<div dir="ltr"><div>Hi,<br><br></div><div>Thanks for the fast reply! I followed what you said, but I guess I'm doing something wrong, can you help me to figure it out?<br><br></div><div>So
first I enclosed the part of the code that I want to compute the lower
bounds in SCIPstartProbing(scip) and SCIPendProbing(scip).<br><br></div><div>Then
I call SCIPnewProbingNode(scip), create the constraint1 and add it with
SCIPaddRowProbing(scip, constraint1). I then solve the probing node
with SCIPsolveProbingLP(scip, -1, &lperror, &cutoff), get the
lower bound with SCIPgetLPObjval(scip) and got back to the parent with
SCIPbacktrackProbing(scip, 1).<br><br></div><div>This same process is then repeated imposing constraint2 in the problem.<br><br></div><div>Can
you tell me if this is the right way to do it? The code is not working
as it was before adding the branching rule and I'm having some difficulties in
understanding how to use the probing mode correctly.<br><br></div><div>Thanks again,<br></div><div>Matheus</div><br></div><div class="gmail_extra"><br><div class="gmail_quote">2018-03-20 5:52 GMT-03:00 Gregor Hendel <span dir="ltr"><<a href="mailto:hendel@zib.de" target="_blank">hendel@zib.de</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
Dear Matheus,<br>
<br>
this sounds like an application of the SCIP probing mode, which
allows to explore some tentative children before branching. Please
have a look at the documentation of the probing mode:<br>
<br>
<a class="m_3923750445048037240moz-txt-link-freetext" href="http://scip.zib.de/doc-5.0.1/html/group__PublicProbingMethods.php" target="_blank">http://scip.zib.de/doc-5.0.1/<wbr>html/group__<wbr>PublicProbingMethods.php</a><br>
<br>
Probing mode supports local constraints at the tentative node, and
solve the corresponding LP relaxation.<br>
<br>
You can then retrieve the LP solution objective using
SCIPgetLPObjval(), see also<br>
<br>
<a class="m_3923750445048037240moz-txt-link-freetext" href="http://scip.zib.de/doc-5.0.1/html/group__PublicLPMethods.php" target="_blank">http://scip.zib.de/doc-5.0.1/<wbr>html/group__PublicLPMethods.<wbr>php</a><br>
<br>
for further information.<br>
<br>
Happy probing,<br>
Gregor<div><div class="h5"><br>
<br>
<br>
<div class="m_3923750445048037240moz-cite-prefix">Am 19.03.2018 um 21:45 schrieb Matheus
Ota:<br>
</div>
</div></div><blockquote type="cite"><div><div class="h5">
<div dir="ltr">
<div>
<div>
<div>Hi,<br>
<br>
</div>
Im trying to use SCIP to implement a Branch-Cut-and-Price
for the VRP. For now Im focusing only on the Branch-and-Cut
part, using the CVRPSEP package (<a href="http://econ.au.dk/research/researcher-websites/jens-lysgaard/cvrpsep/" target="_blank">http://econ.au.dk/research/<wbr>researcher-websites/jens-<wbr>lysgaard/cvrpsep/</a>).
I already added the cuts and my program is able to solve
some simple instances, in order to increase its performance
I need to implement custom branching rules. <br>
<br>
</div>
The branching rule works this way: it first select a few
subsets of the set of vertexes in the graph and impose a few
constraints on them. It then computes the lower bound (solving
the relaxation) for each child node and uses these values to
choose the node to branch on. Could you please give me some
information about of how I can get the lower bound on the
branching rule callback? Or maybe a better way of doing this
or something similar?<br>
<br>
</div>
<div>Thanks,<br>
</div>
<div>Matheus <br>
</div>
</div>
<br>
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