[Cbc] Zero-half cuts announcement. Also an SOS question

[James Gunning]

Hi John, list
         Thanks very much for the effort. I've managed to build as you suggest.
That is indeed a sad story behind things, but I'm sure Alberto would have liked to
see his efforts appreciated and incorporated as you have so kindly done.

So far results seem a bit unusual using it:  generally a deal slower actually, 
with  more erratic
variations than with cbc "defaults". I don't understand things yet, clearly.

Thanks very much for your efforts either way.

PS: a very simple (ignoramus question), rather unrelated.
I have groups of binary variables where only 1 is allowed on, eg

x1+x2+x3 <=1
x4+x5+x6 <=1

Should I go to the trouble of using SOS in cbc, or is the constraint above 
enough, for performance reasons?

Best wishes all,
       James.



John Forrest wrote:
> James,
>
> After digging around a bit, I have put a first version of CglZeroHalf
> into Cgl trunk.
>
> Point Cbc to Cgl/trunk.  To do this copy Dependencies to xxxxxx and edit
> file to have
>
> Cgl               https://projects.coin-or.org/svn/Cgl/trunk/Cgl
>
> Then
> svn propset svn:externals -F xxxxxx . (note .). Then do svn up.
>
> You also have to add -DZERO_HALF_CUTS to configure (you may have to do
> make clean).
>
> This should work with Cbc stable 2.8 and trunk.
>
> By default these cuts are off.  To use add to your command line
> -zerohalfCuts root (or other options) or just -zero.  I think it may
> only help on a small subset of problems and may need some tuning.
>
> It is very sad that it took so long to get these cuts into Coin-OR. Here
> I would have thanked Alberto Caprara of Bologna University who provided
> the code, but unhappily he died in a mountaineering accident last year -
> see here for heartfelt tributes from colleagues.
>
> http://albertocaprara.people.ing.unibo.it/gbook.php?page=1
>
> John Forrest
> _______________________________________________
> Cbc mailing list
> Cbc at list.coin-or.org
> http://list.coin-or.org/mailman/listinfo/cbc

-------------- next part --------------
A non-text attachment was scrubbed...
Name: James_Gunning.vcf
Type: text/x-vcard
Size: 223 bytes
Desc: not available
URL: <http://list.coin-or.org/pipermail/cbc/attachments/20130111/041f5eb5/attachment.vcf>