[SCIP] SCIP and Pyomo

[Salvador Pineda]

Dear Vladimir,
Thanks a lot for your reply.
Yes, I'm just interested in a local optimal solution to a continuous
non-convex problem. Then I was wondering if moving to SCIP would entail any
advantage. Based on your response, I would say there is no advantage.
I am not sure either I completely understand the advantage of generating
myself the NL-files. In fact, I use Pyomo because to avoid that. But
probably there is something I am not taken into account. Would you
elaborate on the advantages of generating NL-files myself?
Best,
Salva.

On Mon, May 25, 2020 at 4:19 PM Vladimir V. Voloshinov <
vladimir.voloshinov at gmail.com> wrote:

>
> Dear Salva,
>
> if there are no any discrete variables in your problem and you do not want
> to treat it as a global optimization one, e.g. it is convex, or unimodal
> (there is only one optimal solution), and local optimum will be enough for
> you, then, you can use IPOPT "directly" from Pyomo. There is special
> Pyomo-IPOPT interface...
> But, frankly speaking, it is much more convenient to use IPOPT by the same
> scheme: Pyomo->NL-file->IPOPT->SOL-file->Pyomo. E.g. you can generate
> NL-files on your "small computer" and send them to a power server with
> IPOPT (may be run in multi-threaded  mode on multi-core system) for solving
> and return SOL-files  back for processing results via Python.
>
> Vladimir.
>
> On Mon, May 25, 2020 at 4:40 PM Salvador Pineda <spinedamorente at gmail.com>
> wrote:
>
>> Thanks a lot Vladimir,
>> But then, what is the advantage of using IPOPT under SCIP with PYOMO
>> versus using directly IPOPT in PYOMO?
>> Salva.
>>
>> On Mon, May 25, 2020 at 2:35 PM Vladimir V. Voloshinov <
>> vladimir.voloshinov at gmail.com> wrote:
>>
>>> Dear Salvador,
>>> answering your questions (basing on our experience of SCIP usage) :
>>> 1) Yes, SCIP does use IPOPT for NLP, but, theoretically other
>>> NLP-solvers may be used via NLP API
>>> <https://scip.zib.de/doc-7.0.0/html/group__NLPIS.php>
>>> 2) Our team successfully use SCIPAMPL (AMPL-compatible SCIP-version) by
>>> Pyomo: Pyomo makes AMPL NL-file as SCIPAMPL-input; SCIPAMPL returns AMPL
>>> SOL-file as output; Pyomo reads SOL-file.
>>> It is important that above scheme may be used for ParaSCIP & FiberSCIP
>>> with some additional trick...
>>>
>>> Yours sincerely,
>>> Vladimir V. Voloshinov, web: GoogleScholar profile
>>> <https://scholar.google.ru/citations?hl=en&user=-m4QhNEAAAAJ&view_op=list_works&sortby=pubdate>
>>>
>>> On Mon, May 25, 2020 at 2:06 PM Salvador Pineda <salvapineda2 at gmail.com>
>>> wrote:
>>>
>>>> Hi,
>>>> I have a couple of questions regarding SCIP solver.
>>>> 1) Does SCIP rely on other solvers such as IPOPT to solve non-linear
>>>> optimization problems?
>>>> 2) Can SCIP be used under PYOMO?
>>>> Thanks a lot!
>>>> Salva.
>>>> _______________________________________________
>>>> Scip mailing list
>>>> Scip at zib.de
>>>> https://listserv.zib.de/mailman/listinfo/scip
>>>>
>>>
>>>
>>
>> --------------------------------------------------------------------------
>>
>>
>
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