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Hi Christian,<br>
<br>
It's hard to say where the problem is. Also your logfile looks
really strange.<br>
<br>
If you like, you can send me the lp-file and I will have a closer
look at this situation. Please also tell me which version of scip
you use, so that I can reproduce it.<br>
<br>
Best regards,<br>
Katrin<br>
<br>
<div class="moz-cite-prefix">Am 20.01.21 um 09:31 schrieb Franzen,
Christian:<br>
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<p>Hi Ambros.</p>
<p><br>
</p>
<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
style="font-size:11pt" face="Calibri, sans-serif"
color="#000000"><b>Von:</b> Scip
<a class="moz-txt-link-rfc2396E" href="mailto:scip-bounces@zib.de"><scip-bounces@zib.de></a> im Auftrag von Ambros
Gleixner <a class="moz-txt-link-rfc2396E" href="mailto:gleixner@zib.de"><gleixner@zib.de></a><br>
<b>Gesendet:</b> Mittwoch, 13. Januar 2021 21:15<br>
<b>An:</b> <a class="moz-txt-link-abbreviated" href="mailto:scip@zib.de">scip@zib.de</a><br>
<b>Betreff:</b> Re: [SCIP] After stopping pricing and
doing restart, model is becoming unbounded during
presolve?</font>
<div> </div>
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<font size="2"><span style="font-size:10pt;">
<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>
> _______________________________________________<br>
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<pre class="moz-quote-pre" wrap="">_______________________________________________
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<br>
<pre class="moz-signature" cols="72">--
Katrin Halbig, FAU Erlangen-Nürnberg, LS Wirtschaftsmathematik, Tel. +49 9131 85-67179</pre>
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