[Cgl] Limit for GomoryCuts

[Ted Ralphs]

I merged to trunk and also stable/0.58.

Ted

On Fri, Dec 21, 2012 at 5:21 PM, Haroldo Santos <haroldo.santos at gmail.com>wrote:

> Should be fixed in trunk also, isn't ?
>
> On Fri, Dec 21, 2012 at 8:02 AM, John Forrest <john.forrest at fastercoin.com
> > wrote:
>
>>  Thomas,
>>
>> As I am unable to justify it and as removing made a slight improvement on
>> some very limited tests,  I have removed the 500 in Cgl/0.57 which is what
>> cbc uses.
>>
>> John
>>
>>
>> On 20/12/12 19:55, Thomas Schoenemann wrote:
>>
>> Hi all,
>>
>> my application of Cbc (where I added a GomoryCut generator) was producing
>> abnormally large cuts at the root node, although I had set a limit. So I
>> looked into the code and found this passage (line 679 of GomoryCut.cpp):
>>
>>
>>     limit = limitAtRoot_;
>>     if (!info.pass) {
>>       tolerance1=1.0;
>>       tolerance2=1.0e-2;
>>       tolerance3=1.0e-6;
>>       tolerance6=1.0e-7;
>>       tolerance9=1.0e-5;
>>       if (!limit||limit>=500)        <----!!!!!!!!!!!!!
>>     limit=numberColumns;
>>     } else {
>>
>>
>> It appears that Cbc does not set info.pass (whatever that signifies) and
>> in this case a limit of 500 or larger is simply ignored.
>>
>> I was wondering if there is a plausible reason for this. At the very
>> least I think this behavior should be documented in the text on
>> setLimitAtRoot(). Personally, I'd prefer if the part "||limit >= 500" was
>> removed, it does not make sense to me.
>>
>> I have a recent version of Cbc, checked out via svn (maybe there is
>> already a repository for 2.8?):
>>
>> URL: https://projects.coin-or.org/svn/Cbc/stable/2.7
>> Basis des Projektarchivs: https://projects.coin-or.org/svn/Cbc
>> UUID des Projektarchivs: 6f23a84d-0c12-0410-9f0c-b73a89ba9ce0
>> Revision: 1833
>> Knotentyp: Verzeichnis
>> Plan: normal
>> Letzter Autor: stefan
>> Letzte geänderte Rev: 1833
>> Letztes Änderungsdatum: 2012-12-04 11:21:49 +0100 (Di, 04. Dez 2012)
>>
>>
>> If you need my help, let me know.
>>
>> Best regards,
>>   Thomas Schoenemann
>>
>>
>>
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>>
>>
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>>
>
>
> --
> =============================================================
> Haroldo Gambini Santos
> Computing Department
> Universidade Federal de Ouro Preto - UFOP
> email: haroldo [at ] iceb.ufop.br
> home/research page: www.decom.ufop.br/haroldo
>
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>


-- 
Dr. Ted Ralphs
Associate Professor, Lehigh University
(610) 628-1280
ted 'at' lehigh 'dot' edu
coral.ie.lehigh.edu/~ted
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