Re: [Bug-glpk] glpk_intopt loops forever on a specific input when MIP presolver enabled

[Chris Matrakidis]

Andrew,

--nopresol option affects only lp, not mip.

Actually, if --nointopt is specified, then the glp_simplex() call in glpsol.c will use the lp presolver parameters, so --nopresol is also needed to completely disable presolving.  

 

> Also "glpsol --lp --nointopt problem.lp" works which points to the MIP
> presolver as the "faulty" part.

Yes, glpsol fails on your instance because of the mip preprocessor.

In this case, the mip preprocessor does not look like it is doing a lot more than the lp one. The difference is due to the additional power of 2 scaling done in this case (together with the preprocessing changes of course).

Hopefully, this observation will help you isolate the issue.

Best Regards,

Chris Matrakidis