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<div class="moz-cite-prefix">Dear Xiangyong,<br>
<br>
no, there is no specific documentation about the implementation of
a Lagrangian relaxation in SCIP, but the general documentation
about relaxation handlers should be a good point to start with.<br>
<br>
Best,<br>
Gerald<br>
<br>
Am 19.08.2014 um 16:00 schrieb Xiangyong Li:<br>
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<div><span></span> Dear Dr. Gamrath,</div>
<div><br>
</div>
<div>Thanks. Is there any reference regarding implementation of
Lagrangian relaxation based branch and bound in the SCIP? </div>
<div> </div>
Best regards,
<div><br>
</div>
<div><br>
</div>
<div>Xiangyong<br>
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<div><b>From:</b> <a moz-do-not-send="true"
href="mailto:gamrath@zib.de">Gerald Gamrath</a></div>
<div><b>Date:</b> 2014-08-19 18:26</div>
<div><b>To:</b> <a moz-do-not-send="true"
href="mailto:lixiangyong@163.com">lixiangyong@163.com</a>;
<a moz-do-not-send="true" href="mailto:scip@zib.de">scip</a></div>
<div><b>Subject:</b> Re: [Scip] how to implement
Lagrangian relaxation based branch-and-bound?</div>
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<div class="moz-cite-prefix">Dear Xiangyong,<br>
<br>
yes, you can use SCIP for that. You need to implement a
relaxation handler, see<br>
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://scip.zib.de/doc/html/RELAX.php">http://scip.zib.de/doc/html/RELAX.php</a><br>
<br>
Additionally, you can turn off LP solving by setting the
parameter "lp/solvefreq" to -1.<br>
<br>
Best,<br>
Gerald<br>
<br>
Am 19.08.2014 um 03:44 schrieb <a
moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:lixiangyong@163.com">lixiangyong@163.com</a>:<br>
</div>
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type="cite" style="margin-top: 0px;">
<div><span></span>
<p dir="ltr" style="font-size: 21px; margin-top: 0px;
margin-bottom: 0px;"> Dear all, </p>
<p dir="ltr" style="font-size: 21px; margin-top: 0px;
margin-bottom: 0px;"><br>
</p>
<p dir="ltr" style="margin-bottom: 0px; margin-top:
0px; font-size: 21px;">
I want to implement a Lagrangian relaxation based on branch-and
bound algorithm. That is,
at each node of the enumeration tree,
I do not solve LP relaxation,
but Lagrangian dual problem to determine a good lower bound and also
try to get an upper bound.
Also I have my own branching strategy. </p>
<p dir="ltr" style="margin-bottom: 0px; margin-top:
0px; font-size: 21px;"> </p>
<p dir="ltr" style="margin-bottom: 0px; margin-top:
0px; font-size: 21px;"> Can I use SCIP
as a framework to implement my algorithm? In other words, SCIP
takes charge of
most of the job and I only control the solving of Lagrangian Dual and branching. </p>
<p dir="ltr" style="margin-bottom: 0px; margin-top:
0px; font-size: 21px;"><span
style="background-color: window; line-height:
1.5;"><br>
</span></p>
<p dir="ltr" style="margin-bottom: 0px; margin-top:
0px; font-size: 21px;"><span
style="background-color: window; line-height:
1.5;">Is it possible to use solvecallback to solve a Lagrangian dual at each node and turn off solving the LP relaxation? Is there any way to pass this new lower bound to SCIP
and ask SCIP to control the search tree? </span></p>
<p dir="ltr" style="margin-bottom: 0px; margin-top:
0px; font-size: 21px;">
Is there any reference in the SCIP manual? </p>
<p dir="ltr" style="margin-bottom: 0px; margin-top:
0px; font-size: 21px;"> </p>
<p dir="ltr" style="margin-bottom: 0px; margin-top:
0px; font-size: 21px;">
Would you please give me some suggestions? Thanks.</p>
<p dir="ltr" style="margin-bottom: 0px; margin-top:
0px; font-size: 21px;"><br>
</p>
<p dir="ltr" style="margin-bottom: 0px; margin-top:
0px; font-size: 21px;"><br>
</p>
<p dir="ltr" style="margin-bottom: 0px; margin-top:
0px; font-size: 21px;">Xiangyong Li</p>
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