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<div class="moz-cite-prefix">Dear Xiangyong,<br>
<br>
when using SCIPsetObjIntegral(), you do not need to call
SCIPinterruptSolve() yourself, but SCIP will stop because it knows
that optimality has been proven as soon as the primal bound is x
and the lower bound is greater than x - 1.<br>
Also the LP solving might be sped up, since a smaller cutoff bound
can be set (which is irrelevant for branch-and-price, however).<br>
Furthermore, also some plugins use this information to improve
their algorithms.<br>
<br>
Summing up: If you know that every solution will have an integer
value, you should tell SCIP about that. For branch-and-cut, SCIP
will automatically detect this, however, for branch-and-price, not
all variables are present, so it cannot be detected automatically.<br>
<br>
Best,<br>
Gerald<br>
<br>
Am 24.09.2014 um 02:32 schrieb <a class="moz-txt-link-abbreviated" href="mailto:lixiangyong@163.com">lixiangyong@163.com</a>:<br>
</div>
<blockquote cite="mid:2014092408320915414913@163.com" type="cite">
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<div><span></span>Dear Dr. <span style="font-size: 12pt;
line-height: 1.5; background-color: window;">Ambros,</span></div>
<div><span style="font-size: 12pt; line-height: 1.5;
background-color: window;"><br>
</span></div>
<div><span style="font-size: 12pt; line-height: 1.5;
background-color: window;">I want to know the </span><span
style="font-size: 12pt; line-height: 1.5; background-color:
window;">advantage of calling SCIPsetObjIntegral() if at the
beginning I </span><span style="font-size: 12pt; line-height:
1.5; background-color: window;">know any feasible solution
should have an integer objective value? Can</span><span
style="font-size: 12pt; line-height: 1.5; background-color:
window;"> it speed up the solving process?</span></div>
<div><span style="font-size: 12pt; line-height: 1.5;
background-color: window;"><br>
</span></div>
<div><span style="font-size: 12pt; line-height: 1.5;
background-color: window;">Thanks,</span></div>
<div><span style="font-size: 12pt; line-height: 1.5;
background-color: window;"><br>
</span></div>
<div><span style="font-size: 12pt; line-height: 1.5;
background-color: window;">Xiangyong Li</span></div>
<div><span style="font-size: 12pt; line-height: 1.5;
background-color: window;"><br>
</span></div>
<blockquote style="margin-top: 0px; margin-bottom: 0px;
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<div><b>From:</b> <a moz-do-not-send="true"
href="mailto:gleixner@zib.de">Ambros Gleixner</a></div>
<div><b>Date:</b> 2014-09-24 08:21</div>
<div><b>To:</b> <a moz-do-not-send="true"
href="mailto:scip@zib.de">scip</a>; <a
moz-do-not-send="true" href="mailto:lixiangyong@163.com">lixiangyong@163.com</a></div>
<div><b>Subject:</b> Re: [Scip] How to terminate SCIP
earlier?</div>
</div>
</div>
<div>
<div>Dear Xiangyong,</div>
<div> </div>
<div> </div>
<div>Am 24.09.2014 02:08, schrieb <a class="moz-txt-link-abbreviated" href="mailto:lixiangyong@163.com">lixiangyong@163.com</a>:</div>
<div>> Dear Dr. Gerald,</div>
<div>></div>
<div>> Thanks, I have used SCIPinterruptSolve() to
terminate my solving</div>
<div>> process since I know the current incumbent is the
optimal solution.</div>
<div>></div>
<div>> BTW, can you tell me the advantage of calling
SCIPsetObjIntegral() if I</div>
<div>> know any feasible solution should have an integer
objective value? Can</div>
<div>> it speed up the solving process?</div>
<div> </div>
<div>Yes. If (in minimization) the primal bound is x and the
lower bound is </div>
<div>greater than x - 1, the solution process can be stopped
already.</div>
<div> </div>
<div>Best regards,</div>
<div>Ambros</div>
<div> </div>
<div> </div>
<div>></div>
<div>></div>
<div>> Thanks,</div>
<div>></div>
<div>></div>
<div>> Xiangyong</div>
<div>></div>
<div>> *From:* Gerald Gamrath
<a class="moz-txt-link-rfc2396E" href="mailto:gamrath@zib.de"><mailto:gamrath@zib.de></a></div>
<div>> *Date:* 2014-09-23 17:16</div>
<div>> *To:* <a class="moz-txt-link-abbreviated" href="mailto:lixiangyong@163.com">lixiangyong@163.com</a>
<a class="moz-txt-link-rfc2396E" href="mailto:lixiangyong@163.com"><mailto:lixiangyong@163.com></a>; scip</div>
<div>> <a class="moz-txt-link-rfc2396E" href="mailto:scip@zib.de"><mailto:scip@zib.de></a></div>
<div>> *Subject:* Re: [Scip] How to terminate SCIP
earlier?</div>
<div>> Dear Xiangyong Li,</div>
<div>></div>
<div>> if you know that every feasible solution will
have an integer</div>
<div>> objective value and therefore want to stop the
solving process when</div>
<div>> the dualbound is larger than primalbound - 1,
you can just inform</div>
<div>> SCIP that this is the case by calling
SCIPsetObjIntegral().</div>
<div>></div>
<div>> Otherwise, you can call SCIPinterruptSolve() to
stop the solving</div>
<div>> process, but SCIP will then print that it was
interrupted, not that</div>
<div>> it was solved to optimality.</div>
<div>></div>
<div>> Best,</div>
<div>> Gerald</div>
<div>></div>
<div>> Am 23.09.2014 um 10:02 schrieb
<a class="moz-txt-link-abbreviated" href="mailto:lixiangyong@163.com">lixiangyong@163.com</a>:</div>
<div>>> Dear all,</div>
<div>>></div>
<div>>> I am using SCIP to implement my branch and
price algorithm.</div>
<div>>> Now I want to terminate the SCIP earlier
since I can judge the</div>
<div>>> problem has been optimally solved when some
condition is satisfied.</div>
<div>>> Suppose UB and LB be the objective value of
best incumbent and the</div>
<div>>> best remaining node in the branch and bound
tree.</div>
<div>>> For my instances considered, SCIP has
optimally solved one</div>
<div>>> instance if UB-LB < 1.</div>
<div>>></div>
<div>>> Can you tell me how to set the earlier
termination condition in SCIP?</div>
<div>>></div>
<div>>> Thanks,</div>
<div>>></div>
<div>>></div>
<div>>> Xiangyong Li</div>
<div>>></div>
<div>>></div>
<div>>></div>
<div>>></div>
<div>>>
_______________________________________________</div>
<div>>> Scip mailing list</div>
<div>>> <a class="moz-txt-link-abbreviated" href="mailto:Scip@zib.de">Scip@zib.de</a></div>
<div>>> <a class="moz-txt-link-freetext" href="http://listserv.zib.de/mailman/listinfo/scip">http://listserv.zib.de/mailman/listinfo/scip</a></div>
<div>></div>
<div>></div>
<div>></div>
<div>> _______________________________________________</div>
<div>> Scip mailing list</div>
<div>> <a class="moz-txt-link-abbreviated" href="mailto:Scip@zib.de">Scip@zib.de</a></div>
<div>> <a class="moz-txt-link-freetext" href="http://listserv.zib.de/mailman/listinfo/scip">http://listserv.zib.de/mailman/listinfo/scip</a></div>
<div>></div>
<div> </div>
<div>-- </div>
<div>____________________________________________________________</div>
<div>Ambros M. Gleixner</div>
<div>Zuse Institute Berlin - Matheon - Berlin Mathematical
School</div>
<div><a class="moz-txt-link-freetext" href="http://www.zib.de/gleixner">http://www.zib.de/gleixner</a></div>
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<pre wrap="">_______________________________________________
Scip mailing list
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