[rules-users] Multiplying the count of each score rule [planner]

[Geoffrey De Smet]

Op 19-12-11 15:22, Geoffrey De Smet schreef:
>
>
> Op 19-12-11 15:04, Patrik Dufresne schreef:
>> Hi Geoffrey,
>>
>> Thanks for your opinion. I will try to implement what I call a 
>> HardAndSoftPriorityScoreDefinition and give it back to the community. 
>> Where is the best place to post a 'patch' ?
> Create a pull request :) on http://github.com/drools-planner
Sorry, on https://github.com/droolsjbpm/drools-planner
> https://github.com/droolsjbpm/droolsjbpm-build-bootstrap/blob/master/README.md
>
> Design wise, I recommend:
> It's basically about allowing a dynamic number of levels, instead of 
> just 2 (hard and soft).
> it should not extend AbstractHardAndSoftScore, just extend AbstractScore
> Because it cannot correctly implement HardAndSoftScore.getSoftScore();
> I should just have a Map<Integer, Integer> levelToScoreMap; (no int 
> hardScore or int softScore)
> hardScore is like level 0.
> softScore is like level -1.
> This allows for:
> softerScore at level -2
> harderScore at level 1
> Higher level is more important then lower level.
> The class name should probably contain the word "Level".
>>
>> 2011/12/19 Geoffrey De Smet <ge0ffrey.spam at gmail.com 
>> <mailto:ge0ffrey.spam at gmail.com>>
>>
>>
>>
>>     Op 14-12-11 18:40, Patrik Dufresne schreef:
>>>     Hi,
>>>
>>>     I'm still in process to model my planning problem and I have
>>>     some difficulties in defining the correct weight of soft
>>>     constraints. I have soft constraints with different priorities :
>>>     C1, C2, C3, ..., Cn where C1 are higher then C2. Currently, I've
>>>     tried to set different weight for each of them : C1 get higher
>>>     weight. But it's not sufficient since multiple C2 may balance
>>>     one C1. What I really need is to set the priority to every soft
>>>     constraints.
>>>
>>>     Solution #1 :
>>>     My first thought it to implement a new score definition
>>>     (HardAndSoftPriorityScoreDefinition) having separate soft score
>>>     for each priority. The rule may insert ConstraintOccurence by
>>>     defining the weight and the priority. This solution seems
>>>     elegant but require effort to implement the score definition,
>>>     the score calculation, and other things I don't even know about.
>>     That is the perfect solution to your problem. Start by copy
>>     pasting DefaultHardAndSoftScoreDefinition and work your way from
>>     there.
>>     You'll need to create at least a ScoreDefinition, ScoreCalculator
>>     and Score.
>>
>>     I've been thinking about adding such a "dynamic" score definition
>>     to planner's build-in scores,
>>     but so far every use case where the developers said they needed
>>     this, it turned out end-users meant it differently:
>>     when you break a 100 C2's, then it's better to break 1 C1 instead...
>>>
>>>     Solution #2 :
>>>     The other solution is stated in the Drools Planner User Guide :
>>>
>>>         "Most use cases will also weigh their constraints
>>>         differently, by multiplying the count of each score rule
>>>         with its weight. For example in freight routing, you can
>>>         make 5 broken "avoid crossroads" soft constraints count as
>>>         much as 1 broken "avoid highways at rush hour" soft
>>>         constraint. This allows your business analysts to easily
>>>         tweak the score function as they see fit."
>>>
>>>     Even tough I don't know how to implement this, it's seems much
>>>     easier to achieve since it's only a rule. Compare to solution
>>>     #1, it's lack the support of soft constraints with same priority
>>>     but different weights.
>>     That text describes plain-old weighting. Say C1 weights 100 and
>>     C2 weights 2, then you can break 50 C2's for every 1 broken C1.
>>
>>     This is far easier and most of the time end-users actually mean this.
>>     Make exaggerated examples (1000 C2's broken vs 1 C1 broken) and
>>     make your end-users decide what they prefer. If they still prefer
>>     1000 C2's broken, then you need #1.
>>
>>     Tip: Sometimes, taking the square of a weight is a neat trick.
>>     In bin packing, say you got
>>     Solution A with 3 CPU and 3 CPU too little = 3² + 3² = 18
>>     and Solution B with 4 CPU and 2 CPU too little = 4² + 2² = 20
>>     So the second is worse even though they both miss 6 CPU.
>>
>>>
>>>     What is your opinion about both solution.
>>>
>>>     Is one faster then the other ?
>>>
>>>     Is it hard to create a new score definition ?
>>>
>>>     Did anyone ever did this ?
>>>
>>>     -- 
>>>     Patrik Dufresne
>>>
>>>
>>>     _______________________________________________
>>>     rules-users mailing list
>>>     rules-users at lists.jboss.org  <mailto:rules-users at lists.jboss.org>
>>>     https://lists.jboss.org/mailman/listinfo/rules-users
>>
>>     -- 
>>     With kind regards,
>>     Geoffrey De Smet
>>
>>
>>     _______________________________________________
>>     rules-users mailing list
>>     rules-users at lists.jboss.org <mailto:rules-users at lists.jboss.org>
>>     https://lists.jboss.org/mailman/listinfo/rules-users
>>
>>
>>
>>
>> -- 
>> Patrik Dufresne
>>
>>
>> _______________________________________________
>> rules-users mailing list
>> rules-users at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
>
> -- 
> With kind regards,
> Geoffrey De Smet
>
>
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users

-- 
With kind regards,
Geoffrey De Smet

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/rules-users/attachments/20111219/4d429542/attachment.html