[Scip] Quick question on how to get infesibility info from presolver or after solve returns infeasible

[michael.winkler@zib.de]

Hi Guillermo,

for now there is no easy way determine a reason for infeasibility in SCIP.

Like Stefan suggested you can try the beta version changing a problem to a
"MinUC" problem, determine the minimal number of unsatisfied constraints.
This can also be done via SCIPtransformMinUC().

Getting a (minimal) set of variables which led to infeasibility is not
(yet) possible (in any direct approach).

Best, Michael

> Thank you very much for your suggestion, Stefan. I am interested in using
> SCIP integrated within a C++ application. As a consequence the objective
> is to be able to get infeasibility information via some API just as the
> other APIs used for problem setup and execution control. It would be nice
> to get that sort of information for both the presolve phase -- if that
> phase already identifies infeasibilities, -- and also for the actual
> solution if there are any other infeasibilities at a node not already
> picked up by the presolver.
>
> Are there any simple APIs for these purposes? Is it done via call backs?
> If any of these, are there any examples available?
>
> I thank you very much for your help
>
> Best regards
>
> Guillermo
>
> -----Original Message-----
> From: Stefan Heinz [mailto:heinz at zib.de]
> Sent: Tuesday, October 02, 2012 9:19 AM
> To: Guillermo Irisarri; Scip at zib.de
> Subject: Re: Quick question on how to get infesibility info from presolver
> or after solve returns infeasible
>
> Hi,
>
> you can set the verbosity level to 5. This will give you some more
> information.
>
> SCIP> set display verblevel 5
>
> Besides that you can try the beta version of the infeasibility analysis
> tool:
>
> SCIP> read <file>
> SCIP> change minuc
> SCIP> optimize
>
> Best Stefan
>
>
> On 10/02/2012 03:10 PM, Guillermo Irisarri wrote:
>> Dear Mr Heinz:
>>
>> I have looked at the documentation and cannot find a way to get the
>> information above out of SCIP. Could you point me in the right direction
>> or, perhaps, give an idea on how to proceed. If there are any examples,
>> a pointer to those would be very useful.
>
>>
>> Thanks
>>
>> Guillermo Irisarri
>>
>>
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>
>
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