[rules-users] Finding Multiple Solutions using Drools Planner

[Geoffrey De Smet]

I created this issue:
https://jira.jboss.org/browse/JBRULES-2703
AllBestSolutionsRecaller: Drools Planner should support returning all 
the solutions with the same best score found during solving, not just 
the first

With kind regards,
Geoffrey De Smet

Op 19-09-10 10:08, Geoffrey De Smet schreef:
> Hi Steve,
>
>   >  I need is to find all of the ideal solutions to my planning problem.
>
> This is impossible with a metaheuristic algorithm, such as tabu search
> and simulated annealing. So this is currently impossible with Drools
> Planner.
>
> I have a couple issues to implement exact algorithms on top of the rule
> engine based score calculation in Drools Planner:
> - brute force
> - branch and bound
> Even though branch and bound is a lot faster and more scalable than
> brute force, it's still enormously slower and less scalable than
> metaheuristics.
> For most real world datasets, exact algorithms are mostly useless due to
> the sheer size of the possible solution set. They have bigO notations
> such as n^n.
>
>
> What you can do of course, is extend the BestSolutionRecaller to recall
> the first 10 best solution (someone else has done this too, but didn't
> provide a patch, but feel free to make an issue).
> Combine that with a good max timemillisspend or unimproved step count.
>
> With kind regards,
> Geoffrey De Smet
>
> Op 18-09-10 22:03, Steve Ronderos schreef:
>>
>> Hello Drools Users,
>>
>> I've been investigating Drools Planner for a few weeks and can't figure
>> out how to accomplish a crucial requirement.
>>
>> In my application I need to have Planner return multiple solutions for
>> one planning problem. More specifically I need is to find all of the
>> ideal solutions to my planning problem. My problem is similar to the
>> n-queens problem in that there exist ideal solutions. It is however
>> somewhat simpler because the number of ideal solutions is fairly small
>> (maybe a max of 10 or so).
>>
>> I've looked through the mailing list archives for similar requests and
>> the best I could find was:
>>
>> http://drools-java-rules-engine.46999.n3.nabble.com/the-n-best-solutions-on-a-very-simple-test-case-td60618.html
>>
>> I took the advice of the poster in that thread and extended
>> BestSolutionRecaller. I'm running into some problems getting Planner to
>> continue after an optimal solution is found.
>>
>> My question is this. Is extending the BestSolutionRecaller the best way
>> to achieve my goal? Or do you think it would be simpler to do this
>> another way? Perhaps running Planner multiple times with already
>> discovered solutions provided as input.
>>
>> Any advice would be appreciated.
>>
>> Thanks,
>> Steve
>>
>>
>>
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>
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