[Cbc] confusing solution

[Mike Steglich]

Hello,

I've got an interesting behaviour with the attached mps file. When I run this problem with the CBC binary (2.8.9 on OS X and 2.9.0 on Win8.1) then I got the following information:

...
Coin0505I Presolved problem not optimal, resolve after postsolve
Cgl0013I Postprocessed model is infeasible - possible tolerance issue - try without preprocessing
16 relaxed row infeasibilities - summing to 193
16 relaxed row infeasibilities - summing to 193
16 relaxed row infeasibilities - summing to 193

Result - Optimal solution found

Objective value:                813.00000000
...

The solution file (It doesn't matter whether I use the solu or gsolu option) shows an different objective function value of 1925 and values for the variables that are obviously infeasible.  When I set the preprocessing off then the problem is stated as infeasible.

It could be possible that the problem formulation and therefore the mps file is stupid. But when I use the same mps file with glpk, scip and Cplex then I'm able to find in any case an optimal solution with the objective function value 813 (that is also shown by Cbc).




Thanks,

Mike
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