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Re: [Bug-glpk] Wrong result with MIP presolver - NO PRIMAL FEASIBLE SOLU
From: |
Andrew Makhorin |
Subject: |
Re: [Bug-glpk] Wrong result with MIP presolver - NO PRIMAL FEASIBLE SOLUTION |
Date: |
Thu, 01 Jan 2015 16:13:35 +0300 |
Hi Heinrich,
Thank you for your bug report.
> for the appended model I get the following results with glpk 4.55 on Linux
> 64bit:
>
> $ glpsol -m test.mod
> ...
> Preprocessing...
> PROBLEM HAS NO PRIMAL FEASIBLE SOLUTION
>
> $ glpsol --nointopt -m test.mod
> ...
> +356119: mip = 0.000000000e+00 >= tree is empty 0.0% (0; 3059)
> INTEGER OPTIMAL SOLUTION FOUND
> Time used: 161.6 secs
>
> The presolver should not influence reported feasiblity.
It may happen due to insufficient accuracy in the mip presolver. I will
try to inspect your instance more carefully.
Andrew Makhorin