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CP-Sat solver doesn't optimize objective function #971

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gregy4 opened this issue Dec 10, 2018 · 2 comments
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CP-Sat solver doesn't optimize objective function #971

gregy4 opened this issue Dec 10, 2018 · 2 comments
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Help Needed Modeling/Usage problem Lang: Python Python wrapper issue Solver: CP-SAT Solver Relates to the CP-SAT solver
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@gregy4
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gregy4 commented Dec 10, 2018

I try to minimize capacity of cumulative constraint for a scheduling problem with around 2 thousand jobs. First solution is found very quickly (in few seconds) but than I see nearly no future progress. When I changed upper limit of capacity variable to lower value, first solution is found again very quickly. For the example it was no problem to find a solution in interval 150 ... 200.

Since described behavior is not good for my needs when sum of capacities over cumulative constraints will be optimized I want to know it is a bug or not yet optimized case for CP-Sat solver so I can decide to implement / not implement my complete scheduling problem.

Thanks,
Jan

example.zip

@Mizux Mizux added Help Needed Modeling/Usage problem Solver: CP-SAT Solver Relates to the CP-SAT solver Lang: Python Python wrapper issue labels Dec 10, 2018
@lperron
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lperron commented Dec 10, 2018 via email

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lperron commented Jan 19, 2019

Anyway, scheduling with more than 2k intervals without decomposition is challenging.
I get some results with parallelism.

I will close the issue now.

@lperron lperron closed this as completed Jan 19, 2019
@Mizux Mizux added this to the v8.0 milestone Feb 12, 2021
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