[SCIP] TR: scip crash

Tue Jul 5 11:30:47 CEST 2016

Last version of CBC also solves this problem without detecting infeasibility.
I do not know very well Scip (and soplex) and maybe someone has an idea to get Scip working normally for this instance.
I tried modifying some parameters and tolerance but without success for the moment.

De : zjuzw at sohu.com [mailto:zjuzw at sohu.com]
Envoyé : mardi 5 juillet 2016 11:03
À : Derhy Nicolas (ENGIE) <nicolas.derhy at engie.com>; scip <scip at zib.de>
Objet : Re: [SCIP] TR: scip crash

Hello nicolas:

  Fortunately,it is a mixed 0-1 integer programming problem,and successfully solved by CPLEX.

  The result is as follows:

Welcome to IBM(R) ILOG(R) CPLEX(R) Interactive Optimizer 12.6.3.0
  with Simplex, Mixed Integer & Barrier Optimizers
5725-A06 5725-A29 5724-Y48 5724-Y49 5724-Y54 5724-Y55 5655-Y21
Copyright IBM Corp. 1988, 2015.  All Rights Reserved.

Type 'help' for a list of available commands.
Type 'help' followed by a command name for more
information on commands.

CPLEX> read bug.mps
Selected objective sense:  MINIMIZE
Selected objective  name:  C
Selected RHS        name:  RHS1
Selected range      name:  RNG1
Selected bound      name:  BND1
Problem 'bug.mps' read.
Read time = 0.16 sec. (0.79 ticks)
CPLEX> optimize
Tried aggregator 5 times.
MIP Presolve eliminated 1629 rows and 1354 columns.
MIP Presolve modified 1110 coefficients.
Aggregator did 268 substitutions.
Reduced MIP has 307 rows, 276 columns, and 919 nonzeros.
Reduced MIP has 119 binaries, 0 generals, 0 SOSs, and 0 indicators.
Presolve time = 0.06 sec. (4.38 ticks)
Found incumbent of value 1.0991956e+018 after 0.17 sec. (4.97 ticks)
Probing fixed 13 vars, tightened 21 bounds.
Probing time = 0.00 sec. (0.09 ticks)
Tried aggregator 2 times.
MIP Presolve eliminated 103 rows and 101 columns.
MIP Presolve modified 79 coefficients.
Aggregator did 6 substitutions.
Reduced MIP has 197 rows, 169 columns, and 578 nonzeros.
Reduced MIP has 67 binaries, 0 generals, 0 SOSs, and 0 indicators.
Presolve time = 0.00 sec. (0.60 ticks)
Probing fixed 0 vars, tightened 1 bounds.
Probing time = 0.00 sec. (0.05 ticks)
Tried aggregator 1 time.
MIP Presolve eliminated 10 rows and 12 columns.
MIP Presolve modified 13 coefficients.
Reduced MIP has 187 rows, 157 columns, and 554 nonzeros.
Reduced MIP has 63 binaries, 0 generals, 0 SOSs, and 0 indicators.
Presolve time = 0.00 sec. (0.32 ticks)
Probing time = 0.00 sec. (0.04 ticks)
Clique table members: 14.
MIP emphasis: balance optimality and feasibility.
MIP search method: dynamic search.
Parallel mode: deterministic, using up to 4 threads.
Root relaxation solution time = 0.00 sec. (0.39 ticks)

        Nodes                                         Cuts/
   Node  Left     Objective  IInf  Best Integer    Best Bound    ItCnt     Gap

*     0+    0                      1.09920e+018  8.18653e+017            25.52%
*     0+    0                      8.50858e+017  8.18653e+017             3.78%
      0     0  8.22495e+017     4  8.50858e+017  8.22495e+017        8    3.33%
*     0+    0                      8.25697e+017  8.22495e+017             0.39%
      0     0  8.22495e+017     5  8.25697e+017      Cuts: 16       20    0.39%
*     0+    0                      8.22495e+017  8.22495e+017             0.00%
      0     0        cutoff        8.22495e+017  8.22495e+017       20    0.00%
Elapsed time = 0.23 sec. (11.98 ticks, tree = 0.00 MB, solutions = 3)

Clique cuts applied:  3
Implied bound cuts applied:  5
Mixed integer rounding cuts applied:  2
Gomory fractional cuts applied:  4

Root node processing (before b&c):
  Real time             =    0.25 sec. (12.05 ticks)
Parallel b&c, 4 threads:
  Real time             =    0.00 sec. (0.00 ticks)
  Sync time (average)   =    0.00 sec.
  Wait time (average)   =    0.00 sec.
                          ------------
Total (root+branch&cut) =    0.25 sec. (12.05 ticks)

Solution pool: 4 solutions saved.

MIP - Integer optimal solution:  Objective = 8.2249485120e+017
Solution time =    0.61 sec.  Iterations = 20  Nodes = 0
Deterministic time = 12.06 ticks  (19.83 ticks/sec)

  But the global optimization solvers,such as SCIP,BARON,COUENNE,can't bring the same result as CPLEX.

  Does it mean that Soplex is inferior to CPLEX,which serves as the default linear programming solver in SCIP?

  Best Wishes,

  From Wei.

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