[Osi] milp support in OSI

[Ted Ralphs]

We've had fairly lengthy and detailed discussion about all of this in
the past and I believe there was even a formal talk given with a
preliminary design for a new OSI based on the OS spec. Before we
re-invent the wheel, someone should dig all of that out, including the
previous e-mail threads where I think the very same discussions has
already been had. Might save us some time and energy :).

Cheers,

Ted

On Fri, Apr 24, 2009 at 3:47 AM, Kipp Martin <kmartin at chicagobooth.edu> wrote:
> Hi Matt:
>>
>> I've often thought that the OS spec would be a good starting point for
>> this discussion.   I need to look into it some more, though.
>
>
>
> There are four aspects to the OS spec:
>
> 1. OSInstance (along with readers and writers) -- the API to build
> and/or access a very general model instance.  It has get, set, and
> calculate (including forward and backward AD calls) methods.
>
> 2. OSOption (along with readers and writers) -- the API for solver options
>
> 3. OSResult (along with readers and writers) -- the API for solver results
>
> 4. OSModification -- the API for addition / modification / deletion.
>
> The first three are done. The last is obviously the most difficult and
> we did not want to start without help/input/guidence/marching orders
> from others (like the Osi mailing list).
>
> Cheers
>
>>
>>> Cheers
>>>>> --Laci
>>>>>
>>>>> On Thu, 23 Apr 2009, Matthew Galati wrote:
>>>>>
>>>>>> Currently OSI does support the branchAndBound function to solve a MILP.
>>>>>> However, I don't see any access methods for MILP statistics afterwards (or
>>>>>> any other MILP-type manipulation methods). Is there any intention to add
>>>>>> this? For example, how do I get the number of nodes used, the gap, how do I
>>>>>> set options specific to MILP for say, Cplex or Xpress calls?
>>>>>>
>>>>>> I can always cast an Osi to an OsiCpx and then get CpxLp and CpxEnv ptrs and
>>>>>> then use Cpx directly -- but obviously all of this defeats the purpose of
>>>>>> having OSI.
>>>>>>
>>>>>> Thanks,
>>>>>> Matt
>>>>>>
>>>>> _______________________________________________
>>>>> Osi mailing list
>>>>> Osi at list.coin-or.org
>>>>> http://list.coin-or.org/mailman/listinfo/osi
>>>
>
>
> --
> Kipp Martin
> Visiting Professor
> University of Cincinnati
> College of Business
> Dept. of QAOM
> 525 Lindner Hall
> Cincinnati, OH  45221-0130
>
> 513-556-0404
>
> kipp.martin at chicagogsb.edu
> http://homepages.uc.edu/~martinrk/
> https://projects.coin-or.org/OS
> http://www.coin-or.org
>
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>



-- 
Dr. Ted Ralphs
Associate Professor, Lehigh University (permanent)
Visiting Professor, Monash University (current)
(610) 628-1280
ted 'at' lehigh 'dot' edu
coral.ie.lehigh.edu/~ted