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Re: [Bug-glpk] Problem to solve MIP problem

From: Andrew Makhorin
Subject: Re: [Bug-glpk] Problem to solve MIP problem
Date: Mon, 27 Oct 2008 20:18:34 +0300

> I have this problem:

> When I use this routine (lpx_intopt(glpkProbPtr)), my problem is solved
> normally.

> But, when I use this routine
> (glp_intopt(glpkProbPtr,&glpkParamMipPtr)), my
> problem doesn't solve the problem.

> The error message is: glp_intopt: optimal basis to initial LP relaxation not
> provided

> I don't unsderstand. None parameters are passed at glpkParamMipPtr.

> Just, I initialize glpkParamMipPtr with glp_init_iocp(&glpkParamMipPtr);

> why?

If the mip presolver is disabled (by default it is disabled),
glp_intopt expects the current basis of lp relaxation to be optimal.
To resolve the issue you should either enable the mip presolver or
call glp_simplex before a call to glp_intopt to find optimal basic
solution to the lp relaxation.

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