[rules-users] Assignment problem

[Geoffrey De Smet]

Op 01-12-11 01:53, Patrik Dufresne schreef:
> Hi,
>
> I am a Java developer and I am currently working on a work force 
> management software for food compagnies. So far, I've decided to use 
> constraint programming (CP) to find a solution to the problem. The 
> current version is using JaCoP as a solver, but I find it hard to make 
> it support soft-constraint and it only use Depth First search. So I'm 
> looking around for a different solver engine and Drools Planner seams 
> to fit my need. I'm just concern about it's speed since I don't see 
> any way to add global constraint (like all-different, Count, Among, etc.)
Those global constraints break down into simple score rules, in an 
Object Orientated manner (instead of twiddling with primitive arrays). 
For example:

all different:
   Assignment($x : x)
   not Assignment(x == $x)

Through ReteOO and rule engine forward chaining, these are made fast and 
scalable with indexing, incremental score calculation (=delta's), ...
>
> I've look closely to the nurse rostering example. My problem is very 
> similar. Let say, I have 150 nurses, ~42 different skills, 9 shifts, 
> ~300 events to be assigned. Whats make it easier compare to the 
> example, I only need to plan one week. My question is simple, does 
> Drools will be able to handle it ?
Yes. Planner is used successfully in far greater problems sets than this :)
Assigning 300 events is really not much: most of the examples already 
have 1000-5000 planning entities to schedule (to multiple variables 
sometimes, while nurse rostering only has 1 variable, the nurse).
>
> To give a better understanding of the problem I'm trying to solve, 
> I've attach a PDF document with more explanations. 
> (https://docs.google.com/open?id=0BykkHu_UReIvYzg3NmM2YmUtYjVhNy00NjgwLTliNjctNWJjZTMyNjU0MDM2)
>
> Thanks to post your opinion.
> Any tips are welcome.
Once you've got the Planner implementation working well, benchmark it 
against your JaCoP results and blog/tweet them :)
>
> -- 
> Patrik Dufresne
>
>
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-- 
With kind regards,
Geoffrey De Smet

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