[Cbc-tickets] [COIN-OR Branch-and-Cut MIP Solver] #55: CBC produce wrong solution and inconsistent solution between CBC 2.2 and CBC trunk

[COIN-OR Branch-and-Cut MIP Solver]

#55: CBC produce wrong solution and inconsistent solution between CBC 2.2 and
CBC trunk
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 Reporter:  cents                     |       Owner:  somebody
     Type:  defect                    |      Status:  new     
 Priority:  major                     |   Milestone:          
Component:  component1                |     Version:          
 Keywords:  CBC wrong solution trunk  |  
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 I am trying to use CBC to solve two MIP problems.  I downloaded 2.2 stable
 release and trunk and compiled both version on a Linux Ubuntu Hardy Heron
 distribution.

 For the first problem test1.mps.  CBC2.2 appears produce correct result
 but CBC trunk does not produce correct result and the two results are
 quite different.

 For the second problem test2.mps, which is only slightly different from
 test1.mps.  CBC2.2 does generated a solution (I am not sure whether the
 solution is correct or not), however the objective value in the solution
 file is obviously wrong because you get a different result by calculating
 the objective value from the provided solution for the variables. CBC
 trunk does not seems to solve the problem and produce a different result
 from CBC2.2.

 I used the following command to run the program.

 cbc mps_file -max -solve -solution solution file > outputfile

 I have attached the mps files and output files in a tgz file for both
 problems.

 test1.mps  #mps for problem 1
 test1.solution # solution by CBC 2.2
 test1.output  # output by CBC2.2
 test1_trunk.solution #solution by CBC trunk
 test1_trunk.output # output by CBC trunk

 test2.mps  #mps for problem 2
 test2.solution # solution by CBC 2.2
 test2.output  # output by CBC2.2
 test2_trunk.solution #solution by CBC trunk
 test2_trunk.output # output by CBC trunk

 Please advice.

 Jun

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Ticket URL: <https://projects.coin-or.org/Cbc/ticket/55>
COIN-OR Branch-and-Cut MIP Solver <http://projects.coin-or.org/Cbc>
An LP-based branch-and-cut MIP solver.