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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hi –<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">We have a heuristic Optimization Engine heavily randomized (using Mercenne Random Generator BTW). We produce stabile/consistent results even for runs lasting
several weeks on a machine heavily threaded with a large number of simultaneous optimization runs. And with thousands of billions of iterations.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">So in our experience, in practice, optimization runs are 100% stable/identical.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Note, however, that random generators may/should be initialized and the generators may also contain internal state data. So we have to be very careful to shut
down an application (i.e. executable) completely before a new run in order to obtain identical results in next run.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">And any timing issues will of course influence, e.g. things like ‘abort after 5 minutes of optimization’. The result here will of course depend on total load
on machine, temperature of the CPU which impact the current GHz, etc.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="NO-BOK" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:green">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="NO-BOK" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:green">Bjørn Sigurd<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="NO-BOK" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:green">_________________________________<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="NO-BOK" style="font-size:8.0pt;font-family:Consolas;color:green">Bjørn Sigurd Benestad Johansen<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Consolas;color:green">Product Manager<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Consolas;color:green">Spider Solutions AS<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Consolas;color:green">Tlf +47 41 21 44 57<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Consolas;color:green"><a href="mailto:bjorn.sigurd.johansen@SpiderSolutions.no"><span style="color:green">bjorn.sigurd.johansen@SpiderSolutions.no</span></a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Consolas;color:green"><a href="http://www.spidersolutions.no/"><span style="color:green">www.SpiderSolutions.no</span></a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext"> Cbc [mailto:cbc-bounces@coin-or.org]
<b>On Behalf Of </b>Alexis<br>
<b>Sent:</b> Thursday, August 11, 2016 4:57 PM<br>
<b>To:</b> cbc@list.coin-or.org; Alexis <aguigue@softree.com>; David Mills <dmills@softree.com>; Craig Speirs <cspeirs@softree.com><br>
<b>Subject:</b> [Cbc] CBC deterministic<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p>Hi<o:p></o:p></p>
<p>I am just curious to know how ''deterministic'' CBC is. I know this question has been raised a few times in this forum i.e.<o:p></o:p></p>
<p><a href="http://list.coin-or.org/pipermail/cbc/2016-February/001891.html">http://list.coin-or.org/pipermail/cbc/2016-February/001891.html</a><o:p></o:p></p>
<p><a href="http://list.coin-or.org/pipermail/cbc/2015-January/001580.html">http://list.coin-or.org/pipermail/cbc/2015-January/001580.html</a><o:p></o:p></p>
<p>I have embedded CBC in my own application. In the case where I impose an integrality gap (e.g. 20%), I have had my program stopping and returning with different final optimality gaps (e.g. 12% and 19%). It is actually a little difficult to reproduce. I am
wondering whether this could come from the fact that I have (re) implemented the optimality gap stopping condition (with others actually) in the callback<o:p></o:p></p>
<p>CbcEventHandler::CbcAction myCbcEventHandler::event(CbcEvent whichEvent)<br>
{<o:p></o:p></p>
<p>...<br>
if (dIntGapCalc < dIntGapRef) {<o:p></o:p></p>
<p> ...<o:p></o:p></p>
<p> return stop;<br>
}<o:p></o:p></p>
<p> ...<o:p></o:p></p>
<p> }<o:p></o:p></p>
<p>....<o:p></o:p></p>
<p>}<o:p></o:p></p>
<p>Thanks in advance<o:p></o:p></p>
<p><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">-- <br>
Alexis Guigue, E.I.T., B.Eng., M.A.Sc., Ph.D. <br>
Software Engineer/Research Engineer <br>
604-519-6222, ext. 107 <br>
<br>
<a href="http://www.softree.com">Softree Technical Systems Inc.</a> <br>
Engineering an Easier Way <o:p></o:p></p>
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