[Cgl] Limit for GomoryCuts

[Haroldo Santos]

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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-- 
=============================================================
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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