<div dir="ltr">O<font face="monospace, monospace">k, so if I understood correctly you've only changed <span style="font-size:12.8px">CoinPresolveDoubleton.cpp, am I right ?</span></font><div><span style="font-size:12.8px"><font face="monospace, monospace"><br></font></span></div><div><span style="font-size:12.8px"><font face="monospace, monospace">Thanks a lot for the quick fix !</font></span></div><div><span style="font-size:12.8px"><font face="monospace, monospace"><br></font></span></div><div><span style="font-size:12.8px"><font face="monospace, monospace">Marco</font></span></div></div><div class="gmail_extra"><br><div class="gmail_quote">2015-09-29 15:41 GMT+02:00 John Forrest <span dir="ltr"><<a href="mailto:john.forrest@fastercoin.com" target="_blank">john.forrest@fastercoin.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>Marco,<br>
<br>
Should be fixed.<br>
<br>
The dual code correctly thought it should push a variable all the
way to its upper bound. Unhappily the upper bound was 1.3. Then
a later part of presolve worked out that that was infeasible for
an integer variable.<br>
<br>
The error occurred in CoinPresolveDoubleton which changed bounds
from 0,infinity to 0,1.3 without checking whether it was integer.
I have corrected code so bounds would be 0,1.<span class="HOEnZb"><font color="#888888"><br>
<br>
John Forrest</font></span><div><div class="h5"><br>
<br>
On 28/09/15 23:46, Haroldo Gambini Santos wrote:<br>
</div></div></div><div><div class="h5">
<blockquote type="cite">
Hi Marco,<br>
<br>
I found out that the problem is related to a presolving procedure
which tries to fix bounds using dual information.<br>
<br>
A <i>quick and dirty</i> fix is to change in<br>
<br>
Osi/src/OsiPresolve.cpp line 988<br>
<br>
if (dual) {<br>
to <br>
if ((dual)&&0) {<br>
<br>
to temporarily disable this processing...<br>
<br>
Hoping that a better fix comes soon,<br>
<br>
Cheers,<br>
<br>
Haroldo<br>
<br>
<div>On 28-09-2015 06:22, mg wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr"><font face="monospace, monospace">Hi all,</font>
<div><font face="monospace, monospace">I've found a case where
preprocess says the problem is infeasible, but if I turn
preprocess off, the problem is correctly solved.</font></div>
<div><font face="monospace, monospace"><br>
</font></div>
<div><span style="font-size:12.8px"><font face="monospace,
monospace">Attached you can find the LP file (m3.lp). To
reproduce the problem you can use the following code (I
use callCbc):</font></span></div>
<div><span style="font-size:12.8px"><br>
</span></div>
<div><span style="font-size:12.8px"><font face="monospace,
monospace"><span style="white-space:pre-wrap"> </span>OsiClpSolverInterface
solver;</font></span></div>
<div><span style="font-size:12.8px"><font face="monospace,
monospace"><span style="white-space:pre-wrap"> </span>CbcModel
model(solver);</font></span></div>
<div><span style="font-size:12.8px"><font face="monospace,
monospace"><span style="white-space:pre-wrap"> </span>model.solver()->readLp("m3.lp");</font></span></div>
<div><span style="font-size:12.8px"><font face="monospace,
monospace"><span style="white-space:pre-wrap"> </span>std::string
args("-heur off -cuts off -solve");</font></span></div>
<div><span style="font-size:12.8px"><font face="monospace,
monospace"><span style="white-space:pre-wrap"> </span>//
using these arguments instead it works</font></span></div>
<div><span style="font-size:12.8px"><font face="monospace,
monospace"><span style="white-space:pre-wrap"> </span>//
std::string args("-heur off -cuts off -preprocess off
-solve"); </font></span></div>
<div><span style="font-size:12.8px"><font face="monospace,
monospace"><span style="white-space:pre-wrap"> </span>callCbc(args,
model); </font></span><br>
</div>
<div><span style="font-size:12.8px"><font face="monospace,
monospace"><br>
</font></span></div>
<div><font face="monospace, monospace"><span style="font-size:12.8px">The problem happens in both
2.9.5 </span></font><span style="font-family:monospace,monospace;font-size:12.8px">release</span><span style="font-family:monospace,monospace;font-size:12.8px"> </span><span style="font-size:12.8px;font-family:monospace,monospace">and
2.9.6 release versions.</span></div>
<div><span style="font-size:12.8px;font-family:monospace,monospace"><br>
</span></div>
<div><span style="font-size:12.8px;font-family:monospace,monospace">Thanks
in advance,</span></div>
<div><span style="font-size:12.8px;font-family:monospace,monospace">Marco</span></div>
</div>
<br>
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<br>
<pre cols="72">--
==================================================
Haroldo Gambini Santos
D.Sc, Computer Science
Universidade Federal de Ouro Preto
<a href="http://www.decom.ufop.br/haroldo/" target="_blank">http://www.decom.ufop.br/haroldo/</a></pre>
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