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<div class="moz-cite-prefix">Marco,<br>
<br>
Yes - I don't think other presolve functions change bounds in same
way.<br>
<br>
John<br>
<br>
On 29/09/15 14:57, mg wrote:<br>
</div>
<blockquote
cite="mid:CAOayR=YqZtTbi5hmSU+fsp08Nj9h4uA3pzOrk0=UQNDWOqypKA@mail.gmail.com"
type="cite">
<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 moz-do-not-send="true"
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 moz-do-not-send="true" href="http://www.decom.ufop.br/haroldo/" target="_blank">http://www.decom.ufop.br/haroldo/</a></pre>
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