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Re: [Help-glpk] "The conflict graph is either empty or too big"

From: Haroldo Santos
Subject: Re: [Help-glpk] "The conflict graph is either empty or too big"
Date: Mon, 14 May 2012 11:43:37 -0300

On Mon, May 14, 2012 at 11:40 AM, spiritfire <address@hidden> wrote:


I'm running a simulation and it's taking quite a while...

I'm running on Gusek, which is the only way I found to use GLPK (couldn't
figure out how to install on win)

The program seems to found a solution :

Integer optimization begins...
Gomory's cuts enabled
MIR cuts enabled
Cover cuts enabled
Clique cuts enabled
Creating the conflict graph...
The conflict graph is either empty or too big

But then it goes on searching for quite a while : simul.mod

Time used: 1294.0 secs.  Memory used: 55.1 Mb.
+176120: mip =     not found yet >=  5.813433080e+004        (195; 6)
+176321: mip =     not found yet >=  5.813433080e+004        (196; 6)

I have no clue if it's close to the solution, if it's taking too long or if
I should wait or ... ?

Does anybody know if it is normal ?
Perfectly normal. Integer programming is hard and solvers can take enormous amount of time to solve it.
You could try:
  - use another solver
  - improve your formulation
  - try different glpsol parameters (ex.: fpump )

my code is attached.

Thank you.
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Haroldo Gambini Santos
Computing Department - Universidade Federal de Ouro Preto - UFOP
email: haroldo [at ]
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"Computer science is no more about computers than astronomy
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