[Scip] SCIP-2.1.1 and SCIP-3.0.1 give different optimal values

[Timo Berthold]

Hi Masahiro,

me and most of the SCIP team are currently on a business trip, and will
have a look into it after our return next week.
If you have the possibility to compile SCIP on your own, you might follow
the instruction at http://scip.zib.de/doc/html/DEBUG.shtml
Write out the solution with SCIP 2.1.1, compile SCIP 3.0.1 with a
#define SCIP_DEBUG_SOLUTION "<pathtothesolfile>.sol" in debug.h
and run SCIP 3.0.1.

@Victor: Thanks for your very quick reply, that's a good hint. :-)

Best regards,
Timo

> This looks like it might be a bug in presolve.  As a guess I set maxrounds
> to 3 in 3.0.1 and then it found the right optimal solution.
>
> Victor
>
>
> On Fri, May 31, 2013 at 10:39 AM, Masahiro Sakai
> <masahiro.sakai at gmail.com>wrote:
> Hi,
>
> I solved a minimization MILP problem attached as rand717_l2.wcnf.lp.gz
> using SCIP-2.1.1 and SCIP-3.0.1, but they delivered differenct results:
>
> * SCIP-2.1.1 returned 2205487 as the optimal value, while
> * SCIP-3.0.1 returned 2223207 as the optimal value.
>
> I'm wondering whether it is a bug of SCIP-3.0.1 or just a numerical
> problem.
>
> The problem rand717_l2.wcnf.lp is converted from a weighted partial
> Max-SAT problem rand717_l2.wcnf.gz. And I used SCIP binaries
> downloaded from the SCIP website: scip-2.1.1.linux.x86_64.gnu.opt.spx.zip
> and scip-3.0.1.linux.x86_64.gnu.opt.spx.zip.
>
> Thanks in advance,
>
> Masahiro
>
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>
>
> On Fri, May 31, 2013 at 10:39 AM, Masahiro Sakai
> <masahiro.sakai at gmail.com>wrote:
>
>> Hi,
>>
>> I solved a minimization MILP problem attached as rand717_l2.wcnf.lp.gz
>> using SCIP-2.1.1 and SCIP-3.0.1, but they delivered differenct results:
>>
>> * SCIP-2.1.1 returned 2205487 as the optimal value, while
>> * SCIP-3.0.1 returned 2223207 as the optimal value.
>>
>> I'm wondering whether it is a bug of SCIP-3.0.1 or just a numerical
>> problem.
>>
>> The problem rand717_l2.wcnf.lp is converted from a weighted partial
>> Max-SAT problem rand717_l2.wcnf.gz. And I used SCIP binaries
>> downloaded from the SCIP website:
>> scip-2.1.1.linux.x86_64.gnu.opt.spx.zip
>> and scip-3.0.1.linux.x86_64.gnu.opt.spx.zip.
>>
>> Thanks in advance,
>>
>> Masahiro
>>
>> _______________________________________________
>> Scip mailing list
>> Scip at zib.de
>> http://listserv.zib.de/mailman/listinfo/scip
>>
>>
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