[Cbc] Assisting the CBC preprocessor with problem setup

[Ted Ralphs]

Hi David,

The way most mathematical programming solvers work is that the modeling
language is completely independent of the solver (this is to allow all
modeling languages to work with all solvers instead of having proprietary
pairings). The modeling language converts the original model into a flat
file and it is in this process that one could exploit semantic/domain
knowledge. Once the instance is passed to Cbc, that information has been
stripped and Cbc can only use information contained in the flat file. I
guess the answer to your question would depend on how the instance file
gets created. It is in that process that additional knowledge could be
exploited, but that is outside of Cbc. There isn't a whole lot you can do
to help Cbc internally except by actually modifying the code to recognize
mathematical structures that arise in a particular domain or to customize
Cbc for a particular problem class by implementing specialized subroutines
that Cbc can use within its algorithm. This would require knowledge of the
algorithms Cbc uses, as well as some coding. Hope this answers your
question!

Ted

On Sun, Mar 8, 2020 at 7:18 PM David Coote <dccoote at outlook.com> wrote:

> Hi Ted,
>
> I guess it would help the CBC preprocesor if the optimisation model
> developers used semantic/domain knowledge to set fixed values as fixed as
> against relying on the preprocessor to detect fixed values in variables.
>
> Is there a list somewhere of what CBC users can do to assist the
> preprocessor?
>
> Thanks
>
> David
>
> _______________________________________________
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> Cbc at list.coin-or.org
> https://list.coin-or.org/mailman/listinfo/cbc
>


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