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<p>Hi,</p>
<p>thank you both, Haroldo and David, for your suggestions. I am
aware of the possibility of adding slack variables to find the
problematic constraints. However, I just recently created a
reformulation of the model to get rid of a large number of slack
variables and thereby drastically decrease solution time. This
brought with it the aforementioned problem of infeasibilities.</p>
<p>As it seems to be impossible to find the problematic constraints
with CBC without using slack variables, I have now added
preprocessing to my model which should hopefully catch all
possible problems. I was hoping to avoid this, as I will have to
manually adjust it together with the model, but it seems to me
this is the most sensible option for now.<br>
</p>
<p>Thanks again and best regards,</p>
<p>Christopher<br>
</p>
<br>
<div class="moz-cite-prefix">On 2016-05-30 16:24, David Ibarra Gómez
wrote:<br>
</div>
<blockquote cite="mid:DUB115-W112EE5E506397804809C1CDA3450@phx.gbl"
type="cite">
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<div dir="ltr">I do not know an automatic way of doing that.
<div><br>
</div>
<div>I usually build a second problem (to be solved if the
original its infeasible) full of slacks on each constraint
with very high cost on the objective function. The non-zero
slacks gives clues of which is the problem. </div>
<div><br>
</div>
<div>Some times I run several problems changing the cost of the
slacks if there are too much non zero.<br>
<br>
I know it's not exactly what you looked at, but it has work
for me on real problems. User found very useful to have a clue
about what's wrong when the problem it's infeaseble and they
are changing input data.
<div><br>
</div>
<div>Kind regards.</div>
<div><br>
</div>
<div>David Ibarra </div>
<div><br>
</div>
<div><br>
<br>
<br>
<div>> To: <a class="moz-txt-link-abbreviated" href="mailto:cbc@list.coin-or.org">cbc@list.coin-or.org</a><br>
> From: <a class="moz-txt-link-abbreviated" href="mailto:christopher.gross@unikat.uni-augsburg.de">christopher.gross@unikat.uni-augsburg.de</a><br>
> Date: Mon, 30 May 2016 15:47:56 +0200<br>
> Subject: [Cbc] How to debug infeasible problems<br>
> <br>
> Hi,<br>
> <br>
> I am using CBC in a software that generates models
based on user input. <br>
> Sometimes, users input invalid data leading to an
infeasible model. As <br>
> the amount of data they enter is not very small, it
is often hard to see <br>
> at a glance which data exactly causes the problem.<br>
> <br>
> Is it possible to configure CBC to output why a
problem is infeasible? <br>
> It would be great if it could give the line name
where the conflict <br>
> occurs, similar to what CPLEX does. I had a look
around the config <br>
> options, but could not find how to turn this on. Am I
missing something <br>
> or is this feature not available?<br>
> <br>
> Thanks and regards,<br>
> <br>
> Christopher<br>
> -- <br>
> Christopher Gross, M.Sc.<br>
> <br>
> Lehrstuhl für Health Care Operations/Health
Information Management<br>
> <br>
> Universitäres Zentrum für Gesundheitswissenschaften
am Klinikum Augsburg<br>
> (UNIKA-T), Neusässer Straße 47, 86156 Augsburg;<br>
> <br>
> Wirtschaftswissenschaftliche Fakultät, Universität
Augsburg,<br>
> Universitätsstraße 16, 86159 Augsburg<br>
> <br>
> <br>
> Tel.: +49 821 598-6454<br>
> <br>
> E-Mail: <a class="moz-txt-link-abbreviated" href="mailto:christopher.gross@unikat.uni-augsburg.de">christopher.gross@unikat.uni-augsburg.de</a><br>
> Web: <a class="moz-txt-link-freetext" href="http://www.wiwi.uni-augsburg.de/bwl/brunner/">http://www.wiwi.uni-augsburg.de/bwl/brunner/</a><br>
> _______________________________________________<br>
> Cbc mailing list<br>
> <a class="moz-txt-link-abbreviated" href="mailto:Cbc@list.coin-or.org">Cbc@list.coin-or.org</a><br>
> <a class="moz-txt-link-freetext" href="http://list.coin-or.org/mailman/listinfo/cbc">http://list.coin-or.org/mailman/listinfo/cbc</a><br>
</div>
</div>
</div>
</div>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Christopher Gross, M.Sc.
Lehrstuhl für Health Care Operations/Health Information Management
Universitäres Zentrum für Gesundheitswissenschaften am Klinikum Augsburg
(UNIKA-T), Neusässer Straße 47, 86156 Augsburg;
Wirtschaftswissenschaftliche Fakultät, Universität Augsburg,
Universitätsstraße 16, 86159 Augsburg
Tel.: +49 821 598-6452
E-Mail: <a class="moz-txt-link-abbreviated" href="mailto:christopher.gross@unikat.uni-augsburg.de">christopher.gross@unikat.uni-augsburg.de</a>
Web: <a class="moz-txt-link-freetext" href="http://www.unika-t.de/">http://www.unika-t.de/</a></pre>
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