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Re: [Bug-glpk] GLPK crashes on glp_add_cols

From: Chris Matrakidis
Subject: Re: [Bug-glpk] GLPK crashes on glp_add_cols
Date: Thu, 25 Apr 2019 18:02:25 +0300

This seems like a presolver issue. A big hint is the following:
3 rows, 0 columns, 0 non-zeros
0 integer variables, none of which are binary
Indeed, disabling the mip presolver with --nointopt works as expected: "PROBLEM HAS NO INTEGER FEASIBLE SOLUTION"

Tracing this a bit, the root cause seems to be the rather relaxed tolerance in npp_empty_row() - setting it to 1e-5 (from 1e-3) avoids this issue. Andrew, what do you think?

PS. The actual crash is due to the glp_add_cols() call in ios_create_pool(), maybe this should be made conditional as well. Note that with this change the crash is avoided but the solver finds a (wrong) solution to the problem.

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