[Scip] SCIP solution parameters adjustment

[Gerald Gamrath]

Hi Yifan,

do you use the interactive shell of SCIP? If you type "set" in there, 
you get the menu for parameter settings. In this first menu, you have to 
choose the kind of parameter you want to change, e.g., parameters about 
heuristics, cutting planes, numerics, limits, or global emphasis 
settings. After that, you get to a sub-menu where you can change single 
parameters of choose the actual plugin (like a specific heuristic), you 
want to change some parameter for.

Probably most interesting for you are the following settings:
1) parameters in the "limits" submenu, e.g. absgap and gap
2) the global emphasis settings in the "emphasis" submenu

You can also play with emphasis settings for heuristics, separation and 
presolving by, e.g., "set heuristics emph xyz", where xyz should be off, 
fast, or aggressive. Those are "meta"-settings, you will see the actual 
parameters changed when changing one of the emphasis settings. You can 
write out all (changed) parameters by "set (diff)save xyz.set".

Have a great holiday!

Best,
Gerald

Am 20.12.2012 18:30, schrieb yfli @iastate.edu:
> Good afternoon everyone,
> I am a PhD student in power system planning, recently I am using SCIP 
> to solve our monster MILP problem, which has million variable and 
> constraints. So far SCIP performed very well on a high performance 
> computer. However, I wonder what solution parameters can I adjust to 
> lower solution quality or increase tolerance. In CPLEX, I remember 
> there are mipgap, solution strategy, relative gap, .etc to adjust, but 
> when I try to find these parameters, I got lost in the 5000-line .set 
> file... So anyone knows what solution parameter and tolerance can I 
> change to put emphasis on solution speed? I appreciate it very much. 
> Many thanks and have a great holiday!
> Best,
> Yifan
>
> -- 
> /Yifan Li
> Electrical and Computer Engineering
> Coover 2215, ECpE
> Iowa State University/
>
>
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