[Coin-discuss] determining problem type in OSI

[Kish Shen]

Lou,

Thanks for your quick reply!

On Thursday 29 June 2006 18:14, Lou Hafer wrote:
> Kish,
>
> 	This could be implemented in OsiSolverInterface.  But a safe default
> implementation will boil down to the algorithm you suggest: scan columns
> looking for integer type.  It would fall to individual OSI maintainers to
> do something more efficient. A consequence of variable type being left to
> the underlying solver (setInteger is a pure virtual method).
>
> 	I take it using CbcModel::numberIntegers is not good, for some reason?
>
Yes and no, what I am developing is an interface to OSI (from our Constraint 
Logic Programming language ECLiPSe), and I would like the code to run with 
any solver that has an OSISolver interface. I have done specialisations for 
CBC/CLP, but would like to keep these to a minimum, and determining the 
problem type seems to be something OSI can do.

Actually, in addition to determining if a problem is MIP or linear, I would 
also like to determine if the problem is MIQP or QP (i.e. with a quadratic 
objective). I didn't ask this because OSI doesn't appear to support quadratic 
objectives, although from reading the documentation, CLP can solve quadratic 
problems.

> 	Still interested? A default could be installed in OsiSolverInterface
> without too much trouble. It would likely take a while for individual OSIs
> to incorporate something more efficient.
>
That would be very useful! Thanks in advance!

> 							Lou
>
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Cheers,

Kish