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Re: [Bug-glpk] LP reader cannot read empty constraints

From: Andrew Makhorin
Subject: Re: [Bug-glpk] LP reader cannot read empty constraints
Date: Wed, 04 Dec 2013 15:21:54 +0400

On Wed, 2013-12-04 at 20:43 +0930, Sean Ma wrote:
> Thanks very much for your quick reply.
> Sorry I did not provide my test case. Acutally, the generated LP file
> from CPLEX 12.0 has the following empty constraint:
> Subject To
>  F1X.0:    = 0
> there is no variable in the constraint, that's why GLPK indicted an error.
> I think the previous form is common. If the RHS is not zero, then
> during preprocessing, there problem will be detected infeasible.
> The reason I reported this as a bug to you because we have also used
> many other LP/MIP solvers, all of them can read the above empty
> constraint correctly. I was just wondering it might be reasonable to
> consider the above form as acceptable.

Now it is understood. IIRC the cplex manual I used says nothing about
this option. Okay, I will change the lp reader in a next glpk release.
Thank you.

Andrew Makhorin

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