[Coin-discuss] Cbc, Symphony, and GLPK

[John J Forrest]

For Cbc I am unable to reproduce problem on Linux.  driver4 and stand-alone
cbc with various option permutations all gave the answer of -

BINV0001, 04, 10 and 14 at 1 and rest at 0.

which when the problem with all binary variables fixed is solved does not
seem to violate the constraints.  Which constraints do you think  that
solution violates?

John Forrest


                                                                                                                
  From:       "Cheng,Jen-Min" <jcheng at mwdh2o.com>                                                               
                                                                                                                
  To:         <coin-discuss at list.coin-or.org>                                                                   
                                                                                                                
  Cc:         "Louie,Peter W" <plouie at mwdh2o.com>                                                               
                                                                                                                
  Date:       06/02/2009 01:32 PM                                                                               
                                                                                                                
  Subject:    [Coin-discuss] Cbc, Symphony, and GLPK                                                            
                                                                                                                






Microsoft Visual Studio 2008 has been used to generate executables for Cbc
driver4 2.3, Symphony 5.2, and GLPK 4.38.  These executables can solve many
MIPLIB 2003 problems.  Cbc driver4 2.3 did outperform other two solvers in
solving these MIPLIB 2003 problemsr as Cbc developers had claimed.

An artificial example of water supply and allocation had been created and
tested with Cbc driver4, Symphony, and GLPK.  GLPK produced a feasible
solution.  Symphony 5.2 produced a feasible solution, which violated
several constraints.  Cbc driver4 2.3 generated a feasible solution, which
violated more constraints than Symphony 5.2.

The mps file is attached.  Will any please find out why Cbc and Symphony
cannot produce a feasible solution.

Thanks for your time and help.

 [attachment "test100.mps" deleted by John J Forrest/Watson/IBM]
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