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Hello Lan,<br>
<br>
find the answers to your two questions inline.<br>
<br>
<div class="moz-cite-prefix">Am 10.10.19 um 01:40 schrieb Ngô Lan:<br>
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<p>Hi Gregor,</p>
<p><br>
</p>
<p>Thank you for your reply. It works now. Would it be possible
to add the deleted constraints again to scip? Ideally, when a
node is entered again, I would like to enable the constraint
instead of creating a new one. My code does not run yet so I
haven't had chance to test it.</p>
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As long as you do not release the constraint pointers (using
SCIPreleaseCons()), SCIP will not physically delete the constraint,
but only remove it from the problem, so that you can later add them
again. An explanation of the capture/release mechanism for variables
can be found here <a class="moz-txt-link-freetext" href="https://scip.zib.de/doc/html/OBJ.php">https://scip.zib.de/doc/html/OBJ.php</a>, the
explanation also applies to constraints.<br>
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<p>I also have another problem with the child nodes. So for
branching, I created a linear branching constraint and a
marker constraint from my constraints handler and added
them into a child node (sticking at node is true). However, in
subscip when I check in which branch I am at using <span>SCIPconsIsActive,
I get true even for the constraints that were not created in
this node. Do you have any idea where things might go wrong?</span></p>
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As far as I understand your approach, all constraints of the subscip
should be active, because at every node (of the main solving
process), you free the transformed problem of the subscip and then
you add exactly those constraints that reflect your current
branching decision. Are you using SCIPconsIsActive on the main
solving process constraints, or on the subscip constraints? For the
main SCIP, I expect that all branching constraints (there might be
several ones along the path from the root) are active, and the rest
is not active.<br>
<br>
Kind regards,<br>
Gregor<br>
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cite="mid:fa2f98ba0ff44cf6a513f4b3d6621037@aalto.fi">
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<p><span><br>
</span></p>
<p><span>Best,</span></p>
<p><span>Lan</span></p>
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<hr style="display:inline-block;width:98%" tabindex="-1">
<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt"
face="Calibri, sans-serif" color="#000000"><b>From:</b> Scip
<a class="moz-txt-link-rfc2396E" href="mailto:scip-bounces@zib.de"><scip-bounces@zib.de></a> on behalf of Gregor Hendel
<a class="moz-txt-link-rfc2396E" href="mailto:hendel@zib.de"><hendel@zib.de></a><br>
<b>Sent:</b> 09 October 2019 10:32:17<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:scip@zib.de">scip@zib.de</a><br>
<b>Subject:</b> Re: [SCIP] Using SCIPdisableCons in problem
creation stage</font>
<div> </div>
</div>
<div>Good morning Lan,<br>
<br>
how about using SCIPdelCons() instead of SCIPdisableCons()?<br>
<br>
Let me know if that works for you,<br>
Gregor<br>
<br>
<div class="moz-cite-prefix">Am 09.10.19 um 01:03 schrieb Ngô
Lan:<br>
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<p>Hi all,</p>
<p><br>
</p>
<p>I am solving a project scheduling problem using
branch-price-cut and I am having an issue with <span>SCIPdisableCons
function. So after each pricing iteration, I will not
release the subscip but only free the transformed
problem using SCIPfreetransform and modify the objective
function of the subscip in the next iteration. During
branching, in CONSACTIVE, I will create an additional
constraint for the subproblem depending on the branching
decision and in CONSDEACTIVE, I will disable the related
constraint using <span>SCIPdisableCons. However, I got
the error: <span>cannot call method
<SCIPdisableCons> in problem creation stage.
Do you know another function that can work? Or what
should I do differently?</span></span></span></p>
<p><span><span><span><br>
</span></span></span></p>
<p><span><span><span>Thank you for your time,</span></span></span></p>
<p><br>
</p>
<p>Best,</p>
<p>Lan</p>
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