[Cbc] [CBC] Preprocess causing infeasibility

[Haroldo Gambini Santos]

Hi Marco,

I found out that the problem is related to a presolving procedure which 
tries to fix bounds using dual information.

A /quick and dirty/ fix is to change in

Osi/src/OsiPresolve.cpp   line    988

if (dual) {
to
if ((dual)&&0) {

to temporarily disable this processing...

Hoping that a better fix comes soon,

Cheers,

Haroldo

On 28-09-2015 06:22, mg wrote:
> Hi all,
> I've found a case where preprocess says the problem is infeasible, but 
> if I turn preprocess off, the problem is correctly solved.
>
> Attached you can find the LP file (m3.lp). To reproduce the problem 
> you can use the following code (I use callCbc):
>
> OsiClpSolverInterface solver;
> CbcModel model(solver);
> model.solver()->readLp("m3.lp");
> std::string args("-heur off -cuts off -solve");
> // using these arguments instead it works
> // std::string args("-heur off -cuts off -preprocess off -solve");
> callCbc(args, model);
>
> The problem happens in both 2.9.5 releaseand 2.9.6 release versions.
>
> Thanks in advance,
> Marco
>
>
> _______________________________________________
> Cbc mailing list
> Cbc at list.coin-or.org
> http://list.coin-or.org/mailman/listinfo/cbc

-- 
==================================================
Haroldo Gambini Santos
D.Sc, Computer Science
Universidade Federal de Ouro Preto
http://www.decom.ufop.br/haroldo/

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.coin-or.org/pipermail/cbc/attachments/20150928/f918d3e4/attachment.html>