<html data-lt-installed="true">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body style="padding-bottom: 1px;">
<p>Hi Ambros,</p>
<p>thank you for looking into it! I tried your suggestion, but i
still encountered two problems:</p>
<p>1. Deactivating the pricer is not possible in the PROBLEM stage.
My workaround was to copy with pricing disabled and then include
and activate the pricer in the copied SCIP.<br>
2. Due to me copying with pricing disabled, SCIP marked all copied
constraints to not be modifiable. This led the copy to be
trivially solvable in presolving. Solution here was to iterate
through all my original constraints and applying their modifiable
tag to their copies.</p>
<p>So I think it would be very helpful to have a clean fix in a
future release :)</p>
<p>All the best,<br>
Alex</p>
<p>P.S: If anyone else stumbles upon the same problem and fixes it
in a similar way, don't forget to "SCIPcopyParamSettings" (or set
them to specific values for the copy) after including the pricer
in the copy if your pricer has parameters. <br>
</p>
<div class="moz-cite-prefix">On 04.08.23 09:57, Ambros Gleixner
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:a8786c51-96ff-7fee-d132-d5992ea4f882@zib.de">Hi Alex,
<br>
<br>
Sorry for the longer wait. You clearly identified a logical bug
here.
<br>
<br>
One workaround might be:
<br>
1. deactivate your pricer in the sourcescip by
SCIPdeactivatePricer()
<br>
2. copy (with enablepricing=TRUE)
<br>
3. activate your pricer again in the sourcescip
<br>
4. find pricer in the targetscip and activate it
<br>
<br>
Please let us know if that works or not. We will look into fixing
this cleanly in future versions.
<br>
<br>
Best,
<br>
Ambros
<br>
<br>
<br>
Am 24.07.2023 um 11:57 schrieb Alexander Helber:
<br>
<blockquote type="cite">Dear SCIP community,
<br>
<br>
I am working on a branch-and-price approach for a specific
problem and wanted to add a simple heuristic which solves the
same problem with some variables fixed. I implemented the
copying callbacks for my problem data and pricer, but now face
the problem that `SCIPcopy` throws an exception due to the SCIP
copy being in the wrong stage.
<br>
<br>
The SCIP copy is a freshly created instance and therefore the
INIT stage, as expected by `SCIPcopy` (see `scip_copy:2888` in
SCIP 8.0.2). But then the pricers are added and activated
(`set.c:911`), which is only possible in the PROBLEM stage
(`scip_pricer.c:380`). I can not find a use of `SCIPcopy` with
pricing enabled in the codebase of the SCIP Optimization Suite,
so it is unclear to me if I should do something different here.
I would greatly appreciate your help.
<br>
<br>
All the best
<br>
Alex
<br>
<br>
<br>
_______________________________________________
<br>
Scip mailing list
<br>
<a class="moz-txt-link-abbreviated" href="mailto:Scip@zib.de">Scip@zib.de</a>
<br>
<a class="moz-txt-link-freetext" href="https://listserv.zib.de/mailman/listinfo/scip">https://listserv.zib.de/mailman/listinfo/scip</a>
<br>
</blockquote>
_______________________________________________
<br>
Scip mailing list
<br>
<a class="moz-txt-link-abbreviated" href="mailto:Scip@zib.de">Scip@zib.de</a>
<br>
<a class="moz-txt-link-freetext" href="https://listserv.zib.de/mailman/listinfo/scip">https://listserv.zib.de/mailman/listinfo/scip</a>
<br>
</blockquote>
<pre class="moz-signature" cols="72">--
Alexander Helber
Research and Teaching Assistant
Chair of Operations Research
RWTH Aachen University
Kackertstrasse 7
52072 Aachen
Germany
Web: or.rwth-aachen.de
Mail: <a class="moz-txt-link-abbreviated" href="mailto:helber@or.rwth-aachen.de">helber@or.rwth-aachen.de</a></pre>
</body>
<lt-container></lt-container>
</html>