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I have produced some new trunk versions. I found I had been
updating the wrong versions so Cbc/trunk will be updated again in a
day or two.<br>
<br>
Cgl has some fixes plus two cut generators donated by Giacomo
Nannicini. One is an alternative reduce and split generator (G.
Cornuejols and G. Nannicini. Practical strategies for generating
rank-1 split cuts in mixed-integer linear programming. <i>Mathematical
Programming Computation</i>, 3(4):281-318, 2011) while the other
is a robust Gomory generator (G. Cornuejols, F. Margot and G.
Nannicini. On the safety of Gomory cut generators. <i>Mathematical
Programming Computation</i>) - see
<pre wrap=""><a class="moz-txt-link-freetext" href="http://faculty.sutd.edu.sg/%7Enannicini/index.php?page=publications">http://faculty.sutd.edu.sg/~nannicini/index.php?page=publications</a>
<font face="sans-serif">As reduce and split cuts can be slow, the full benefit will not be felt before my next Cbc/trunk when there will be a parameter for specifying number of rounds to do for expensive cuts.
Coinutils/trunk has a few changes to presolve for special variables and badly scaled problems.
Cbc will change again, but one feature of interest to Allan </font><font face="sans-serif">Wechsler is -extraVariables 20 (or some such) which switches on a trivial re-formulation to group variables with same cost together.
The feature which may affect people is for returning a primal infeasibility ray. The previous code passed the unit test, but on close examination that was when Clp had switched to Primal. Hopefully I have now got the signs right for Dual as well. So if you use infeasibility rays - try trunk and if fails reverse signs! At least it should be more consistent - and should be same as other Lp codes.
John Forrest
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