[Cbc] Improving performance for binary model

[John Forrest]

My guess is that Cbc is very bad at handling symmetry.  There is a lot 
of symmetry and trying some of the ways that Cbc can deal with symmetry 
I can get a solution of 296773 fairly quickly, but after an hour it does 
not seem to be closing the gap.  The other area where Cbc is failing 
somewhat is preprocessing - if I export the model several times (each 
time doing presolve) then I can make it smaller - this obviously wrong.

John Forrest

On 22/11/2019 15:44, Rui Patrocínio wrote:
> Hi,
> 
>   I'm trying to solve one instance of a problem that is taking a long 
> time to obtain a good solution. Since all variables are binary, probing 
> and implication cuts are doing some work and RINS and Vnd are apparently 
> also improving solutions. For other instances of the problem we are 
> solving, CBC has an acceptable performance but for this instance 
> apparently there's something going wrong (~20 seconds to get the optimum 
> solution with a commercial solver versus never getting the optimum 
> solution with CBC).
> 
>   If someone can take a look at the model and give me a hint of what is 
> going on, I would appreciate it.
> 
>   The model is at 
> https://drive.google.com/open?id=1bd4jWONmoyAKIi0oLa-AU-ZTu7_8qhb6
> 
> -- 
> SISCOG - Sistemas Cognitivos, SA
> 
> *Rui Patrocínio*
> 
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