<div dir="ltr"><div>John,</div><div>as Yves mentioned, twomir also seems to give some trouble. In these situations it's hard to put the blame on a single generator: most likely, it is a combination of things. So I'm not too surprised that swapping GMI for Gomory is not enough.</div><div><br></div><div>But I'm glad to hear that using CglGMI only seems to work on this problem and does not give the same numerical troubles!</div><div><br></div><div>Giacomo<br><div><br></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Mar 4, 2015 at 9:47 PM, John Forrest <span dir="ltr"><<a href="mailto:john.forrest@fastercoin.com" target="_blank">john.forrest@fastercoin.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>Giacomo,<br>
<br>
<br>
I tried swapping GMI for Gomory and the same thing happened.<br>
<br>
It just seems to be errors building up, especially with general
integer variables.<span class="HOEnZb"><font color="#888888"><br>
<br>
John</font></span><div><div class="h5"><br>
On 04/03/15 13:30, Giacomo Nannicini wrote:<br>
</div></div></div><div><div class="h5">
<blockquote type="cite">
<div dir="ltr">Hi Yves,
<div>did you try the CglGMI generator? You may want to see if
using CglGMI instead of CglGomory helps. In my experience, the
cuts from CglGMI are less prone to numerical errors: in fact,
that's the reason the generator was developed. See <a href="http://link.springer.com/article/10.1007%2Fs12532-013-0057-4" target="_blank">http://link.springer.com/article/10.1007%2Fs12532-013-0057-4</a></div>
<div><br>
</div>
<div>Giacomo</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, Mar 4, 2015 at 7:06 PM, Yves
Touchard <span dir="ltr"><<a href="mailto:ytouch@dxo.com" target="_blank">ytouch@dxo.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<small>Hello,<br>
<br>
Switching off the twomir cuts makes also the problem
feasible.<br>
<br>
Cheers<span><font color="#888888"><br>
<br>
Yves<br>
</font></span></small><br>
<div><span><br>
-------- Message transféré --------
<table border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<th align="RIGHT" nowrap valign="BASELINE">Sujet : </th>
<td>Gomory or not Gomory, that is the question.</td>
</tr>
<tr>
<th align="RIGHT" nowrap valign="BASELINE">Date : </th>
<td>Tue, 03 Mar 2015 20:03:03 +0100</td>
</tr>
<tr>
<th align="RIGHT" nowrap valign="BASELINE">De : </th>
<td>Yves Touchard <a href="mailto:yves.touchard@sfr.fr" target="_blank">
<yves.touchard@sfr.fr></a></td>
</tr>
<tr>
<th align="RIGHT" nowrap valign="BASELINE">Pour : </th>
<td><a href="mailto:cbc@list.coin-or.org" target="_blank">cbc@list.coin-or.org</a></td>
</tr>
</tbody>
</table>
<br>
<br>
</span>
<div>
<div><font size="-1">Hello,<br>
<br>
You will find here (</font><font size="-1"><font size="-1"><a href="https://www.dropbox.com/s/ayo93hi4togpc9m/noGom.lp?dl=0" target="_blank">https://www.dropbox.com/s/ayo93hi4togpc9m/noGom.lp?dl=0</a></font>)
a constraint file for which cbc founds a solution
when Gomory cuts are removed or for specific
cutlength values.<br>
<br>
In other words, the following command leads to an
infeasible problem:<br>
<i>/soft/cbc-trunk-2149/bin/cbc noGom.lp branch
printingOptions normal solution noGom.sol</i><br>
<br>
and with the following commands, cbc claims that
there is a solution:<br>
</font><font size="-1"><font size="-1"><i>/soft/cbc-trunk-2149/bin/cbc
noGom.lp gomory off branch printingOptions
normal solution noGom.sol</i></font><br>
</font><font size="-1"><font size="-1"><i>/soft/cbc-trunk-2149/bin/cbc
noGom.lp cutlength xx branch printingOptions
normal solution noGom.sol</i></font> (with xx
equal to -1, 0, 10, 20... and different from
30...)<br>
<br>
Since our problems are dynamically generated, it
is very painful to try to solve them with
different options, hoping that the right set is in
the list.<br>
<br>
</font><font size="-1">So, is there a way to find
this set of options.<br>
Or could you explain what are the rows that are
difficult for cbc.<br>
And, does the change of the continuous variables
into integer variables help? (for our problems, it
makes sense).<br>
<br>
Thanks and regards<br>
<br>
Yves<br>
</font><br>
</div>
</div>
</div>
<br>
<span>
<br>
<font color="Black" face="Arial">------------------------------------------------------------------------------<br>
This message and any attachments (the "message") are
confidential and intended solely for the addressee(s).
Any unauthorized use or dissemination is prohibited.
E-mails are susceptible to alteration. Neither DxO
Labs nor any of its subsidiaries or affiliates shall
be liable for the message if altered, changed or
falsified.<br>
Ce message et toutes les pièces jointes (ci-après le
"message") sont confidentiels et établis à l'intention
exclusive de ses destinataires. Toute utilisation ou
diffusion non autorisé est interdite. Tout message
électronique est susceptible d'altération. DxO Labs et
ses filiales déclinent toute responsabilité au titre
de ce message s'il a été altéré, modifié ou falsifié.<br>
</font>
</span></div>
<br>
_______________________________________________<br>
Cbc mailing list<br>
<a href="mailto:Cbc@list.coin-or.org" target="_blank">Cbc@list.coin-or.org</a><br>
<a href="http://list.coin-or.org/mailman/listinfo/cbc" target="_blank">http://list.coin-or.org/mailman/listinfo/cbc</a><br>
<br>
</blockquote>
</div>
<br>
</div>
<br>
<fieldset></fieldset>
<br>
<pre>_______________________________________________
Cbc mailing list
<a href="mailto:Cbc@list.coin-or.org" target="_blank">Cbc@list.coin-or.org</a>
<a href="http://list.coin-or.org/mailman/listinfo/cbc" target="_blank">http://list.coin-or.org/mailman/listinfo/cbc</a>
</pre>
</blockquote>
<br>
</div></div></div>
<br>_______________________________________________<br>
Cbc mailing list<br>
<a href="mailto:Cbc@list.coin-or.org">Cbc@list.coin-or.org</a><br>
<a href="http://list.coin-or.org/mailman/listinfo/cbc" target="_blank">http://list.coin-or.org/mailman/listinfo/cbc</a><br>
<br></blockquote></div><br></div>