[Cbc] Osi Interface for Cbc (and deprecation thereof)?

[Matthew Gidden]

Hi Ted, Stefan, others,

First of all, thank you very much for taking the time to reply! I'll move
ahead for now using the current OsiCbcSolverInterface. As I need additional
MILP-specific support/require better performance, I'll revisit the
potential upgrade. I'll hit the list again at that point to talk about an
upgrade strategy.

Thanks again!


On Wed, Feb 19, 2014 at 9:31 AM, Ted Ralphs <ted at lehigh.edu> wrote:

> To echo what Stefan said, there is not really general agreement about the
> usefulness/appropriateness of OsiCbc  and/or the usefulness of Osi for
> controlling MILP solvers in general. I personally find Osi is perfectly
> suitable and useful for calling MIP solvers and allows the ability to
> easily switch out different solvers, which is exactly what Osi is supposed
> to do.  Yes, it is true that the design of Osi is geared towards LP solvers
> and the user has to understand that some of the functionality will not work
> when solving a MILP. Nevertheless, Osi is perfectly serviceable as an
> interface to MILP solvers until there is a better alternative (which will
> hopefully happen at some point).
>
> With that said, OsiCbc is only "deprecated" inasmuch as it is not
> well-maintained. However, I am personally using it for cases when I really
> do need to access solvers through Osi. It works (subject to the
> aforementioned performance penalties). I would be very happy to see it
> worked on and its performance improved. I would also be happy to help
> maintain it going forward.
>
> Cheers,
>
> Ted
>
>
> On Tue, Feb 18, 2014 at 11:16 PM, Stefan Vigerske <
> stefan at math.hu-berlin.de> wrote:
>
>> Hi,
>>
>>
>> On 02/18/2014 05:56 PM, Matthew Gidden wrote:
>>
>>> Hi all,
>>>
>>> I was curious about the status of an OsiSolverInterface for Cbc models. I
>>> note that the current OsiCbcSolverInterface is deprecated, and it's
>>> suggested that I use the CbcSolver interface, hence my conundrum: I'd
>>> like
>>> to use the virtual Osi interface, but I'm wary of using something that's
>>> deprecated. I was hoping the list could help me understand:
>>> a) why the Osi Cbc interface was deprecated in the first place
>>>
>>
>> Noone has been developing or updating it anymore. And the performance you
>> get with it is inferior to what you get with the usual CbcSolver interface.
>> Also MIP support in Osi is very limited, so interest for reviving OsiCbc
>> by the Cbc developer has been very low, I believe.
>>
>>
>>  b) a suggested path forward (I assume writing my own custom interface for
>>> the CbcSolver)
>>>
>>
>> driver3.cpp and driver4.cpp in Cbc/examples may be a starting point.
>>
>>
>>  If the answer is writing a new Osi-to-(new)CbcSolver interface, I'd be
>>> happy to contribute that back into coin.
>>>
>>
>> I know some people who would like this to see.
>>
>> Stefan
>>
>>
>>> Warm regards,
>>>
>>>
>>>
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>>>
>>>
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>
>
>
> --
> Dr. Ted Ralphs
> Associate Professor, Lehigh University
> (610) 628-1280
> ted 'at' lehigh 'dot' edu
> coral.ie.lehigh.edu/~ted
>



-- 
Matthew Gidden
Ph.D. Candidate, Nuclear Engineering
The University of Wisconsin -- Madison
Ph. 225.892.3192
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