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<p>Hi Ambros.</p>
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<p>Thanks for your reponse and sorry for answering late. I have "switched off" presolving by including no presolver plugins, hence I only got the presolving code from the propagators and constraint handlers. That seems to work properly. I started to include
one presolver plugin after the other and there seems to be a problem with "domcol". It fixed a lot of variables and afterwards my problem is reported to be unbounded. I did not test all presolver plugins yet, but I will try to test all of them by the end of
this week. Any idea concerning "domcol"?</p>
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Regards
<div>Christian<br>
<br>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>Von:</b> Scip <scip-bounces@zib.de> im Auftrag von Ambros Gleixner <gleixner@zib.de><br>
<b>Gesendet:</b> Mittwoch, 13. Januar 2021 21:15<br>
<b>An:</b> scip@zib.de<br>
<b>Betreff:</b> Re: [SCIP] After stopping pricing and doing restart, model is becoming unbounded during presolve?</font>
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<div class="PlainText">Hi Christian,<br>
<br>
Strange indeed. Have you tried to turn off presolving? Does it still <br>
happen? Have you tried to successively activate individual presolvers <br>
to see when it starts failing?<br>
<br>
Best,<br>
Ambros<br>
<br>
<br>
Am 04.01.21 um 17:10 schrieb Franzen, Christian:<br>
> Hi Scip Team.<br>
> <br>
> <br>
> Thanks to the help of Gregor, I managed to make SCIP stop pricing after <br>
> some iterations and doing a restart on the reduced master without <br>
> pricing. Unfortunately, I am facing some really strang behaviour. <br>
> Sometime it happens, that my model (for that I already have found a <br>
> feasible solution), is reported to be unbound. I wrote the corresponding <br>
> LP files before and after presolving to disk and I see that some <br>
> variable bounds vanished, which seems to be the reason for the <br>
> unboundness. Furthermore, some of the objective coefficients changed <br>
> their sign. Any ideas how or why that is happening during presolving?<br>
> <br>
> <br>
> Regards<br>
> <br>
> Christian<br>
> <br>
> <br>
> P.S.: I attach the SCIP log for one of these runs.<br>
> <br>
> <br>
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> Scip mailing list<br>
> Scip@zib.de<br>
> <a href="https://listserv.zib.de/mailman/listinfo/scip">https://listserv.zib.de/mailman/listinfo/scip</a><br>
> <br>
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