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<div class="moz-cite-prefix">Hi Alessia,<br>
<br>
can you send me logs (including statistics) for the two runs?<br>
<br>
One thing you can try is to set "lp/disablecutoff" to 0. Before
SCIP 3.1, the cutoff bound was always applied in the LP solver,
even if you do branch-and-price and will use the dual solution to
generate new columns. It is still a correct algorithm if you use
the dual values you get when the objective limit was reached, but
you will need to solve the LP from scratch afterwards. Especially
for large master LPs, this can be quite expensive, so that we
automatically disabled it now, but it is a sort of stabilization
and might pay off if your master LP is very easy to solve and
solving it from scratch doesn't hurt too much.<br>
<br>
Best,<br>
Gerald<br>
<br>
On 12.03.2014 15:59, Alessia Violin wrote:<br>
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Hello,<br>
<br>
I just passed to the new version of SCIP and tried to make a
couple of tests, the new version seems to be significantly slower
compared to the 3.0.1. <br>
<br>
I am using Cplex as the lp solver, and I had to compile with the
tags ZIMP=false READLINE=false ZLIB=false GMP=false (exactly as
the previous version, except for GMP).<br>
<br>
I have a Branch-and-Price code, with quite a few more features
(pricer, branching rule, heuristics, cuts). To make my code
working I just needed to change the functions
SCIP_DECL_PRICERREDCOST() and SCIPaddCut() adding the new
parameters. All the rest is exactly the same. The number of nodes
and columns generated is much bigger, and the dual bound is
converging very slowly. The time goes from less than a second to
some few hundred seconds.<br>
<br>
Do you have any insight of this behaviour? or anything in
particular I should check that is behaving differently in the new
version?<br>
<br>
Thanks in advance!<br>
<br>
best,<br>
<br>
Alessia<br>
<br>
<br>
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<pre class="moz-signature" cols="72">--
Alessia Violin
Service Graphes et Optimisation Mathématique (G.O.M.)
Université Libre de Bruxelles
C.P. 210/01
Boulevard du Triomphe
B-1050 BRUXELLES
Tel: 02 650 58 80 - Fax: 02 650 59 70
Email: <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:aviolin@ulb.ac.be">aviolin@ulb.ac.be</a>
Webpage: <a moz-do-not-send="true" class="moz-txt-link-freetext" href="http://homepages.ulb.ac.be/%7Eaviolin/">http://homepages.ulb.ac.be/~aviolin/</a></pre>
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