1;
326  cliqueexit[SCIPcliqueGetIndex(cliques[j])] = -1;
327  found = TRUE;
328  }
329  else
330  continue;
331  }
332  else if( cliqueexit[SCIPcliqueGetIndex(cliques[j])] == 0 )
333  {
334  cliqueexit[SCIPcliqueGetIndex(cliques[j])] = getOtherBoundIndex(curridx) + 1;
335  }
336  else
337  continue;
338  }
339  if( !found )
340  {
341  cliquevars = SCIPcliqueGetVars(cliques[j]);
342  cliquevals = SCIPcliqueGetValues(cliques[j]);
343  ncliquevars = SCIPcliqueGetNVars(cliques[j]);
344 
345  for( i = 0; i < ncliquevars; ++i )
346  {
347  assert(SCIPvarIsActive(cliquevars[i]));
348 
349  if( cliquevars[i] == startvar )
350  continue;
351 
352  if( cliquevals[i] )
353  idx = getLbIndex(SCIPvarGetProbindex(cliquevars[i]));
354  else
355  idx = getUbIndex(SCIPvarGetProbindex(cliquevars[i]));
356 
357  assert(idx >= 0 && idx < 2 * SCIPgetNVars(scip));
358 
359  /* break when the first unvisited node is reached */
360  if( idx >= 0 && !visited[idx] )
361  {
362  if( i < ncliquevars - 1 )
363  {
364  stacknextedge[stacksize - 1] = -j - 1;
365  stacknextcliquevar[stacksize - 1] = i + 1;
366  }
367  else
368  {
369  stacknextedge[stacksize - 1] = -j - 2;
370  stacknextcliquevar[stacksize - 1] = 0;
371  }
372  found = TRUE;
373  break;
374  }
375  }
376  }
377  if( found )
378  {
379  assert(!visited[idx]);
380 
381  /* put the adjacent node onto the stack */
382  dfsstack[stacksize] = idx;
383  stacknextedge[stacksize] = 0;
384  stacknextcliquevar[stacksize] = 0;
385  stacksize++;
386  assert(stacksize <= 2* SCIPgetNVars(scip));
387 
388  break;
389  }
390  }
391  /* restart while loop, get next index from stack */
392  if( found )
393  continue;
394  }
395 
396  maxstacksize = MAX(maxstacksize, stacksize);
397 
398  /* the current node was completely handled, remove it from the stack */
399  stacksize--;
400 
401  if( (maxstacksize > 1) && SCIPvarGetType(startvar) != SCIP_VARTYPE_CONTINUOUS )
402  {
403  /* store node in the sorted nodes array */
404  dfsnodes[(*ndfsnodes)] = curridx;
405  (*ndfsnodes)++;
406  }
407  else
408  visited[curridx] = FALSE;
409  }
410 
411  return SCIP_OKAY;
412 }
413 
414 
415 /** sort the bounds of variables topologically */
416 static
418  SCIP* scip, /**< SCIP data structure */
419  int* vbvars, /**< array to store variable bounds in topological order */
420  int* nvbvars /**< pointer to store number of variable bounds in the graph */
421  )
422 {
423  int* dfsstack;
424  int* stacknextedge;
425  int* stacknextcliquevar;
426  int* cliqueexit;
427  SCIP_Shortbool* visited;
428  int nbounds;
429  int i;
430 
431  assert(scip != NULL);
432 
433  nbounds = 2 * SCIPgetNVars(scip);
434 
435  SCIP_CALL( SCIPallocBufferArray(scip, &dfsstack, nbounds) );
436  SCIP_CALL( SCIPallocBufferArray(scip, &stacknextedge, nbounds) );
437  SCIP_CALL( SCIPallocBufferArray(scip, &stacknextcliquevar, nbounds) );
438  SCIP_CALL( SCIPallocClearBufferArray(scip, &cliqueexit, SCIPgetNCliques(scip)) );
439  SCIP_CALL( SCIPallocClearBufferArray(scip, &visited, nbounds) );
440 
441  /* while there are unvisited nodes, run dfs on the inverse graph starting from one of these nodes; the dfs orders are
442  * stored in the topoorder array, later dfs calls are just appended after the stacks of previous dfs calls, which
443  * gives us a topological order
444  */
445  for( i = 0; i < nbounds; ++i )
446  {
447  if( !visited[i] )
448  {
449  SCIP_CALL( dfs(scip, i, visited, dfsstack, stacknextedge, stacknextcliquevar, cliqueexit, vbvars, nvbvars) );
450  }
451  }
452  assert(*nvbvars <= nbounds);
453 
454  SCIPfreeBufferArray(scip, &visited);
455  SCIPfreeBufferArray(scip, &cliqueexit);
456  SCIPfreeBufferArray(scip, &stacknextcliquevar);
457  SCIPfreeBufferArray(scip, &stacknextedge);
458  SCIPfreeBufferArray(scip, &dfsstack);
459 
460  return SCIP_OKAY;
461 }
462 
463 /** initialize candidate lists */
464 static
466  SCIP* scip, /**< original SCIP data structure */
467  SCIP_HEURDATA* heurdata /**< structure containing heurdata */
468  )
469 {
470  SCIP_VAR** vars;
471  int* vbs;
472  int nvars;
473  int nvbs;
474  int v;
475 
476  SCIPdebugMsg(scip, "initialize variable bound heuristic (%s)\n", SCIPgetProbName(scip));
477 
478  vars = SCIPgetVars(scip);
479  nvars = SCIPgetNIntVars(scip) + SCIPgetNBinVars(scip) + SCIPgetNImplVars(scip);
480  nvbs = 0;
481 
482  /* initialize data */
483  heurdata->usednodes = 0;
484  heurdata->initialized = TRUE;
485 
486  if( nvars == 0 )
487  return SCIP_OKAY;
488 
489  /* allocate memory for the arrays of the heurdata */
490  SCIP_CALL( SCIPallocBufferArray(scip, &vbs, 2 * nvars) );
491 
492  /* create the topological sorted variable array with respect to the variable bounds */
493  SCIP_CALL( topologicalSort(scip, vbs, &nvbs) );
494 
495  /* check if the candidate list contains enough candidates */
496  if( nvbs > 0 && nvbs >= 0.1 * heurdata->minintfixingrate * nvars )
497  {
498  SCIP_CALL( SCIPallocBlockMemoryArray(scip, &heurdata->vbvars, nvbs) );
499  SCIP_CALL( SCIPallocBlockMemoryArray(scip, &heurdata->vbbounds, nvbs) );
500 
501  /* capture variable candidate list */
502  for( v = 0; v < nvbs; ++v )
503  {
504  heurdata->vbvars[v] = vars[getVarIndex(vbs[v])];
505  heurdata->vbbounds[v] = getBoundtype(vbs[v]);
506  assert(SCIPvarIsIntegral(heurdata->vbvars[v]));
507 
508  SCIP_CALL( SCIPcaptureVar(scip, heurdata->vbvars[v]) );
509  }
510 
511  heurdata->nvbvars = nvbs;
512  heurdata->applicable = TRUE;
513  }
514 
515  /* free buffer arrays */
516  SCIPfreeBufferArray(scip, &vbs);
517 
518  SCIPstatisticMessage("vbvars %.3g (%s)\n",
519  (nvbs * 100.0) / nvars, SCIPgetProbName(scip));
520 
521  /* if there is already a solution, add an objective cutoff */
522  if( SCIPgetNSols(scip) > 0 )
523  {
524  SCIP_Real upperbound;
525  SCIP_Real minimprove;
526  SCIP_Real cutoffbound;
527 
528  minimprove = heurdata->minimprove;
529  assert( !SCIPisInfinity(scip,SCIPgetUpperbound(scip)) );
530 
531  upperbound = SCIPgetUpperbound(scip) - SCIPsumepsilon(scip);
532 
533  if( !SCIPisInfinity(scip, -1.0 * SCIPgetLowerbound(scip)) )
534  {
535  cutoffbound = (1-minimprove) * SCIPgetUpperbound(scip) + minimprove * SCIPgetLowerbound(scip);
536  }
537  else
538  {
539  if( SCIPgetUpperbound ( scip ) >= 0 )
540  cutoffbound = (1 - minimprove) * SCIPgetUpperbound(scip);
541  else
542  cutoffbound = (1 + minimprove) * SCIPgetUpperbound(scip);
543  }
544  heurdata->cutoffbound = MIN(upperbound, cutoffbound);
545  }
546  else
547  heurdata->cutoffbound = SCIPinfinity(scip);
548  return SCIP_OKAY;
549 }
550 
551 /** apply variable bound fixing during probing */
552 static
554  SCIP* scip, /**< original SCIP data structure */
555  SCIP_HEURDATA* heurdata, /**< structure containing heurdata */
556  SCIP_VAR** vars, /**< variables to fix during probing */
557  int nvbvars, /**< number of variables in the variable bound graph */
558  SCIP_Bool tighten, /**< should variables be fixed to cause other fixings? */
559  int obj, /**< should the objective be taken into account? */
560  SCIP_Bool* allobj1, /**< pointer to store whether all variables were fixed according to obj=1 scheme */
561  SCIP_Bool* allobj2, /**< pointer to store whether all variables were fixed according to obj=2 scheme */
562  SCIP_Bool* backtracked, /**< was backtracking performed at least once? */
563  SCIP_Bool* infeasible /**< pointer to store whether propagation detected infeasibility */
564  )
565 {
566  SCIP_VAR* lastvar;
567  SCIP_VAR* var;
568  SCIP_Real lastfixval;
569  SCIP_Bool lastfixedlb;
570  SCIP_Bool fixtolower;
572  int nbacktracks = 0;
573  int v;
574 
575  /* loop over variables in topological order */
576  for( v = 0; v < nvbvars && !(*infeasible); ++v )
577  {
578  var = vars[v];
579  bound = heurdata->vbbounds[v];
580 
581  /*SCIPdebugMsg(scip, "topoorder[%d]: %s(%s) (%s) [%g,%g] (obj=%g)\n", v,
582  bound == SCIP_BOUNDTYPE_UPPER ? "ub" : "lb", SCIPvarGetName(var),
583  SCIPvarGetType(var) == SCIP_VARTYPE_CONTINUOUS ? "c" : "d",
584  SCIPvarGetLbLocal(var), SCIPvarGetUbLocal(var), SCIPvarGetObj(var));*/
585 
586  /* only check integer or binary variables */
588  continue;
589 
590  /* skip variables which are already fixed */
591  if( SCIPvarGetLbLocal(var) + 0.5 > SCIPvarGetUbLocal(var) )
592  continue;
593 
594  /* there are two cases for tighten:
595  * 1) tighten == TRUE: we go through the list of variables and fix variables to force propagation;
596  * this is be obtained by fixing the variable to the other bound (which means
597  * that the current bound is changed and so, much propagation is triggered
598  * since we are starting with the bounds which are most influential).
599  * 2) tighten == FALSE: we fix variables to avoid too much propagation in order to avoid reaching
600  * infeasibility. Therefore, we fix the variable to the current bound, so that
601  * this bound is not changed and does not propagate. The other bound is changed
602  * and propagates, but is later in the order, so less influential.
603  */
604  fixtolower = (tighten == (bound == SCIP_BOUNDTYPE_UPPER));
605 
606  /* if we want to take into account the objective function coefficients, we only perform a fixing if the variable
607  * would be fixed to its best bound; otherwise, we just continue
608  */
609  if( ((SCIPvarGetObj(var) >= 0) != fixtolower) )
610  {
611  if( obj == 1 )
612  continue;
613  else
614  *allobj1 = FALSE;
615  }
616  /* if we want to take into account the objective function coefficients but reverted, we only perform a fixing if the variable
617  * would be fixed to its worst bound; otherwise, we just continue
618  */
619  if( ((SCIPvarGetObj(var) >= 0) == fixtolower) )
620  {
621  if( obj == 2 )
622  continue;
623  else
624  *allobj2 = FALSE;
625  }
626  lastvar = var;
627 
628  /* fix the variable to its bound */
629  if( fixtolower )
630  {
631  /* we cannot fix to infinite bounds */
632  if( SCIPisInfinity(scip, -SCIPvarGetLbLocal(var)) )
633  continue;
634 
635  /* only open a new probing node if we will not exceed the maximal tree depth */
636  if( SCIP_MAXTREEDEPTH > SCIPgetDepth(scip) )
637  {
638  SCIP_CALL( SCIPnewProbingNode(scip) );
639  }
640 
641  /* fix variable to lower bound */
642  SCIP_CALL( SCIPfixVarProbing(scip, var, SCIPvarGetLbLocal(var)) );
643  SCIPdebugMsg(scip, "fixing %d: variable <%s> (obj=%g) to lower bound <%g> (%d pseudo cands)\n",
645  lastfixedlb = TRUE;
646  lastfixval = SCIPvarGetLbLocal(var);
647  }
648  else
649  {
650  /* we cannot fix to infinite bounds */
651  if( SCIPisInfinity(scip, SCIPvarGetUbLocal(var)) )
652  continue;
653 
654  /* only open a new probing node if we will not exceed the maximal tree depth */
655  if( SCIP_MAXTREEDEPTH > SCIPgetDepth(scip) )
656  {
657  SCIP_CALL( SCIPnewProbingNode(scip) );
658  }
659 
660  /* fix variable to upper bound */
661  SCIP_CALL( SCIPfixVarProbing(scip, var, SCIPvarGetUbLocal(var)) );
662  SCIPdebugMsg(scip, "fixing %d: variable <%s> (obj=%g) to upper bound <%g> (%d pseudo cands)\n",
664  lastfixedlb = FALSE;
665  lastfixval = SCIPvarGetUbLocal(var);
666  }
667 
668  /* check if problem is already infeasible */
669  SCIP_CALL( SCIPpropagateProbing(scip, heurdata->maxproprounds, infeasible, NULL) );
670 
671  /* probing detected infeasibility: backtrack */
672  if( *infeasible )
673  {
674  assert(lastvar != NULL);
675 
677  ++nbacktracks;
678  *infeasible = FALSE;
679 
680  /* increase the lower bound of the variable which caused the infeasibility */
681  if( lastfixedlb && lastfixval + 0.5 < SCIPvarGetUbLocal(lastvar) )
682  {
683  if( lastfixval + 0.5 > SCIPvarGetLbLocal(lastvar) )
684  {
685  SCIP_CALL( SCIPchgVarLbProbing(scip, lastvar, lastfixval + 1.0) );
686  }
687  }
688  else if( !lastfixedlb && lastfixval - 0.5 > SCIPvarGetLbLocal(lastvar) )
689  {
690  if( lastfixval - 0.5 < SCIPvarGetUbLocal(lastvar) )
691  {
692  SCIP_CALL( SCIPchgVarUbProbing(scip, lastvar, lastfixval - 1.0) );
693  }
694  }
695  /* because of the limited number of propagation rounds, it may happen that conflict analysis finds a valid
696  * global bound for the last fixed variable that conflicts with applying the reverse bound change after backtracking;
697  * in that case, we ran into a deadend and stop
698  */
699  else
700  {
701  *infeasible = TRUE;
702  }
703  lastvar = NULL;
704 
705  if( !(*infeasible) )
706  {
707  /* propagate fixings */
708  SCIP_CALL( SCIPpropagateProbing(scip, heurdata->maxproprounds, infeasible, NULL) );
709 
710  SCIPdebugMessage("backtrack %d was %sfeasible\n", nbacktracks, (*infeasible ? "in" : ""));
711  }
712 
713  if( *infeasible )
714  {
715  SCIPdebugMsg(scip, "probing was infeasible after %d backtracks\n", nbacktracks);
716 
717  break;
718  }
719  else if( nbacktracks > heurdata->maxbacktracks )
720  {
721  SCIPdebugMsg(scip, "interrupt probing after %d backtracks\n", nbacktracks);
722  break;
723  }
724  }
725  }
726 
727  *backtracked = (nbacktracks > 0);
728 
729  return SCIP_OKAY;
730 }
731 
732 /** copy problem to sub-SCIP, solve it, and add solutions */
733 static
735  SCIP* scip, /**< original SCIP data structure */
736  SCIP* subscip, /**< SCIP structure of the subproblem */
737  SCIP_HEUR* heur, /**< heuristic */
738  SCIP_VAR** vars, /**< variables of the main SCIP */
739  int nvars, /**< number of variables of the main SCIP */
740  SCIP_Longint nstallnodes, /**< stalling node limit for the sub-SCIP */
741  SCIP_Real lowerbound, /**< lower bound of the main SCIP / current subproblem */
742  int* nprevars, /**< pointer to store the number of presolved variables */
743  SCIP_Bool* wasfeas, /**< pointer to store if a feasible solution was found */
744  SCIP_RESULT* result /**< pointer to store the result */
745  )
746 {
747  SCIP_HEURDATA* heurdata;
748  SCIP_VAR** subvars;
749  SCIP_HASHMAP* varmap;
750  int i;
751 
752  assert(scip != NULL);
753  assert(subscip != NULL);
754  assert(heur != NULL);
755 
756  heurdata = SCIPheurGetData(heur);
757  assert(heurdata != NULL);
758 
759  /* create the variable mapping hash map */
760  SCIP_CALL( SCIPhashmapCreate(&varmap, SCIPblkmem(subscip), nvars) );
761 
762  SCIP_CALL( SCIPcopyConsCompression(scip, subscip, varmap, NULL, "_vbounds", NULL, NULL, 0, FALSE, FALSE, FALSE,
763  TRUE, NULL) );
764 
765  if( heurdata->copycuts )
766  {
767  /* copies all active cuts from cutpool of sourcescip to linear constraints in targetscip */
768  SCIP_CALL( SCIPcopyCuts(scip, subscip, varmap, NULL, FALSE, NULL) );
769  }
770 
771  SCIP_CALL( SCIPallocBufferArray(scip, &subvars, nvars) );
772 
773  for( i = 0; i < nvars; i++ )
774  subvars[i] = (SCIP_VAR*) SCIPhashmapGetImage(varmap, vars[i]);
775 
776  /* free hash map */
777  SCIPhashmapFree(&varmap);
778 
779  /* do not abort subproblem on CTRL-C */
780  SCIP_CALL( SCIPsetBoolParam(subscip, "misc/catchctrlc", FALSE) );
781 
782 #ifdef SCIP_DEBUG
783  /* for debugging, enable full output */
784  SCIP_CALL( SCIPsetIntParam(subscip, "display/verblevel", 5) );
785  SCIP_CALL( SCIPsetIntParam(subscip, "display/freq", 100000000) );
786 #else
787  /* disable statistic timing inside sub SCIP and output to console */
788  SCIP_CALL( SCIPsetIntParam(subscip, "display/verblevel", 0) );
789  SCIP_CALL( SCIPsetBoolParam(subscip, "timing/statistictiming", FALSE) );
790 #endif
791 
792  /* set limits for the subproblem */
793  SCIP_CALL( SCIPcopyLimits(scip, subscip) );
794  SCIP_CALL( SCIPsetLongintParam(subscip, "limits/stallnodes", nstallnodes) );
795  SCIP_CALL( SCIPsetLongintParam(subscip, "limits/nodes", heurdata->maxnodes) );
796 
797  /* speed up sub-SCIP by not checking dual LP feasibility */
798  SCIP_CALL( SCIPsetBoolParam(subscip, "lp/checkdualfeas", FALSE) );
799 
800  /* forbid call of heuristics and separators solving sub-CIPs */
801  SCIP_CALL( SCIPsetSubscipsOff(subscip, TRUE) );
802 
803  /* disable cutting plane separation */
805 
806  /* disable expensive presolving */
808 
809  /* use inference branching */
810  if( SCIPfindBranchrule(subscip, "inference") != NULL && !SCIPisParamFixed(subscip, "branching/inference/priority") )
811  {
812  SCIP_CALL( SCIPsetIntParam(subscip, "branching/inference/priority", INT_MAX/4) );
813  }
814 
815  /* set a cutoff bound */
816  if( SCIPgetNSols(scip) > 0 )
817  {
818  SCIP_Real upperbound;
819  SCIP_Real minimprove;
820  SCIP_Real cutoffbound;
821 
822  minimprove = heurdata->minimprove;
823  assert( !SCIPisInfinity(scip,SCIPgetUpperbound(scip)) );
824 
825  upperbound = SCIPgetUpperbound(scip) - SCIPsumepsilon(scip);
826 
827  if( !SCIPisInfinity(scip, -1.0 * lowerbound) )
828  {
829  cutoffbound = (1-minimprove) * SCIPgetUpperbound(scip) + minimprove * lowerbound;
830  }
831  else
832  {
833  if( SCIPgetUpperbound ( scip ) >= 0 )
834  cutoffbound = (1 - minimprove) * SCIPgetUpperbound(scip);
835  else
836  cutoffbound = (1 + minimprove) * SCIPgetUpperbound(scip);
837  }
838  heurdata->cutoffbound = MIN(upperbound, cutoffbound);
839  }
840 
841  if( !SCIPisInfinity(scip, heurdata->cutoffbound) )
842  {
843  SCIP_CALL( SCIPsetObjlimit(subscip, heurdata->cutoffbound) );
844  SCIPdebugMsg(scip, "setting objlimit for subscip to %g\n", heurdata->cutoffbound);
845  }
846 
847  SCIPdebugMsg(scip, "starting solving vbound-submip at time %g\n", SCIPgetSolvingTime(scip));
848 
849  /* solve the subproblem */
850  /* Errors in the LP solver should not kill the overall solving process, if the LP is just needed for a heuristic.
851  * Hence in optimized mode, the return code is caught and a warning is printed, only in debug mode, SCIP will stop.
852  */
853  SCIP_CALL_ABORT( SCIPpresolve(subscip) );
854 
855  SCIPdebugMsg(scip, "vbounds heuristic presolved subproblem at time %g : %d vars, %d cons; fixing value = %g\n",
856  SCIPgetSolvingTime(scip), SCIPgetNVars(subscip), SCIPgetNConss(subscip),
857  ((nvars - SCIPgetNVars(subscip)) / (SCIP_Real)nvars));
858 
859  *nprevars = SCIPgetNVars(subscip);
860 
861  /* after presolving, we should have at least reached a certain fixing rate over ALL variables (including continuous)
862  * to ensure that not only the MIP but also the LP relaxation is easy enough
863  */
864  if( ((nvars - SCIPgetNVars(subscip)) / (SCIP_Real)nvars) >= heurdata->minmipfixingrate )
865  {
866  SCIPdebugMsg(scip, "solving subproblem: nstallnodes=%" SCIP_LONGINT_FORMAT ", maxnodes=%" SCIP_LONGINT_FORMAT "\n", nstallnodes, heurdata->maxnodes);
867 
868  SCIP_CALL_ABORT( SCIPsolve(subscip) );
869 
870  SCIPdebugMsg(scip, "ending solving vbounds-submip at time %g, status = %d\n", SCIPgetSolvingTime(scip), SCIPgetStatus(subscip));
871 
872  /* check, whether a solution was found; due to numerics, it might happen that not all solutions are feasible ->
873  * try all solutions until one was accepted
874  */
875  SCIP_CALL( SCIPtranslateSubSols(scip, subscip, heur, subvars, wasfeas, NULL) );
876  if( (*wasfeas) )
877  {
878  SCIPdebugMsg(scip, "found feasible solution in sub-MIP\n");
879  *result = SCIP_FOUNDSOL;
880  }
881  }
882 
883 #ifdef SCIP_DEBUG
884  SCIP_CALL( SCIPprintStatistics(subscip, NULL) );
885 #endif
886 
887  /* free subproblem */
888  SCIPfreeBufferArray(scip, &subvars);
889 
890  return SCIP_OKAY;
891 }
892 
893 /** main procedure of the vbounds heuristic */
894 static
896  SCIP* scip, /**< original SCIP data structure */
897  SCIP_HEUR* heur, /**< heuristic */
898  SCIP_HEURDATA* heurdata, /**< heuristic data structure */
899  SCIP_VAR** vbvars, /**< variables to fix during probing */
900  int nvbvars, /**< number of variables to fix */
901  SCIP_Bool tighten, /**< should variables be fixed to cause other fixings? */
902  int obj, /**< should the objective be taken into account? */
903  SCIP_Bool* skipobj1, /**< pointer to store whether the run with obj=1 can be skipped, or NULL */
904  SCIP_Bool* skipobj2, /**< pointer to store whether the run with obj=2 can be skipped, or NULL */
905  SCIP_RESULT* result /**< pointer to store the result */
906  )
907 {
908  SCIPstatistic( SCIP_CLOCK* clock; )
909  SCIP_VAR** vars;
910  SCIP_Longint nstallnodes;
911  SCIP_LPSOLSTAT lpstatus;
912  SCIP_Real lowerbound;
913  SCIP_Bool wasfeas = FALSE;
914  SCIP_Bool cutoff;
915  SCIP_Bool lperror;
916  SCIP_Bool solvelp;
917  SCIP_Bool allobj1 = TRUE;
918  SCIP_Bool allobj2 = TRUE;
919  SCIP_Bool backtracked = TRUE;
920  int oldnpscands;
921  int npscands;
922  int nvars;
923  int nprevars;
924 
925  assert(heur != NULL);
926  assert(heurdata != NULL);
927  assert(nvbvars > 0);
928 
929  /* initialize default values */
930  cutoff = FALSE;
931 
932  if( skipobj1 != NULL )
933  *skipobj1 = FALSE;
934  if( skipobj2 != NULL )
935  *skipobj2 = FALSE;
936 
937  if( nvbvars < SCIPgetNVars(scip) * heurdata->minintfixingrate )
938  return SCIP_OKAY;
939 
940  if( *result == SCIP_DIDNOTRUN )
941  *result = SCIP_DIDNOTFIND;
942 
943  lowerbound = SCIPgetLowerbound(scip);
944 
945  oldnpscands = SCIPgetNPseudoBranchCands(scip);
946 
947  /* calculate the maximal number of branching nodes until heuristic is aborted */
948  nstallnodes = (SCIP_Longint)(heurdata->nodesquot * SCIPgetNNodes(scip));
949 
950  /* reward variable bounds heuristic if it succeeded often */
951  nstallnodes = (SCIP_Longint)(nstallnodes * 3.0 * (SCIPheurGetNBestSolsFound(heur)+1.0)/(SCIPheurGetNCalls(heur) + 1.0));
952  nstallnodes -= 100 * SCIPheurGetNCalls(heur); /* count the setup costs for the sub-MIP as 100 nodes */
953  nstallnodes += heurdata->nodesofs;
954 
955  /* determine the node limit for the current process */
956  nstallnodes -= heurdata->usednodes;
957  nstallnodes = MIN(nstallnodes, heurdata->maxnodes);
958 
959  SCIPdebugMsg(scip, "apply variable bounds heuristic at node %lld on %d variable bounds, tighten: %u obj: %d\n",
960  SCIPnodeGetNumber(SCIPgetCurrentNode(scip)), nvbvars, tighten, obj);
961 
962  /* check whether we have enough nodes left to call subproblem solving */
963  if( nstallnodes < heurdata->minnodes )
964  {
965  SCIPdebugMsg(scip, "skipping " HEUR_NAME ": nstallnodes=%" SCIP_LONGINT_FORMAT ", minnodes=%" SCIP_LONGINT_FORMAT "\n", nstallnodes, heurdata->minnodes);
966  return SCIP_OKAY;
967  }
968 
969  if( SCIPisStopped(scip) )
970  return SCIP_OKAY;
971 
972  SCIPstatistic( SCIP_CALL( SCIPcreateClock(scip, &clock) ) );
973  SCIPstatistic( SCIP_CALL( SCIPstartClock(scip, clock) ) );
974 
975  /* check whether the LP should be solved at the current node in the tree to determine whether the heuristic
976  * is allowed to solve an LP
977  */
978  solvelp = SCIPhasCurrentNodeLP(scip);
979 
980  if( !SCIPisLPConstructed(scip) && solvelp )
981  {
982  SCIP_CALL( SCIPconstructLP(scip, &cutoff) );
983 
984  /* manually cut off the node if the LP construction detected infeasibility (heuristics cannot return such a result) */
985  if( cutoff )
986  {
988  goto TERMINATE;
989  }
990 
991  SCIP_CALL( SCIPflushLP(scip) );
992  }
993 
994  /* get variable data of original problem */
995  SCIP_CALL( SCIPgetVarsData(scip, &vars, &nvars, NULL, NULL, NULL, NULL) );
996 
997  SCIPstatistic( nprevars = nvars; )
998 
999  /* start probing */
1000  SCIP_CALL( SCIPstartProbing(scip) );
1001 
1002 #ifdef COLLECTSTATISTICS
1003  SCIPenableVarHistory(scip);
1004 #endif
1005 
1006  /* apply the variable fixings */
1007  SCIP_CALL( applyVboundsFixings(scip, heurdata, vbvars, nvbvars, tighten, obj, &allobj1, &allobj2, &backtracked, &cutoff) );
1008 
1009  if( skipobj1 != NULL )
1010  *skipobj1 = allobj1;
1011 
1012  if( skipobj2 != NULL )
1013  *skipobj2 = allobj2;
1014 
1015  if( cutoff || SCIPisStopped(scip) )
1016  goto TERMINATE;
1017 
1018  /* check that we had enough fixings */
1019  npscands = SCIPgetNPseudoBranchCands(scip);
1020 
1021  SCIPdebugMsg(scip, "npscands=%d, oldnpscands=%d, heurdata->minintfixingrate=%g\n", npscands, oldnpscands, heurdata->minintfixingrate);
1022 
1023  /* check fixing rate */
1024  if( npscands > oldnpscands * (1.0 - heurdata->minintfixingrate) )
1025  {
1026  if( heurdata->uselockfixings && npscands <= 2.0 * oldnpscands * (1.0 - heurdata->minintfixingrate) )
1027  {
1028  SCIP_Bool allrowsfulfilled = FALSE;
1029 
1030  SCIP_CALL( SCIPapplyLockFixings(scip, NULL, &cutoff, &allrowsfulfilled) );
1031 
1032  if( cutoff || SCIPisStopped(scip) )
1033  {
1034  SCIPdebugMsg(scip, "cutoff or timeout in locks fixing\n");
1035  goto TERMINATE;
1036  }
1037 
1038  npscands = SCIPgetNPseudoBranchCands(scip);
1039 
1040  SCIPdebugMsg(scip, "after lockfixings: npscands=%d, oldnpscands=%d, allrowsfulfilled=%u, heurdata->minintfixingrate=%g\n",
1041  npscands, oldnpscands, allrowsfulfilled, heurdata->minintfixingrate);
1042 
1043  if( !allrowsfulfilled && npscands > oldnpscands * (1 - heurdata->minintfixingrate) )
1044  {
1045  SCIPdebugMsg(scip, "--> too few fixings\n");
1046 
1047  goto TERMINATE;
1048  }
1049  }
1050  else
1051  {
1052  SCIPdebugMsg(scip, "--> too few fixings\n");
1053 
1054  goto TERMINATE;
1055  }
1056  }
1057 
1058  assert(!cutoff);
1059 
1060  /*************************** Probing LP Solving ***************************/
1061  lpstatus = SCIP_LPSOLSTAT_ERROR;
1062  lperror = FALSE;
1063  /* solve lp only if the problem is still feasible */
1064  if( solvelp )
1065  {
1066  char strbuf[SCIP_MAXSTRLEN];
1067  int ncols;
1068 
1069  /* print message if relatively large LP is solved from scratch, since this could lead to a longer period during
1070  * which the user sees no output; more detailed probing stats only in debug mode */
1071  ncols = SCIPgetNLPCols(scip);
1072  if( !SCIPisLPSolBasic(scip) && ncols > 1000 )
1073  {
1074  int nunfixedcols = SCIPgetNUnfixedLPCols(scip);
1075 
1076  if( nunfixedcols > 0.5 * ncols )
1077  {
1079  "Heuristic " HEUR_NAME " solving LP from scratch with %.1f %% unfixed columns (%d of %d) ...\n",
1080  100.0 * (nunfixedcols / (SCIP_Real)ncols), nunfixedcols, ncols);
1081  }
1082  }
1083  SCIPdebugMsg(scip, "Heuristic " HEUR_NAME " probing LP: %s\n",
1084  SCIPsnprintfProbingStats(scip, strbuf, SCIP_MAXSTRLEN));
1085 
1086  /* solve LP; errors in the LP solver should not kill the overall solving process, if the LP is just needed for a
1087  * heuristic. hence in optimized mode, the return code is caught and a warning is printed, only in debug mode,
1088  * SCIP will stop.
1089  */
1090  SCIPdebugMsg(scip, "starting solving vbound-lp at time %g\n", SCIPgetSolvingTime(scip));
1091 #ifdef NDEBUG
1092  {
1093  SCIP_Bool retstat;
1094  retstat = SCIPsolveProbingLP(scip, -1, &lperror, NULL);
1095  if( retstat != SCIP_OKAY )
1096  {
1097  SCIPwarningMessage(scip, "Error while solving LP in vbound heuristic; LP solve terminated with code <%d>\n",
1098  retstat);
1099  }
1100  }
1101 #else
1102  SCIP_CALL( SCIPsolveProbingLP(scip, -1, &lperror, NULL) );
1103 #endif
1104  SCIPdebugMsg(scip, "ending solving vbound-lp at time %g\n", SCIPgetSolvingTime(scip));
1105 
1106  lpstatus = SCIPgetLPSolstat(scip);
1107 
1108  SCIPdebugMsg(scip, " -> new LP iterations: %" SCIP_LONGINT_FORMAT "\n", SCIPgetNLPIterations(scip));
1109  SCIPdebugMsg(scip, " -> error=%u, status=%d\n", lperror, lpstatus);
1110  }
1111 
1112  /* check if this is a feasible solution */
1113  if( lpstatus == SCIP_LPSOLSTAT_OPTIMAL && !lperror )
1114  {
1115  SCIP_Bool stored;
1116  SCIP_Bool success;
1117  SCIP_SOL* sol;
1118 
1119  lowerbound = SCIPgetLPObjval(scip);
1120 
1121  /* copy the current LP solution to the working solution */
1122  SCIP_CALL( SCIPcreateSol(scip, &sol, heur) );
1123  SCIP_CALL( SCIPlinkLPSol(scip, sol) );
1124 
1125  SCIP_CALL( SCIProundSol(scip, sol, &success) );
1126 
1127  if( success )
1128  {
1129  SCIPdebugMsg(scip, "vbound heuristic found roundable primal solution: obj=%g\n",
1130  SCIPgetSolOrigObj(scip, sol));
1131 
1132  /* check solution for feasibility, and add it to solution store if possible.
1133  * Neither integrality nor feasibility of LP rows have to be checked, because they
1134  * are guaranteed by the heuristic at this stage.
1135  */
1136 #ifdef SCIP_DEBUG
1137  SCIP_CALL( SCIPtrySol(scip, sol, TRUE, TRUE, TRUE, TRUE, TRUE, &stored) );
1138 #else
1139  SCIP_CALL( SCIPtrySol(scip, sol, FALSE, FALSE, TRUE, FALSE, FALSE, &stored) );
1140 #endif
1141 
1142 #ifdef SCIP_DEBUG
1143  SCIP_CALL( SCIPcheckSol(scip, sol, FALSE, FALSE, TRUE, TRUE, TRUE, &wasfeas) );
1144  assert(wasfeas);
1145  SCIPdebugMsg(scip, "found feasible solution by LP rounding: %16.9g\n", SCIPgetSolOrigObj(scip, sol));
1146 #endif
1147 
1148  if( stored )
1149  *result = SCIP_FOUNDSOL;
1150 
1151  SCIP_CALL( SCIPfreeSol(scip, &sol) );
1152 
1153  /* we found a solution, so we are done */
1154  goto TERMINATE;
1155  }
1156 
1157  SCIP_CALL( SCIPfreeSol(scip, &sol) );
1158  }
1159  /*************************** END Probing LP Solving ***************************/
1160 
1161  /*************************** Start Subscip Solving ***************************/
1162  /* if no solution has been found --> fix all other variables by subscip if necessary */
1163  if( !lperror && lpstatus != SCIP_LPSOLSTAT_INFEASIBLE && lpstatus != SCIP_LPSOLSTAT_OBJLIMIT )
1164  {
1165  SCIP* subscip;
1166  SCIP_RETCODE retcode;
1167  SCIP_Bool valid;
1168 
1169  /* check whether there is enough time and memory left */
1170  SCIP_CALL( SCIPcheckCopyLimits(scip, &valid) );
1171 
1172  if( !valid )
1173  goto TERMINATE;
1174 
1175  /* create subproblem */
1176  SCIP_CALL( SCIPcreate(&subscip) );
1177 
1178  retcode = setupAndSolveSubscip(scip, subscip, heur, vars, nvars, nstallnodes, lowerbound,
1179  &nprevars, &wasfeas, result);
1180 
1181  SCIP_CALL( SCIPfree(&subscip) );
1182 
1183  SCIP_CALL( retcode );
1184  }
1185 
1186  /*************************** End Subscip Solving ***************************/
1187 
1188  TERMINATE:
1189 #ifdef SCIP_STATISTIC
1190  SCIP_CALL( SCIPstopClock(scip, clock) );
1191  SCIPstatisticMessage("vbound: tighten=%u obj=%d nvars=%d presolnvars=%d ratio=%.2f infeas=%u found=%d time=%.4f\n",
1192  tighten, obj, nvars, nprevars, (nvars - nprevars) / (SCIP_Real)nvars, cutoff,
1193  wasfeas ? 1 : 0, SCIPclockGetTime(clock) );
1194 #endif
1195 
1196  SCIPstatistic( SCIP_CALL( SCIPfreeClock(scip, &clock) ) );
1197 
1198  /* exit probing mode */
1199  if( SCIPinProbing(scip) )
1200  {
1201  SCIP_CALL( SCIPendProbing(scip) );
1202  }
1203 
1204  return SCIP_OKAY; /*lint !e438*/
1205 }
1206 
1207 
1208 /*
1209  * Callback methods of primal heuristic
1210  */
1211 
1212 /** copy method for primal heuristic plugins (called when SCIP copies plugins) */
1213 static
1214 SCIP_DECL_HEURCOPY(heurCopyVbounds)
1215 { /*lint --e{715}*/
1216  assert(scip != NULL);
1217  assert(heur != NULL);
1218  assert(strcmp(SCIPheurGetName(heur), HEUR_NAME) == 0);
1220  /* call inclusion method of heuristic */
1222 
1223  return SCIP_OKAY;
1224 }
1225 
1226 /** destructor of primal heuristic to free user data (called when SCIP is exiting) */
1227 static
1228 SCIP_DECL_HEURFREE(heurFreeVbounds)
1229 { /*lint --e{715}*/
1230  SCIP_HEURDATA* heurdata;
1231 
1232  /* free heuristic data */
1233  heurdata = SCIPheurGetData(heur);
1234 
1235  SCIPfreeBlockMemory(scip, &heurdata);
1236  SCIPheurSetData(heur, NULL);
1237 
1238  return SCIP_OKAY;
1239 }
1240 
1241 
1242 /** solving process deinitialization method of primal heuristic (called before branch and bound process data is freed) */
1243 static
1244 SCIP_DECL_HEUREXITSOL(heurExitsolVbounds)
1245 { /*lint --e{715}*/
1246  SCIP_HEURDATA* heurdata;
1247  int v;
1248 
1249  heurdata = SCIPheurGetData(heur);
1250  assert(heurdata != NULL);
1251 
1252  /* release all variables */
1253  for( v = 0; v < heurdata->nvbvars; ++v )
1254  {
1255  SCIP_CALL( SCIPreleaseVar(scip, &heurdata->vbvars[v]) );
1256  }
1257 
1258  /* free varbounds array */
1259  SCIPfreeBlockMemoryArrayNull(scip, &heurdata->vbbounds, heurdata->nvbvars);
1260  SCIPfreeBlockMemoryArrayNull(scip, &heurdata->vbvars, heurdata->nvbvars);
1261 
1262  /* reset heuristic data structure */
1263  heurdataReset(heurdata);
1264 
1265  return SCIP_OKAY;
1266 }
1267 
1268 /** execution method of primal heuristic */
1269 static
1270 SCIP_DECL_HEUREXEC(heurExecVbounds)
1271 { /*lint --e{715}*/
1272  SCIP_HEURDATA* heurdata;
1273  SCIP_Bool skipobj1;
1274  SCIP_Bool skipobj2;
1275 #ifdef NOCONFLICT
1276  SCIP_Bool enabledconflicts;
1277 #endif
1278 
1279  assert( heur != NULL );
1280  assert( scip != NULL );
1281  assert( result != NULL );
1282 
1283  *result = SCIP_DIDNOTRUN;
1284 
1285  if( SCIPgetNPseudoBranchCands(scip) == 0 )
1286  return SCIP_OKAY;
1287 
1288  heurdata = SCIPheurGetData(heur);
1289  assert(heurdata != NULL);
1290 
1291  if( !heurdata->initialized )
1292  {
1293  SCIP_CALL( initializeCandsLists(scip, heurdata) );
1294  }
1295 
1296  if( !heurdata->applicable )
1297  return SCIP_OKAY;
1298 
1299 #ifdef NOCONFLICT
1300  /* disable conflict analysis */
1301  SCIP_CALL( SCIPgetBoolParam(scip, "conflict/enable", &enabledconflicts) );
1302 
1303  if( !SCIPisParamFixed(scip, "conflict/enable") )
1304  {
1305  SCIP_CALL( SCIPsetBoolParam(scip, "conflict/enable", FALSE) );
1306  }
1307 #endif
1308 
1309  /* try variable bounds */
1310  skipobj1 = FALSE;
1311  skipobj2 = FALSE;
1312  if( ((unsigned)heurdata->feasvariant & VBOUNDVARIANT_NOOBJ) != 0 )
1313  {
1314  SCIP_CALL( applyVbounds(scip, heur, heurdata, heurdata->vbvars, heurdata->nvbvars, FALSE, 0,
1315  &skipobj1, &skipobj2, result) );
1316  }
1317  if( !skipobj1 && ((unsigned) heurdata->feasvariant & VBOUNDVARIANT_BESTBOUND) != 0)
1318  {
1319  SCIP_CALL( applyVbounds(scip, heur, heurdata, heurdata->vbvars, heurdata->nvbvars, FALSE, 1, NULL, NULL, result) );
1320  }
1321  if( !skipobj2 && ((unsigned) heurdata->feasvariant & VBOUNDVARIANT_WORSTBOUND) != 0)
1322  {
1323  SCIP_CALL( applyVbounds(scip, heur, heurdata, heurdata->vbvars, heurdata->nvbvars, FALSE, 2, NULL, NULL, result) );
1324  }
1325 
1326  skipobj1 = FALSE;
1327  skipobj2 = FALSE;
1328  if( ((unsigned) heurdata->tightenvariant & VBOUNDVARIANT_NOOBJ) != 0 )
1329  {
1330  SCIP_CALL( applyVbounds(scip, heur, heurdata, heurdata->vbvars, heurdata->nvbvars, TRUE, 0,
1331  &skipobj1, &skipobj2, result) );
1332  }
1333  if( !skipobj1 && ((unsigned) heurdata->tightenvariant & VBOUNDVARIANT_BESTBOUND) != 0)
1334  {
1335  SCIP_CALL( applyVbounds(scip, heur, heurdata, heurdata->vbvars, heurdata->nvbvars, TRUE, 1, NULL, NULL, result) );
1336  }
1337  if( !skipobj2 && ((unsigned) heurdata->tightenvariant & VBOUNDVARIANT_WORSTBOUND) != 0)
1338  {
1339  SCIP_CALL( applyVbounds(scip, heur, heurdata, heurdata->vbvars, heurdata->nvbvars, TRUE, 2, NULL, NULL, result) );
1340  }
1341 
1342 #ifdef NOCONFLICT
1343  /* reset the conflict analysis */
1344  if( !SCIPisParamFixed(scip, "conflict/enable") )
1345  {
1346  SCIP_CALL( SCIPsetBoolParam(scip, "conflict/enable", enabledconflicts) );
1347  }
1348 #endif
1349 
1350  return SCIP_OKAY;
1351 }
1352 
1353 /*
1354  * primal heuristic specific interface methods
1355  */
1356 
1357 /** creates the vbounds primal heuristic and includes it in SCIP */
1359  SCIP* scip /**< SCIP data structure */
1360  )
1361 {
1362  SCIP_HEURDATA* heurdata;
1363  SCIP_HEUR* heur;
1364 
1365  /* create vbounds primal heuristic data */
1366  SCIP_CALL( SCIPallocBlockMemory(scip, &heurdata) );
1367  heurdataReset(heurdata);
1368 
1369  /* include primal heuristic */
1370  SCIP_CALL( SCIPincludeHeurBasic(scip, &heur,
1372  HEUR_MAXDEPTH, HEUR_TIMING, HEUR_USESSUBSCIP, heurExecVbounds, heurdata) );
1373 
1374  assert(heur != NULL);
1375 
1376  /* set non-NULL pointers to callback methods */
1377  SCIP_CALL( SCIPsetHeurCopy(scip, heur, heurCopyVbounds) );
1378  SCIP_CALL( SCIPsetHeurFree(scip, heur, heurFreeVbounds) );
1379  SCIP_CALL( SCIPsetHeurExitsol(scip, heur, heurExitsolVbounds) );
1380 
1381  /* add variable bounds primal heuristic parameters */
1382  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/minintfixingrate",
1383  "minimum percentage of integer variables that have to be fixed",
1384  &heurdata->minintfixingrate, FALSE, DEFAULT_MININTFIXINGRATE, 0.0, 1.0, NULL, NULL) );
1385 
1386  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/minmipfixingrate",
1387  "minimum percentage of variables that have to be fixed within sub-SCIP (integer and continuous)",
1388  &heurdata->minmipfixingrate, FALSE, DEFAULT_MINMIPFIXINGRATE, 0.0, 1.0, NULL, NULL) );
1389 
1390  SCIP_CALL( SCIPaddLongintParam(scip, "heuristics/" HEUR_NAME "/maxnodes",
1391  "maximum number of nodes to regard in the subproblem",
1392  &heurdata->maxnodes, TRUE,DEFAULT_MAXNODES, 0LL, SCIP_LONGINT_MAX, NULL, NULL) );
1393 
1394  SCIP_CALL( SCIPaddLongintParam(scip, "heuristics/" HEUR_NAME "/nodesofs",
1395  "number of nodes added to the contingent of the total nodes",
1396  &heurdata->nodesofs, FALSE, DEFAULT_NODESOFS, 0LL, SCIP_LONGINT_MAX, NULL, NULL) );
1397 
1398  SCIP_CALL( SCIPaddLongintParam(scip, "heuristics/" HEUR_NAME "/minnodes",
1399  "minimum number of nodes required to start the subproblem",
1400  &heurdata->minnodes, TRUE, DEFAULT_MINNODES, 0LL, SCIP_LONGINT_MAX, NULL, NULL) );
1401 
1402  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/nodesquot",
1403  "contingent of sub problem nodes in relation to the number of nodes of the original problem",
1404  &heurdata->nodesquot, FALSE, DEFAULT_NODESQUOT, 0.0, 1.0, NULL, NULL) );
1405 
1406  SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/minimprove",
1407  "factor by which " HEUR_NAME " heuristic should at least improve the incumbent",
1408  &heurdata->minimprove, TRUE, DEFAULT_MINIMPROVE, 0.0, 1.0, NULL, NULL) );
1409 
1410  SCIP_CALL( SCIPaddIntParam(scip, "heuristics/" HEUR_NAME "/maxproprounds",
1411  "maximum number of propagation rounds during probing (-1 infinity)",
1412  &heurdata->maxproprounds, TRUE, DEFAULT_MAXPROPROUNDS, -1, INT_MAX/4, NULL, NULL) );
1413 
1414  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/copycuts",
1415  "should all active cuts from cutpool be copied to constraints in subproblem?",
1416  &heurdata->copycuts, TRUE, DEFAULT_COPYCUTS, NULL, NULL) );
1417 
1418  SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/uselockfixings",
1419  "should more variables be fixed based on variable locks if the fixing rate was not reached?",
1420  &heurdata->uselockfixings, TRUE, DEFAULT_USELOCKFIXINGS, NULL, NULL) );
1421 
1422  SCIP_CALL( SCIPaddIntParam(scip, "heuristics/" HEUR_NAME "/maxbacktracks",
1423  "maximum number of backtracks during the fixing process",
1424  &heurdata->maxbacktracks, TRUE, DEFAULT_MAXBACKTRACKS, -1, INT_MAX/4, NULL, NULL) );
1425 
1426  SCIP_CALL( SCIPaddIntParam(scip, "heuristics/" HEUR_NAME "/feasvariant",
1427  "which variants of the vbounds heuristic that try to stay feasible should be called? (0: off, 1: w/o looking at obj, 2: only fix to best bound, 4: only fix to worst bound",
1428  &heurdata->feasvariant, TRUE, (int) DEFAULT_FEASVARIANT, 0, 7, NULL, NULL) );
1429 
1430  SCIP_CALL( SCIPaddIntParam(scip, "heuristics/" HEUR_NAME "/tightenvariant",
1431  "which tightening variants of the vbounds heuristic should be called? (0: off, 1: w/o looking at obj, 2: only fix to best bound, 4: only fix to worst bound",
1432  &heurdata->tightenvariant, TRUE, (int) DEFAULT_TIGHTENVARIANT, 0, 7, NULL, NULL) );
1433 
1434  return SCIP_OKAY;
1435 }
1436 
1437 /**@} */
enum SCIP_Result SCIP_RESULT
Definition: type_result.h:61
SCIP_RETCODE SCIPsetHeurExitsol(SCIP *scip, SCIP_HEUR *heur, SCIP_DECL_HEUREXITSOL((*heurexitsol)))
Definition: scip_heur.c:242
#define HEUR_TIMING
Definition: heur_vbounds.c:89
enum SCIP_BoundType SCIP_BOUNDTYPE
Definition: type_lp.h:59
int SCIPgetNIntVars(SCIP *scip)
Definition: scip_prob.c:2082
#define DEFAULT_NODESQUOT
Definition: heur_vbounds.c:102
SCIP_RETCODE SCIPlinkLPSol(SCIP *scip, SCIP_SOL *sol)
Definition: scip_sol.c:882
SCIP_Real SCIPgetSolvingTime(SCIP *scip)
Definition: scip_timing.c:378
SCIP_RETCODE SCIPsetSeparating(SCIP *scip, SCIP_PARAMSETTING paramsetting, SCIP_Bool quiet)
Definition: scip_param.c:979
SCIP_Real * SCIPvarGetVlbCoefs(SCIP_VAR *var)
Definition: var.c:18293
#define NULL
Definition: def.h:267
#define HEUR_USESSUBSCIP
Definition: heur_vbounds.c:90
SCIP_VAR ** SCIPcliqueGetVars(SCIP_CLIQUE *clique)
Definition: implics.c:3380
#define SCIPallocBlockMemoryArray(scip, ptr, num)
Definition: scip_mem.h:93
#define DEFAULT_NODESOFS
Definition: heur_vbounds.c:101
#define getVarIndex(idx)
Definition: heur_vbounds.c:167
public methods for SCIP parameter handling
SCIP_NODE * SCIPgetCurrentNode(SCIP *scip)
Definition: scip_tree.c:91
public methods for branch and bound tree
SCIP_RETCODE SCIPbacktrackProbing(SCIP *scip, int probingdepth)
Definition: scip_probing.c:225
SCIP_Longint SCIPgetNLPIterations(SCIP *scip)
SCIP_RETCODE SCIPincludeHeurVbounds(SCIP *scip)
#define DEFAULT_MININTFIXINGRATE
Definition: heur_vbounds.c:93
public methods for memory management
int SCIPgetProbingDepth(SCIP *scip)
Definition: scip_probing.c:198
#define SCIPallocClearBufferArray(scip, ptr, num)
Definition: scip_mem.h:126
int SCIPvarGetNVlbs(SCIP_VAR *var)
Definition: var.c:18271
static void heurdataReset(SCIP_HEURDATA *heurdata)
Definition: heur_vbounds.c:179
public methods for implications, variable bounds, and cliques
#define SCIP_MAXSTRLEN
Definition: def.h:288
SCIP_Longint SCIPheurGetNBestSolsFound(SCIP_HEUR *heur)
Definition: heur.c:1599
internal methods for clocks and timing issues
static long bound
SCIP_Bool SCIPisPositive(SCIP *scip, SCIP_Real val)
SCIP_Real SCIPvarGetLbLocal(SCIP_VAR *var)
Definition: var.c:18135
int SCIPgetNPseudoBranchCands(SCIP *scip)
Definition: scip_branch.c:758
SCIP_CLIQUE ** SCIPvarGetCliques(SCIP_VAR *var, SCIP_Bool varfixing)
Definition: var.c:18442
public solving methods
public methods for timing
#define VBOUNDVARIANT_BESTBOUND
Definition: heur_vbounds.c:79
#define getOtherBoundIndex(idx)
Definition: heur_vbounds.c:170
SCIP_RETCODE SCIPreleaseVar(SCIP *scip, SCIP_VAR **var)
Definition: scip_var.c:1247
SCIP_Bool SCIPvarIsBinary(SCIP_VAR *var)
Definition: var.c:17600
SCIP_RETCODE SCIPstopClock(SCIP *scip, SCIP_CLOCK *clck)
Definition: scip_timing.c:178
#define isIndexLowerbound(idx)
Definition: heur_vbounds.c:169
static SCIP_RETCODE initializeCandsLists(SCIP *scip, SCIP_HEURDATA *heurdata)
Definition: heur_vbounds.c:470
SCIP_RETCODE SCIPgetVarsData(SCIP *scip, SCIP_VAR ***vars, int *nvars, int *nbinvars, int *nintvars, int *nimplvars, int *ncontvars)
Definition: scip_prob.c:1866
int SCIPcliqueGetIndex(SCIP_CLIQUE *clique)
Definition: implics.c:3416
#define VBOUNDVARIANT_WORSTBOUND
Definition: heur_vbounds.c:80
#define FALSE
Definition: def.h:94
SCIP_RETCODE SCIPhashmapCreate(SCIP_HASHMAP **hashmap, BMS_BLKMEM *blkmem, int mapsize)
Definition: misc.c:3074
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:111
SCIP_RETCODE SCIPcopyLimits(SCIP *sourcescip, SCIP *targetscip)
Definition: scip_copy.c:3296
SCIP_RETCODE SCIPcutoffNode(SCIP *scip, SCIP_NODE *node)
Definition: scip_tree.c:434
SCIP_Real SCIPinfinity(SCIP *scip)
#define TRUE
Definition: def.h:93
SCIP_RETCODE SCIPapplyLockFixings(SCIP *scip, SCIP_HEURDATA *heurdata, SCIP_Bool *cutoff, SCIP_Bool *allrowsfulfilled)
Definition: heur_locks.c:196
enum SCIP_Retcode SCIP_RETCODE
Definition: type_retcode.h:63
static SCIP_RETCODE applyVboundsFixings(SCIP *scip, SCIP_HEURDATA *heurdata, SCIP_VAR **vars, int nvbvars, SCIP_Bool tighten, int obj, SCIP_Bool *allobj1, SCIP_Bool *allobj2, SCIP_Bool *backtracked, SCIP_Bool *infeasible)
Definition: heur_vbounds.c:558
#define SCIPstatisticMessage
Definition: pub_message.h:123
int SCIPvarGetNVubs(SCIP_VAR *var)
Definition: var.c:18313
SCIP_RETCODE SCIPsetPresolving(SCIP *scip, SCIP_PARAMSETTING paramsetting, SCIP_Bool quiet)
Definition: scip_param.c:953
SCIP_BRANCHRULE * SCIPfindBranchrule(SCIP *scip, const char *name)
Definition: scip_branch.c:297
#define DEFAULT_MINIMPROVE
Definition: heur_vbounds.c:97
int SCIPvarGetProbindex(SCIP_VAR *var)
Definition: var.c:17769
struct SCIP_HeurData SCIP_HEURDATA
Definition: type_heur.h:77
public methods for problem variables
#define SCIPfreeBlockMemory(scip, ptr)
Definition: scip_mem.h:108
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:117
#define SCIPdebugMessage
Definition: pub_message.h:96
SCIP_RETCODE SCIPtranslateSubSols(SCIP *scip, SCIP *subscip, SCIP_HEUR *heur, SCIP_VAR **subvars, SCIP_Bool *success, int *solindex)
Definition: scip_copy.c:1448
SCIP_RETCODE SCIPchgVarLbProbing(SCIP *scip, SCIP_VAR *var, SCIP_Real newbound)
Definition: scip_probing.c:301
SCIP_VAR ** SCIPvarGetVlbVars(SCIP_VAR *var)
Definition: var.c:18283
#define DEFAULT_MAXNODES
Definition: heur_vbounds.c:92
SCIP_RETCODE SCIPfreeClock(SCIP *scip, SCIP_CLOCK **clck)
Definition: scip_timing.c:127
void * SCIPhashmapGetImage(SCIP_HASHMAP *hashmap, void *origin)
Definition: misc.c:3261
SCIP_RETCODE SCIPconstructLP(SCIP *scip, SCIP_Bool *cutoff)
Definition: scip_lp.c:124
#define DEFAULT_MAXBACKTRACKS
Definition: heur_vbounds.c:104
#define SCIP_LONGINT_MAX
Definition: def.h:159
#define SCIPfreeBufferArray(scip, ptr)
Definition: scip_mem.h:136
enum SCIP_LPSolStat SCIP_LPSOLSTAT
Definition: type_lp.h:51
SCIP_RETCODE SCIPcreate(SCIP **scip)
Definition: scip_general.c:307
void SCIPheurSetData(SCIP_HEUR *heur, SCIP_HEURDATA *heurdata)
Definition: heur.c:1374
#define SCIPallocBlockMemory(scip, ptr)
Definition: scip_mem.h:89
public methods for SCIP variables
void SCIPwarningMessage(SCIP *scip, const char *formatstr,...)
Definition: scip_message.c:120
#define SCIPdebugMsg
Definition: scip_message.h:78
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:83
SCIP_RETCODE SCIPprintStatistics(SCIP *scip, FILE *file)
int SCIPvarGetNCliques(SCIP_VAR *var, SCIP_Bool varfixing)
Definition: var.c:18431
#define HEUR_NAME
Definition: heur_vbounds.c:82
#define DEFAULT_FEASVARIANT
Definition: heur_vbounds.c:115
public methods for numerical tolerances
#define getUbIndex(idx)
Definition: heur_vbounds.c:166
public methods for querying solving statistics
const char * SCIPgetProbName(SCIP *scip)
Definition: scip_prob.c:1067
#define HEUR_PRIORITY
Definition: heur_vbounds.c:85
public methods for the branch-and-bound tree
SCIP_Bool SCIPisLPConstructed(SCIP *scip)
Definition: scip_lp.c:101
SCIP_Longint SCIPnodeGetNumber(SCIP_NODE *node)
Definition: tree.c:7490
SCIP_Bool SCIPisLPSolBasic(SCIP *scip)
Definition: scip_lp.c:667
SCIP_RETCODE SCIPsolve(SCIP *scip)
Definition: scip_solve.c:2498
const char * SCIPheurGetName(SCIP_HEUR *heur)
Definition: heur.c:1453
SCIP_RETCODE SCIPcreateClock(SCIP *scip, SCIP_CLOCK **clck)
Definition: scip_timing.c:76
static SCIP_RETCODE topologicalSort(SCIP *scip, int *vbvars, int *nvbvars)
Definition: heur_vbounds.c:422
SCIP_Bool SCIPisParamFixed(SCIP *scip, const char *name)
Definition: scip_param.c:219
SCIP_RETCODE SCIPsetHeurFree(SCIP *scip, SCIP_HEUR *heur, SCIP_DECL_HEURFREE((*heurfree)))
Definition: scip_heur.c:178
SCIP_RETCODE SCIPpropagateProbing(SCIP *scip, int maxproprounds, SCIP_Bool *cutoff, SCIP_Longint *ndomredsfound)
Definition: scip_probing.c:580
SCIP_RETCODE SCIPfixVarProbing(SCIP *scip, SCIP_VAR *var, SCIP_Real fixedval)
Definition: scip_probing.c:418
#define HEUR_DESC
Definition: heur_vbounds.c:83
SCIP_RETCODE SCIPsetBoolParam(SCIP *scip, const char *name, SCIP_Bool value)
Definition: scip_param.c:429
SCIP_STATUS SCIPgetStatus(SCIP *scip)
Definition: scip_general.c:498
SCIP_RETCODE SCIPpresolve(SCIP *scip)
Definition: scip_solve.c:2328
SCIP_RETCODE SCIPcopyCuts(SCIP *sourcescip, SCIP *targetscip, SCIP_HASHMAP *varmap, SCIP_HASHMAP *consmap, SCIP_Bool global, int *ncutsadded)
Definition: scip_copy.c:2130
BMS_BLKMEM * SCIPblkmem(SCIP *scip)
Definition: scip_mem.c:57
static SCIP_DECL_HEURCOPY(heurCopyVbounds)
SCIP_RETCODE SCIPendProbing(SCIP *scip)
Definition: scip_probing.c:260
const char * SCIPvarGetName(SCIP_VAR *var)
Definition: var.c:17420
SCIP_Real SCIPclockGetTime(SCIP_CLOCK *clck)
Definition: clock.c:438
char * SCIPsnprintfProbingStats(SCIP *scip, char *strbuf, int len)
void SCIPhashmapFree(SCIP_HASHMAP **hashmap)
Definition: misc.c:3108
SCIP_RETCODE SCIPgetBoolParam(SCIP *scip, const char *name, SCIP_Bool *value)
Definition: scip_param.c:250
#define SCIP_Shortbool
Definition: def.h:99
#define HEUR_FREQ
Definition: heur_vbounds.c:86
public methods for problem copies
#define DEFAULT_MINMIPFIXINGRATE
Definition: heur_vbounds.c:94
int SCIPgetNUnfixedLPCols(SCIP *scip)
Definition: scip_lp.c:548
#define SCIP_CALL(x)
Definition: def.h:380
SCIP_Real SCIPgetLowerbound(SCIP *scip)
SCIP_RETCODE SCIPsolveProbingLP(SCIP *scip, int itlim, SCIP_Bool *lperror, SCIP_Bool *cutoff)
Definition: scip_probing.c:820
void SCIPverbMessage(SCIP *scip, SCIP_VERBLEVEL msgverblevel, FILE *file, const char *formatstr,...)
Definition: scip_message.c:225
static SCIP_RETCODE setupAndSolveSubscip(SCIP *scip, SCIP *subscip, SCIP_HEUR *heur, SCIP_VAR **vars, int nvars, SCIP_Longint nstallnodes, SCIP_Real lowerbound, int *nprevars, SCIP_Bool *wasfeas, SCIP_RESULT *result)
Definition: heur_vbounds.c:739
static SCIP_RETCODE dfs(SCIP *scip, int startnode, SCIP_Shortbool *visited, int *dfsstack, int *stacknextedge, int *stacknextcliquevar, int *cliqueexit, int *dfsnodes, int *ndfsnodes)
Definition: heur_vbounds.c:193
SCIP_Real * SCIPvarGetVubCoefs(SCIP_VAR *var)
Definition: var.c:18335
#define DEFAULT_MINNODES
Definition: heur_vbounds.c:100
SCIP_Longint SCIPheurGetNCalls(SCIP_HEUR *heur)
Definition: heur.c:1579
static SCIP_DECL_HEUREXEC(heurExecVbounds)
SCIP_Bool SCIPhasCurrentNodeLP(SCIP *scip)
Definition: scip_lp.c:83
public methods for primal heuristic plugins and divesets
public methods for constraint handler plugins and constraints
#define DEFAULT_TIGHTENVARIANT
Definition: heur_vbounds.c:118
SCIP_RETCODE SCIPcopyConsCompression(SCIP *sourcescip, SCIP *targetscip, SCIP_HASHMAP *varmap, SCIP_HASHMAP *consmap, const char *suffix, SCIP_VAR **fixedvars, SCIP_Real *fixedvals, int nfixedvars, SCIP_Bool global, SCIP_Bool enablepricing, SCIP_Bool threadsafe, SCIP_Bool passmessagehdlr, SCIP_Bool *valid)
Definition: scip_copy.c:2969
#define SCIPallocBufferArray(scip, ptr, num)
Definition: scip_mem.h:124
#define DEFAULT_COPYCUTS
Definition: heur_vbounds.c:105
public data structures and miscellaneous methods
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:3251
#define SCIP_Bool
Definition: def.h:91
SCIP_LPSOLSTAT SCIPgetLPSolstat(SCIP *scip)
Definition: scip_lp.c:168
int SCIPgetNImplVars(SCIP *scip)
Definition: scip_prob.c:2127
static SCIP_DECL_HEUREXITSOL(heurExitsolVbounds)
SCIP_RETCODE SCIProundSol(SCIP *scip, SCIP_SOL *sol, SCIP_Bool *success)
Definition: scip_sol.c:2311
SCIP_RETCODE SCIPsetObjlimit(SCIP *scip, SCIP_Real objlimit)
Definition: scip_prob.c:1422
int SCIPgetDepth(SCIP *scip)
Definition: scip_tree.c:670
#define MIN(x, y)
Definition: def.h:243
SCIP_Bool * SCIPcliqueGetValues(SCIP_CLIQUE *clique)
Definition: implics.c:3392
SCIP_RETCODE SCIPsetIntParam(SCIP *scip, const char *name, int value)
Definition: scip_param.c:487
SCIP_RETCODE SCIPfreeSol(SCIP *scip, SCIP_SOL **sol)
Definition: scip_sol.c:841
void SCIPenableVarHistory(SCIP *scip)
Definition: scip_var.c:8740
SCIP_Real SCIPvarGetObj(SCIP_VAR *var)
Definition: var.c:17927
LNS heuristic uses the variable lower and upper bounds to determine the search neighborhood.
int SCIPgetNSols(SCIP *scip)
Definition: scip_sol.c:2070
SCIP_Real SCIPgetSolOrigObj(SCIP *scip, SCIP_SOL *sol)
Definition: scip_sol.c:1300
SCIP_RETCODE SCIPflushLP(SCIP *scip)
Definition: scip_lp.c:148
locks primal heuristic
SCIP_Bool SCIPisInfinity(SCIP *scip, SCIP_Real val)
#define getLbIndex(idx)
Definition: heur_vbounds.c:165
SCIP_RETCODE SCIPtrySol(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:2954
#define SCIP_MAXTREEDEPTH
Definition: def.h:316
int SCIPgetNBinVars(SCIP *scip)
Definition: scip_prob.c:2037
SCIP_Bool SCIPinProbing(SCIP *scip)
Definition: scip_probing.c:97
public methods for the LP relaxation, rows and columns
int SCIPgetNVars(SCIP *scip)
Definition: scip_prob.c:1992
#define SCIP_LONGINT_FORMAT
Definition: def.h:165
public methods for branching rule plugins and branching
#define getBoundtype(idx)
Definition: heur_vbounds.c:168
#define HEUR_FREQOFS
Definition: heur_vbounds.c:87
general public methods
#define MAX(x, y)
Definition: def.h:239
SCIP_Real SCIPgetLPObjval(SCIP *scip)
Definition: scip_lp.c:247
public methods for solutions
#define HEUR_MAXDEPTH
Definition: heur_vbounds.c:88
int SCIPgetNConss(SCIP *scip)
Definition: scip_prob.c:3042
#define DEFAULT_USELOCKFIXINGS
Definition: heur_vbounds.c:108
public methods for the probing mode
public methods for message output
int SCIPgetNCliques(SCIP *scip)
Definition: scip_var.c:7574
SCIP_VAR ** SCIPgetVars(SCIP *scip)
Definition: scip_prob.c:1947
#define SCIPstatistic(x)
Definition: pub_message.h:120
SCIP_RETCODE SCIPcaptureVar(SCIP *scip, SCIP_VAR *var)
Definition: scip_var.c:1213
#define SCIP_Real
Definition: def.h:173
SCIP_Bool SCIPisStopped(SCIP *scip)
Definition: scip_general.c:724
public methods for message handling
SCIP_VAR ** SCIPvarGetVubVars(SCIP_VAR *var)
Definition: var.c:18325
#define SCIP_Longint
Definition: def.h:158
SCIP_RETCODE SCIPcheckCopyLimits(SCIP *sourcescip, SCIP_Bool *success)
Definition: scip_copy.c:3253
SCIP_VARTYPE SCIPvarGetType(SCIP_VAR *var)
Definition: var.c:17585
int SCIPgetNLPCols(SCIP *scip)
Definition: scip_lp.c:527
SCIP_RETCODE SCIPsetHeurCopy(SCIP *scip, SCIP_HEUR *heur, SCIP_DECL_HEURCOPY((*heurcopy)))
Definition: scip_heur.c:162
SCIP_Real SCIPvarGetUbLocal(SCIP_VAR *var)
Definition: var.c:18145
#define SCIPfreeBlockMemoryArrayNull(scip, ptr, num)
Definition: scip_mem.h:111
SCIP_RETCODE SCIPnewProbingNode(SCIP *scip)
Definition: scip_probing.c:165
int SCIPcliqueGetNVars(SCIP_CLIQUE *clique)
Definition: implics.c:3370
SCIP_Real SCIPsumepsilon(SCIP *scip)
SCIP_Real SCIPgetUpperbound(SCIP *scip)
SCIP_RETCODE SCIPstartProbing(SCIP *scip)
Definition: scip_probing.c:119
public methods for primal heuristics
#define SCIP_CALL_ABORT(x)
Definition: def.h:359
SCIP_HEURDATA * SCIPheurGetData(SCIP_HEUR *heur)
Definition: heur.c:1364
static SCIP_DECL_HEURFREE(heurFreeVbounds)
SCIP_Longint SCIPgetNNodes(SCIP *scip)
#define VBOUNDVARIANT_NOOBJ
Definition: heur_vbounds.c:78
public methods for global and local (sub)problems
SCIP_Bool SCIPvarIsIntegral(SCIP_VAR *var)
Definition: var.c:17611
SCIP_RETCODE SCIPchgVarUbProbing(SCIP *scip, SCIP_VAR *var, SCIP_Real newbound)
Definition: scip_probing.c:345
SCIP_RETCODE SCIPstartClock(SCIP *scip, SCIP_CLOCK *clck)
Definition: scip_timing.c:161
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:139
SCIP_RETCODE SCIPsetSubscipsOff(SCIP *scip, SCIP_Bool quiet)
Definition: scip_param.c:904
SCIP_RETCODE SCIPsetLongintParam(SCIP *scip, const char *name, SCIP_Longint value)
Definition: scip_param.c:545
#define HEUR_DISPCHAR
Definition: heur_vbounds.c:84
static SCIP_RETCODE applyVbounds(SCIP *scip, SCIP_HEUR *heur, SCIP_HEURDATA *heurdata, SCIP_VAR **vbvars, int nvbvars, SCIP_Bool tighten, int obj, SCIP_Bool *skipobj1, SCIP_Bool *skipobj2, SCIP_RESULT *result)
Definition: heur_vbounds.c:900
#define DEFAULT_MAXPROPROUNDS
Definition: heur_vbounds.c:103
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:57
SCIP_Bool SCIPvarIsActive(SCIP_VAR *var)
Definition: var.c:17749
SCIP_RETCODE SCIPfree(SCIP **scip)
Definition: scip_general.c:339
SCIP_RETCODE SCIPcreateSol(SCIP *scip, SCIP_SOL **sol, SCIP_HEUR *heur)
Definition: scip_sol.c:184
memory allocation routines