[Cbc] Nauty / Symmetry detection support

[John Forrest]

Nauty is to some extent a "WIP".  I would be glad if someone were to 
improve it.

I have fixed compile problem in trunk. I have also added an -orbit 
simple option, which just adds symmetry breaking constraints.

If you wish to send me a problem, I can look to see what nauty or other 
options can do to improve situation.

John Forrest



On 27/10/2018 23:01, Tiago Maduro Dias wrote:
> Hi,
>
> I’m dealing with a problem that has quite a few symmetries but I’m 
> finding that adding restrictions to reduce or eliminate them has a 
> significant impact on CBC’s execution time.
>
> I was wondering if there were alternative and possibly more efficient 
> approaches, such as using Nauty.
>
> After some time fiddling, I’m coming to the conclusion that Nauty 
> support in CBC is currently broken, e.g., there’s a reference to 
> rootModels[i]->zapSymmetry() in Cbc/src/CbcModel.cpp but I see no 
> declaration for it anywhere in the code.
>
> This made me wonder if Nauty is supposed to work with the trunk 
> version of CBC or if it's just an abandoned WIP? If the former, can 
> someone give me some pointers about what I should be doing to get it 
> to compile?
>
> Best regards,
>
> Tiago Maduro Dias.
>
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