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<p>Allan,<br>
<br>
I would suggest looking at the example driver4.cpp. With that you should get all the performance advantages of the stand-alone solver.<br>
<br>
John Forrest<br>
<br>
<img width="16" height="16" src="cid:1__=0ABBFFB1DFA789938f9e8a93df938@us.ibm.com" border="0" alt="Inactive hide details for acw---12/16/2008 07:15:55 PM---A little while ago I sent the following message to Coin-discuss. The l"><font color="#424282">acw---12/16/2008 07:15:55 PM---A little while ago I sent the following message to Coin-discuss. The last time I paid serious attention, there was no mailing</font><br>
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<font size="2" color="#5F5F5F">From:</font></td><td width="100%"><img width="1" height="1" src="cid:2__=0ABBFFB1DFA789938f9e8a93df938@us.ibm.com" border="0" alt=""><br>
<font size="2">acw@ascent.com</font></td></tr>
<tr valign="top"><td width="1%"><img width="96" height="1" src="cid:2__=0ABBFFB1DFA789938f9e8a93df938@us.ibm.com" border="0" alt=""><br>
<font size="2" color="#5F5F5F">To:</font></td><td width="100%"><img width="1" height="1" src="cid:2__=0ABBFFB1DFA789938f9e8a93df938@us.ibm.com" border="0" alt=""><br>
<font size="2">cbc@list.coin-or.org</font></td></tr>
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<font size="2" color="#5F5F5F">Date:</font></td><td width="100%"><img width="1" height="1" src="cid:2__=0ABBFFB1DFA789938f9e8a93df938@us.ibm.com" border="0" alt=""><br>
<font size="2">12/16/2008 07:15 PM</font></td></tr>
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<font size="2" color="#5F5F5F">Subject:</font></td><td width="100%"><img width="1" height="1" src="cid:2__=0ABBFFB1DFA789938f9e8a93df938@us.ibm.com" border="0" alt=""><br>
<font size="2">[Cbc] Clues sought on how to diagnose Cbc performance changes</font></td></tr>
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A little while ago I sent the following message to Coin-discuss. The last time I paid serious attention, there was no mailing list devoted to Cbc, but now I discover that there is, and this was probably a better place to ask my question. I apologize to those who are seeing my query twice.<font size="4"> </font><font size="2" color="#800080"><br>
----- Forwarded by Allan C Wechsler/Cambridge/Ascent on 12/16/2008 07:11 PM -----</font><font size="4"> </font>
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<tr valign="top"><td width="11%"><font size="2" color="#5F5F5F">From:</font><font size="4"> </font></td><td width="89%"><font size="2">acw@ascent.com</font><font size="4"> </font></td></tr>
<tr valign="top"><td width="11%"><font size="2" color="#5F5F5F">To:</font><font size="4"> </font></td><td width="89%"><font size="2">coin-discuss@list.coin-or.org</font><font size="4"> </font></td></tr>
<tr valign="top"><td width="11%"><font size="2" color="#5F5F5F">Date:</font><font size="4"> </font></td><td width="89%"><font size="2">12/16/2008 06:14 PM</font><font size="4"> </font></td></tr>
<tr valign="top"><td width="11%"><font size="2" color="#5F5F5F">Subject:</font><font size="4"> </font></td><td width="89%"><font size="2">[Coin-discuss] Clues sought on how to diagnose Cbc performance changes</font></td></tr>
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About two years ago, we built an application around the then-current release of Cbc. For the sake of discussion, call this "Version A."<font size="4"> </font><br>
<br>
Very recently, we downloaded a much more recent release, and re-architected the application. This "Version B" has exactly the same API as Version A, but the details of the systems integration are different in a variety of ways. <br>
<br>
Version A was essentially a hack-job on CbcMain's command-line interface: for example, it launched the Cbc solver by faking a "branch" command. Version B, in contrast, was written along the lines of some of the simpler examples in Cbc/examples, and since it leaves out most of the machinery of the command-line interface, it's about a factor of ten shorter.<font size="4"> </font><br>
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To my (perhaps naive) surprise, Version B is far less efficient than Version A. On one small example problem, Version A processed 24 nodes to solve the problem, while Version B processed 52 nodes, more than twice as many.<font size="4"> </font><br>
<br>
It is obvious that we have made at least one ill-advised change in cut, node, or branch selection, or in presolve/postsolve processing. We have avoided customizations we did not understand, and in most cases used the default choices that were implicit in the two versions of Cbc.<font size="4"> </font><br>
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We have tried more-or-less blind flailing in our attempts to regain the lost performance efficiency, exploring Version A and experimenting with transplanting various customizations from there to Version B, but nothing has had an effect of more than about 10%, compared to the more than 2-to-1 discrepancy between the two versions.<font size="4"> </font><br>
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Obviously Cbc has not regressed; it is our own ignorance of how to configure it that is at fault. But we don't even know how to begin the analysis that would reveal fruitful avenues to take. We would appreciate any advice. I haven't provided much detail about our configuration, because I don't know what aspects of it are important, but I'd be pleased to answer any questions that would help someone give us some guidance.<font size="4"> </font><br>
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Thank you for your consideration, and for the enormous amount of work that has clearly been put into making Cbc a useful tool.<tt>_______________________________________________<br>
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