[Bug-glpk] [Fwd: Re: Model causes glpk to hang]

[Andrew Makhorin]

-------- Forwarded Message --------
From: Yori Zwols <address@hidden>
To: address@hidden
Subject: Re: Model causes glpk to hang
Date: Sun, 17 May 2015 22:46:39 +0100

And the following model: 


var x1 >= 0, integer;
var x2 >= 0, integer;


subject to c1: x1 - 1.0001 * x2 >= 0.9;
subject to c2: x1 - x2 <= 0.8;


results in an assertion failure:


GLPSOL: GLPK LP/MIP Solver, v4.55
Parameter(s) specified in the command line:
 --math /home/yori/glpk-fail2.mod
Reading model section from /home/yori/glpk-fail2.mod...
/home/yori/glpk-fail2.mod:7: warning: unexpected end of file; missing
end statement inserted
7 lines were read
Generating c1...
Generating c2...
Model has been successfully generated
GLPK Integer Optimizer, v4.55
2 rows, 2 columns, 4 non-zeros
2 integer variables, none of which are binary
Preprocessing...
Assertion failed: q->lb < q->ub
Error detected in file glpnpp03.c at line 557
Aborted





Yori

On Sun, May 17, 2015 at 10:43 PM, Yori Zwols <address@hidden> wrote:
        The following model causes glpk to hang at the preprocessing
        stage. To reproduce this behavior, save this to a file, say,
        model.mod, and run: glpsol --math model.mod
        
        
        var x1 >= 0, integer;
        var x2 >= 0, integer;
        
        
        subject to c1: x1 - x2 >= 0.9;
        subject to c2: x1 - x2 <= 0.8;
        
        
        I have verified that this is still a bug in GLPK 4.55.
        
        Yori