[SCIP] Defining binary variables for "top level" branching

[Yuji Shinano]

Dear Vladimir V. Voloshinov,

We are working on UG documentation currently. Hopefully, it comes at the next major release of SCIP Optimization Suite.
You can customize your own racing ramp-up. You need to prepare a set of parameter files for the customized racing.
A brief introduction is presented in the previous SCIP workshop Q&A session of FiberSCIP below.
https://scipopt.org/workshop2020/
You can get the slide from the page. (The customized racing setting is on p.28)

If you need more help, please directly contact to me.

Best regards,
Yuji


On 2020/07/07 0:28, Vladimir V. Voloshinov wrote:
> Dear SCIP developers,
>
> We have a set of MIP problems with all-binary variables and ZERO objective function (so, we are looking for a feasible solution).
> Typical dimensions are: about 6000 binary variables and 3000 constraints.
> FiberSCIP with 20 threads and (almost) default settings solves these problems in about 10 minutes but we have an idea to reduce solving time by a "special ramp-uping".
> The thing is that we know, in advance, about 30 variables, which are worth (we think so) to be selected for creation of "search subtrees' root nodes" by fixing their values to 0 or 1.
>
> I searched for proper settings in UG-parameters (*.prm file generated by fscip or parascip), but could not find.
> So we have a couple of questions.
> 1. Is it worth trying "home-bred" rump-up rules, or should we trust UG heuristics?
> 2. Is it possible to set the "rule for ramp-up phase" mentioned above somehow? If yes, in what way: by some settings of UG-parameters or we need UG API?
>
> And almost the same question regarding SCIP: is it possible to set the rule for "search tree 2nd level nodes creation", or we need SCIP API. e.g. from https://www.scipopt.org/doc/html/group__BRANCHINGRULES.php?
>
> Sincerely yours,
> Vladimir V. Voloshinov,
>


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Yuji Shinano
Zuse Institute Berlin
Takustrasse 7, 14195 Berlin-Dahlem, Germany
Phone:+49 30 84185-477, Fax:+49 30 84185-269