[SCIP] Question About IIS Functionality in SCIP

[Mark Turner]

Dear Ameya,


You should now be able to create an IIS with SCIP!

Things that you'd need to do:

- Clone the current master branch from the GitHub

- Build SCIP

- Load your infeasible problem in the SCIP shell with command `read 
path_to_instance_file` (you can simply write out the instance from your 
python script)

- Run the command `iis`

- Then either run `write iis path_to_new_instance_file` or `display iis` 
to see an IIS of your original instance.

It will take a couple of months before this feature is in the official 
SCIP release, and therefore also won't be available via PySCIPOpt until 
then. After that date there's going to be some nice Python function like 
`computeIIS` or `generateIIS`.


Cheers and have a good week,

Mark

On 1/12/25 12:20, Kamp, Dominik wrote:
> Dear Ameya,
>
> MIP-DD (https://github.com/scipopt/MIP-DD) on the develop branch provides some kind of IIS-heuristic, which can simply be set up by linking SCIP to it and adding option -o feasible when calling.
>
> However, since it is rather designed to investigate the underlying solver instead of the given problem, you might want to wait for the IIS-plugin in SCIP announced in an earlier message on this list, which could be available soon on the master branch of SCIP.
>
> Best regards,
>
> Dominik
>
>> On 12. Jan 2025, at 07:50, Ameya Munagekar <amunagekar at gmail.com> wrote:
>>
>> Hi SCIP Team,
>>
>> I hope you're doing well!
>>
>> I'm reaching out to check if SCIP has a feature for identifying an Irreducible Inconsistent Subsystem (IIS),
>> I'm working on a project in python where I need to analyze infeasibility in optimization models, and I was wondering if SCIP can help with this directly or if there's a recommended workaround, any pointers or advice would be really helpful.
>>
>> Thanks in advance for your time!
>> Regards,
>> Ameya
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