> Unless you don't have a <localSearch> configuration of course.
Indeed, somewhere during my testing and trying to figure out what the use of each configuration part is, I stripped out the local search part.
Never noticed it because I always got zero score so far...

Ok, on to localSearch.

Thanks!

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From: Geoffrey De Smet <ge0ffrey.spam@gmail.com>
To: Rules Users List <rules-users@lists.jboss.org>
Sent: Tuesday, January 8, 2013 11:29 AM
Subject: Re: [rules-users] Purpose of difficultyWeightFactoryClass in @PlanningEntity annotation.


Op 08-01-13 11:12, Geoffrey De Smet schreef:

Op 08-01-13 10:23, Michiel Vermandel schreef:
Many thanks Geoffrey and Reinis for the advice and directions.

One more question: is it possible that the solver stops in 2.8 seconds with a negative score solution even the termination config says hardscore 0 OR 3600 seconds?
No, presuming that that's a negative hardscore.
Unless you don't have a <localSearch> configuration of course.
The <constructionHeuristics> don't run forever: they stop fairly fast.
Giving them more time is pointless.
See manual section "Termination" and "SolverPhase".

Does Solver.solve() throw an exception?
If not, what does the logging say? If that doesn't say anything, enable INFO or DEBUG logging (see manual).
Or do I have something wrong?
Or is it the local search that will be cut off?

Thanks

Michiel

 
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From: Geoffrey De Smet <ge0ffrey.spam@gmail.com>
To: Rules Users List <rules-users@lists.jboss.org>
Sent: Tuesday, January 8, 2013 8:32 AM
Subject: Re: [rules-users] Purpose of difficultyWeightFactoryClass in @PlanningEntity annotation.

Some extra info, on top of Reinis's excellent advice:
Take a look at this image:
https://hudson.jboss.org/hudson/view/Drools%20jBPM/job/drools-planner/lastSuccessfulBuild/artifact/drools-planner-docs/target/docbook/publish/en-US/html_single/images/Chapter-Optimization_algorithms/generalPhaseSequence.png
As the image shows, <constructionHeuristics> don't result into an
optimal solution.
You need to do <localSearch> after it too.
Oversimplifiedly speaking, Construction heuristics are fast and brittle,
Local Search is slow and robust.

Only construction heuristics *_FIT_DECREASING use
difficultyWeightFactoryClass.
By giving a better estimation of the planning difficulty of a entity,
the construction heuristics perform better and Local Search has to do
less work for the same result.

Read these sections in the manual:
Without difficultyWeight:
http://docs.jboss.org/drools/release/5.5.0.Final/drools-planner-docs/html_single/index.html#d0e6076
With difficultyWeight (the result of FFD is statistically better than FF):
http://docs.jboss.org/drools/release/5.5.0.Final/drools-planner-docs/html_single/index.html#d0e6126
DifficultyWeight details:
http://docs.jboss.org/drools/release/5.5.0.Final/drools-planner-docs/html_single/index.html#planningEntityDifficulty

Op 07-01-13 22:04, Reinis schreef:
> Hello Michiel,
>
>  >I thought it was used to indicate which PlanningEntities to handle
> first in order to get faster to a solution.
>
> To my understanding this is not quite true. DifficultyWeight defines
> what Entities will likely be more difficult to plan, period.
>
> What is actually DONE with this statement (of difficulty) is decided by
> meta heuristics algorithm and/or by different selectors (not sure about
> this one though). What I am saying
> - difficulty weight just says "yo, dude, this planning entity is
> hard/easy to plan"
> - meta heuristics algorithm (also construction heuristics) then say "oh
> great, then I start with easy ones" or "oh dude, then I get first down
> to hard ones" or even "nice, but I don't give a damn about difficulty
> whatdoyaknow"
>
> *assumption mode on*
> The reason why you all of the sudden get negative hard score MIGHT be
> that the "right" entities are falling out of the selection. And this is
> controlled by meta heuristics algorithm.
>
> As I understand all the meta heuristics magic - it can solve problems
> with the space of 10^650 because... it cheats! Yes, it does not evaluate
> ALL of the possible values (entities or planning variables) but selects
> a subset of those (the ones likely to yield a solution).
>
> And one more thought - changing difficulty weight calculation (in
> factory) should normaly NOT have such a drastic influence on score (up
> to now I used difficulty weight calcs to increase performance). So I am
> suggesting here that the issue MAY lay some other place (typical would
> be local optima).
> *assumption mode off*
>
> In drools planner docs there is some decent information on selection of
> stuff. If I may suggest, start with construction heuristic types and
> check out the docs where it says what BEST_FIT or, respectively,
> BEST_FIT_DECREASING does.
>
> I hope I could at least give you couple of ideas on where to proceed
> with the issue.
>
> br
> Reinis
>
> On 01/07/2013 09:26 PM, Michiel Vermandel wrote:
>> Hi,
>>
>> I am struggling with the purpose of difficultyWeightFactoryClass in
>> the @PlanningEntity annotation.
>>
>> I thought it was used to indicate which PlanningEntities to handle
>> first in order to get faster to a solution.
>> Though it seems that it also has impact on whether or not to get to a
>> zero-hardscore solution.
>> I mean I have a testcase that resolves to a zero-hardscore solution.
>> Then I change something small in how the difficultyWeightFactoryClass
>> calculates the weight and all the sudden I get a negative-hardscore
>> solution.
>> I thought it would still get to the same zero-hardscore solution but
>> in a shorter solving time.
>>
>> My solver termination is as follows:
>>
>> <termination>
>> <terminationCompositionStyle>OR</terminationCompositionStyle>
>> <maximumSecondsSpend>3600</maximumSecondsSpend>
>> <scoreAttained>0hard/0soft</scoreAttained>
>>      </termination>
>>
>> and constructionHeuristic:
>>
>> <constructionHeuristic>
>> <constructionHeuristicType>BEST_FIT_DECREASING</constructionHeuristicType>
>>      </constructionHeuristic>
>>
>> I do not reach a zero-hardscore and the time spent is about 2.8 seconds...
>>
>> If I read the best solution I get:
>> .isEveryProblemFactChangeProcessed(): true
>> .isTerminateEarly(): false
>>
>> Any idea why I do not get a zero-hardscore solution anymore when only
>> making a small change to the difficultyWeightFactoryClass logic?
>>
>> Thanks
>>
>> Michiel.
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