<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
Dear Tufan,<br>
<br>
we are actually making an effort to keep SCIP deterministic, so you
should see the same solution after every call on the same problem. A
time limit might lead to different results, but this does not seem
to be the case here.<br>
<br>
I tend to say you got "Pythoned" here.<br>
<br>
My best guess, as I have no other information how you invoke the
problem solve, is that you use dictionaries<br>
somewhere in the problem creation. Now, depending on the version,
Python's internal hashing is nondeterministic,<br>
see also <a moz-do-not-send="true"
href="https://stackoverflow.com/questions/14956313/why-is-dictionary-ordering-non-deterministic">here</a>.
The same would be true for Java, I suppose. If you loop over the
keys() of a dictionary, the order<br>
is different every time you run, effectively generating a different
permutation of your problem's columns and rows, which may affect the
performance of the MIP solver and also specific solution values may
be different between runs, but of course not the objective value of
an optimal solution.<br>
<br>
The link I posted contains a link to a solution to the problem using
a PYHASHSEED environment variable, which I haven't verified.<br>
<br>
Let us know if this is the source of, and solution to, your problem,<br>
Gregor<br>
<br>
<br>
<div class="moz-cite-prefix">Am 03.10.2018 um 13:09 schrieb Tufan
BAYDEMİR:<br>
</div>
<blockquote type="cite"
cite="mid:039afd9ca24f47369c235df71ab63ee9@OBSRVEXCH.OBASE.local">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered
medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri",sans-serif;
mso-fareast-language:EN-US;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#0563C1;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:#954F72;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;
mso-fareast-language:EN-US;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:70.85pt 70.85pt 70.85pt 70.85pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
<div class="WordSection1">
<p class="MsoNormal">I’m using pyscipopt interface within Python
to solve a MIP problem.
<o:p></o:p></p>
<p class="MsoNormal">I run the same code without making any
changes and obtain different optimal solutions.<o:p></o:p></p>
<p class="MsoNormal">The objective function value is the same
for all solutions. <o:p>
</o:p></p>
<p class="MsoNormal">But value of the decision variables are
always different ie. The program ganarates alternative optimal
solutions in each subsequent run.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">How can I insure that i get the same
solution?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Regards<o:p></o:p></p>
<p class="MsoNormal">Tufan<o:p></o:p></p>
</div>
<p><span
style="font-family:Verdana;font-size:14px;font-weight:bold;color:#224877;">o</span><span
style="font-family:Verdana;font-size:14px;font-weight:bold;color:#2B62A2;">b</span><span
style="font-family:Verdana;font-size:14px;font-weight:bold;color:#2D7EC0;">a</span><span
style="font-family:Verdana;font-size:14px;font-weight:bold;color:#3A94D0;">s</span><span
style="font-family:Verdana;font-size:14px;font-weight:bold;color:#46ABDF;">e</span><span
style="font-family:Verdana;font-size:12px;color:#1A3E72;">
Bilgisayar ve Danışmanlık Hizm. Tic. A.Ş.</span><br>
<span style="font-family:Verdana;font-size:11px;color:#1A3E72;">TEL:
+90216 527 30 00</span><br>
<span style="font-family:Verdana;font-size:11px;color:#1A3E72;">FAX:
+90216 527 31 11</span><br>
<span style="font-size:0;"><a href="http://www.obase.com"
target="_blank" moz-do-not-send="true"><img
src="http://www.obase.com/images/signature/home.png"
moz-do-not-send="true"></a>
<a href="https://www.facebook.com/obasesocial" target="_blank"
moz-do-not-send="true"><img
src="http://www.obase.com/images/signature/facebook.png"
moz-do-not-send="true"></a>
<a href="https://twitter.com/obasesocial" target="_blank"
moz-do-not-send="true"><img
src="http://www.obase.com/images/signature/twitter.png"
moz-do-not-send="true"></a>
<a href="https://tr.linkedin.com/in/obase" target="_blank"
moz-do-not-send="true"><img
src="http://www.obase.com/images/signature/linkedin.png"
moz-do-not-send="true"></a></span><br>
<a href="http://www.obase.com" target="_blank"
moz-do-not-send="true"><img
src="http://www.obase.com/images/signature/obaselogo.png"
moz-do-not-send="true"></a>
</p>
<p style="font-family:Calibri;font-size:10px;color:#9A9A9A;">Bu
elektronik posta ve onunla iletilen bütün dosyalar sadece
göndericisi tarafindan almasi amaclanan yetkili gercek ya da
tüzel kisinin kullanimi icindir. Eger söz konusu yetkili alici
degilseniz bu elektronik postanin icerigini aciklamaniz,
kopyalamaniz, yönlendirmeniz ve kullanmaniz kesinlikle yasaktir
ve bu elektronik postayi derhal silmeniz gerekmektedir. OBASE bu
mesajin icerdigi bilgilerin doğruluğu veya eksiksiz oldugu
konusunda herhangi bir garanti vermemektedir. Bu nedenle bu
bilgilerin ne sekilde olursa olsun iceriginden, iletilmesinden,
alinmasindan ve saklanmasindan sorumlu degildir. Bu mesajdaki
görüsler yalnizca gönderen kisiye aittir ve OBASE görüslerini
yansitmayabilir.<br>
<br>
Bu e-posta bilinen bütün bilgisayar virüslerine karsi
taranmistir.<br>
<br>
This e-mail and any files transmitted with it are confidential
and intended solely for the use of the individual or entity to
whom they are addressed. If you are not the intended recipient
you are hereby notified that any dissemination, forwarding,
copying or use of any of the information is strictly prohibited,
and the e-mail should immediately be deleted. OBASE makes no
warranty as to the accuracy or completeness of any information
contained in this message and hereby excludes any liability of
any kind for the information contained therein or for the
information transmission, recepxion, storage or use of such in
any way whatsoever. The opinions expressed in this message
belong to sender alone and may not necessarily reflect the
opinions of OBASE.<br>
<br>
This e-mail has been scanned for all known computer viruses.</p>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Scip mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Scip@zib.de">Scip@zib.de</a>
<a class="moz-txt-link-freetext" href="https://listserv.zib.de/mailman/listinfo/scip">https://listserv.zib.de/mailman/listinfo/scip</a>
</pre>
</blockquote>
<br>
</body>
</html>