[Scip] Solving opb instances + initial solutions

[Luigi Malagò]

thank you so much!

best regards,
luigi

On Fri, Jan 20, 2012 at 5:59 PM, Stefan Heinz <heinz at zib.de> wrote:

> Hi Luigi,
>
> If you have solution candidate at hand, you can pass it to SCIP. This can
> be done via the interactive shell
>
> SCIP> read <solutionfile>.sol
>
> Therefore the solution has to be in a special form. That is
>
> x_1 value
> x_2 value
> x_3 value
> x_4 value
> ...
> x_n value
>
> If you just want to provide an upper bound you can set an objective limit.
>
> SCIP> set limit objective 100
>
> This can be done after you have load the problem into SCIP.
>
> If you are using SCIP via the callable library. Both versions are also
> possible. For that see:
>
> http://scip.zib.de/doc/html/**FAQ.html#Q3.2<http://scip.zib.de/doc/html/FAQ.html#Q3.2>
> http://scip.zib.de/doc/html/**scip_8h.html#**
> a4312fff0495bec0484a8fd9cd60ca**e8b<http://scip.zib.de/doc/html/scip_8h.html#a4312fff0495bec0484a8fd9cd60cae8b>
> http://scip.zib.de/doc/html/**scip_8h.html#**
> a3fd90b931b38d2d8f344114babc2a**67e<http://scip.zib.de/doc/html/scip_8h.html#a3fd90b931b38d2d8f344114babc2a67e>
>
> I would always prefer the first version (providing the solution) since
> improving heuristics could find a better solution.
>
> Best Stefan
>
>
>
>
> On 01/20/12 16:51, Luigi Malagò wrote:
>
>> hello mailing list,
>> right now i'm solving non linear pseudo-boolean functions f, which are
>> parsed from the OPB format, e.g.
>>
>> * #variable= 5 #constraint= 4
>> *
>> * this is a dummy instance
>> *
>> min: 1 x2 -1 x3 ;
>> 1 x1 +4 x2 -2 x5 >= 2;
>> -1 x1 +4 x2 -2 x5 >= +3;
>> 12345678901234567890 x4 +4 x3 >= 10;
>> * an equality constraint
>> 2 x2 +3 x4 +2 x1 +3 x5 = 5;
>>
>> (take from the http://www.cril.univ-artois.**fr/PB10/format.pdf<http://www.cril.univ-artois.fr/PB10/format.pdf>)
>>
>> i would like to speed up the solver, since i have (from some heuristic) a
>> candidate optima solution for each instance
>>
>> i am minimizing f and i would like like to provide an upper bound for it
>> (my candidate solutio from the heuristic).
>>
>> can i insert it the OPB file?
>> if not, in case I re-implement the opb_reader, which method should i call
>> to provide the solver with an initial solution?
>> i checked the documentation, but didnt find any usefull method. maybe i'm
>> looking in the wrong place..
>>
>> thanks alot for your help,
>> luigi
>>
>>
>> ______________________________**_________________
>> Scip mailing list
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>>
>
>
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