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Re: [Bug-glpk] unexpected ending at 4.xx%


From: Andrew Makhorin
Subject: Re: [Bug-glpk] unexpected ending at 4.xx%
Date: Mon, 04 Jun 2012 23:55:23 +0400

> Here are some files :
> - a data file pmedian2.dat
> - a model file  contraintesmax.mod
> - the end of the log file of glpk executing contraintesmax.mod on
> pmedian2.dat
> 
> 
> If this is really a bug I hope it can help improve glpk.
> 
> 
> I am not blocked in any way and do not expect anything. 
> I am studying and taking a course with glpk.

Thank you for your bug report.

The bug appears in the time measuring routine, most probably because of
overflow of the timer. This bug is not related to the mip solver.

On which platform are you running glpk and how did you build it?

FYI: Your instance is hard for the glpk mip solver due to its size and
combinatorial structure. However, being pure 0-1 mip it can be solved
with the Minisat solver (--minisat) much more efficiently:

GLPSOL: GLPK LP/MIP Solver, v4.48
Parameter(s) specified in the command line:
 -m contraintesmax.mod -d pmedian2.dat --minisat --log log.txt
Reading model section from contraintesmax.mod...
47 lines were read
Reading data section from pmedian2.dat...
107 lines were read
Generating maxdepot...
Generating unseulsite...
Generating depotouvert...
Generating distanceTotale...
Model has been successfully generated
Will search for ANY feasible solution
Translating to CNF-SAT...
Original problem has 10102 rows, 10100 columns, and 40100 non-zeros
10000 covering inequalities
100 partitioning equalities
Solving CNF-SAT problem...
Instance has 15094 variables, 41027 clauses, and 94876 literals
==================================[MINISAT]===================================
| Conflicts |     ORIGINAL     |              LEARNT              |
Progress |
|           | Clauses Literals |   Limit Clauses Literals  Lit/Cl |
|
==============================================================================
|         0 |   41026    94875 |   13675       0        0     0.0 |
0.000 % |
==============================================================================
SATISFIABLE
Objective value =   4.963000000e+03
Time used:   0.1 secs
Memory used: 23.7 Mb (24900711 bytes)

 Modèle utilisant le plus de contraintes 

 Depots ouverts 
 2   3   4   5   6   7   10   11   12   13  

 Affectation des clients aux depots
 client 1 au depot 2 
[...]
 client 99 au depot 2 
 client 100 au depot 2 
Model has been successfully processed

You also may try to find a better solution by specifying the '--objbnd'
option.





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