[Cbc-tickets] [COIN-OR Branch-and-Cut MIP Solver] #56: CBC produce wrong solution and inconsistent solution between CBC 2.2 and CBC trunk

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

#56: 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:  2.0     
 Keywords:  wrong solution inconsistent objective  |  
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 I tried to use CBC to solve two MIP problems.  I downloaded CBC 2.2 and
 trunk and compiled them on a Ubuntu Linux (latest version Hardy Heron).
 The CBC trunk is download today (9-09-2008)

 For the first problem test1.mps. CBC2.2  appears to produce correct
 solution. However, CBC trunk produce a different solution and is very
 likely to be wrong.

 For the second problem test2.mps.  The solution produced by CBC2.2 appears
 to have a wrong objective value because the objective value is different
 from the one calculated from the variable solutions. I am not sure whether
 this solution is correct or not. CBC trunk produce a different solution
 and might be wrong as well.

 I use the following command to run CBC

 cbc mps_file -max -solve -solution solution_file > output_file

 I have attached the mps files, the solution files as well as the output
 for both problems from both version of CBC. The files are compress using
 tar and bzip to reduce the size to the allowed attachment size for the
 ticket.  Use "tar -xjf test.tjz" to uncompress the files.

 Detail description of the files.

 test1.mps # mps file for problem 1

 test1.solution #CBC2.2 solution for problem 1

 test1.output # CBC2.2 output for problem 1

 test1_trunk.solution #CBC trunk solution for problem 1

 test1_trunk.output #CBC trunk output for problem 1

 test2.mps # mps file for problem 2

 test2.solution #CBC2.2 solution for problem 2

 test2.output # CBC2.2 output for problem 2

 test2_trunk.solution #CBC trunk solution for problem 2

 test2_trunk.output #CBC trunk output for problem 2

 Please advise.

 Jun

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Ticket URL: <https://projects.coin-or.org/Cbc/ticket/56>
COIN-OR Branch-and-Cut MIP Solver <http://projects.coin-or.org/Cbc>
An LP-based branch-and-cut MIP solver.