[Cgl] length of gomory cuts

[John J Forrest]

Ashutosh,

It is a feature rather than a full blown bug.

The Gomory cut is generated from the tableau and it is the length of that
cut which is tested.  So the first cut generated for acc3 has 499 elements
and that is less than 600.  However the cut has to be converted back to
just have column elements rather than slacks.  Normally this does not make
very much difference.  However with this problem - 3249 rows, 1620 columns
and continuous and integer objectives of 0.0, the converted cut has 1554
elements.

I can modify the code to have another limit - which would not impact
current users or I could make the limit on final number, which would change
actions for current users.  What would people prefer?

John Forrest


                                                                                                                
  From:       Ashutosh Mahajan <asm4 at lehigh.edu>                                                                
                                                                                                                
  To:         cgl at list.coin-or.org                                                                              
                                                                                                                
  Date:       09/18/2008 01:19 AM                                                                               
                                                                                                                
  Subject:    [Cgl] length of gomory cuts                                                                       
                                                                                                                





hi all,
i am having problems in setting the maximum length of gomory cuts generated
by
CglGomory. i do:

CglGomory *gomory = new CglGomory;
gomory->setLimit(600);
gomory->generateCuts(*si, cutlist);

full code is available at http://coral.ie.lehigh.edu/~asm4/src/tmp/

however, the cuts generated have length more than 1500 for
instances acc3, acc4, acc5 (http://www.ps.uni-sb.de/~walser/acc/acc.html).
i
see this problem in both /trunk and /stable/0.53/.

is the above the right way to set limit? or is there a bug?
--
regards
Ashutosh Mahajan
http://coral.ie.lehigh.edu/~asm4

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