[rules-users] Problem with chained planning variables

[Juan Ignacio Barisich]

Hi again. The problem was a score corruption issue. When I activate de mode
debug:

<environmentMode>DEBUG</environmentMode>

some exceptions appear, like:

java.lang.IllegalStateException: Score corruption: the workingScore
(0hard/-35soft) is not the uncorruptedScore (0hard/-31soft)...

I had to fix some rules, but I cant fix one in particular. When I looking
at the example rules (with chained variables), the most are based only on
the previous item of the chain, e.g.:

rule "distanceToPreviousAppearance"
    when
        $visit : Visit(previousAppearance != null,
$distanceToPreviousAppearance : distanceToPreviousAppearance)
    then
        insertLogical(new
IntConstraintOccurrence("distanceToPreviousAppearance",
ConstraintType.NEGATIVE_SOFT,
                $distanceToPreviousAppearance,
                $visit));
end

When optaplanner do the moves while planning, the IntConstraintOccurrence
works ok, because the drools engine "retracts" the IntConstraintOccurrence
facts properly. But, in my case the score caculation must be based on the
entire chain. That is:

I have some Doctors, and Cases (medical cases). I have to write a score
rule for consider the delay of attention. So, each Case has a request time
(when the patient calls) and a approximate duration of the case (in
minutes). So, if I have the next chain:

Doctor1 -> Case1 (requestTime:8am, duration:60minutes) ->
Case2(requestTime:8:30am,
duration:30minutes) -> Case3(requestTime:8:30am, duration:30minutes)

the delay time for this solution must be: 30min(for Case2) + 60min(for
Case3) = 90 minutes. As yo see, you can't calculate the delay of one Case
only as from its previous on the chain.

I must to implement a rule to calculate a soft constraint, to achive
less-delay plannings. My first attempt looks like:

rule "delaySC"
    when
        $case : Case( )
        eval($case.getDelay() > 0)
    then
       insertLogical(new IntConstraintOccurrence("delaySC",
ConstraintType.NEGATIVE_SOFT,
                $case.getDelay(), $case));
end

I have to do an eval(), because a delay can not be negative. The getDelay()
method process the chain and calculates it. The problem of this attempt, an
other similars, is when the optaplanner engine do the moves while solving,
the IntConstraintOccurrence is not retracted and the score corruption
exception appears.

The question is: ¿have you know similar scenarios, in which you have to
process the entire chain to calculate the score of a solution? ¿is there a
way to solve this?

Thanks

Regards







2013/9/2 Juan Ignacio Barisich <juan.barisich at gmail.com>

> Hi everybody.
> I have a problem with chained planning variables.
> I'm using optaplanner 5.5.0.Final.
> I have a planning entity like:
>
> @PlanningEntity()
> public class Case implements Chained {
>     private Chained previous;
>     @PlanningVariable(chained = true)
>     @ValueRanges({
>             @ValueRange(type = ValueRangeType.FROM_SOLUTION_PROPERTY,
> solutionProperty = "doctors"),
>             @ValueRange(type = ValueRangeType.FROM_SOLUTION_PROPERTY,
> solutionProperty = "cases", excludeUninitializedPlanningEntity = true) })
>     public Chained getPrevious() {
>         return previous;
>     }
> }
>
> A fact class:
> public class Doctor implements Chained {
>    ...
> }
>
> An a solution class:
> public class Plan extends implements Solution<HardAndSoftScore> {
>     private List<Doctor> doctors;
>     private List<Case> cases;
>     private HardAndSoftScore score;
>
>     @PlanningEntityCollectionProperty
>     public List<Case> getCases() {
>         return cases;
>     }
>
>     public Collection<? extends Object> getProblemFacts() {
>         return new ArrayList<Doctor>(doctors);
>     }
> }
>
> The equals / hashCode / clone methods are inspired on the
> TravelingSalesmanTour example.
>
> I want that Optaplanner generates chains like:
> DoctorA <- Case1 <- Case2
> DoctorB <- Case3
>
> This model tries to represent a list of Cases assigned to each Doctor.
> Suppose I build a solution like:
>
> Plan plan = new Plan();
> plan.setDoctors(DoctorA, DoctorB); //pseudo-code
> plan.setCases(Case1, Case2); //pseudo-code
>
> Then I build a solver:
> Solver solver = getSolverFactory().buildSolver();
> solver.setPlanningProblem(plan);
> solver.solve();
> Plan bestPlan = (Plan) solver.getBestSolution();
>
> The problem is that, Optaplanner is not testing all the posible
> combinations of chains. I mean, suppose that we know that the better
> solution (based on the scoring rules) is:
> DoctorA
> DoctorB <- Case1 <- Case2
>
> But Optaplanner seems to test only chains with DoctorA, so the result of
> calling getBestSolution() is:
> DoctorA <- Case1 <- Case2
>
> I guess that Optaplanner only test chains whit DoctorA, becouse it logs
> lines like:
> ...
> DEBUG: org.drools.planner.core.localsearch.DefaultLocalSearchSolverPhase
> -     Step index (1), time spend (20002), score (1hard/2soft),     best
> score (1hard/2soft), accepted/selected move count (0/58187) for picked step
> (Case [id=2, previous=Doctor [id=1]] => Case [id=1, previous=Case [id=2,
> previous=Doctor [id=1]]]).
> ...
> That is, no lines whith "DoctorB" are logged.
> If the doctor list is inverted, the same problem happen (the DoctorA is no
> processed). That is:
>
> Plan plan = new Plan();
> plan.setDoctors(DoctorB, DoctorA); //pseudo-code
> plan.setCases(Case1, Case2); //pseudo-code
> Solver solver = getSolverFactory().buildSolver();
> solver.setPlanningProblem(plan);
> solver.solve(); // DoctorA is not part of chains
>
>
> I guess the problem is on the solver configuration, specifically on the
> localSearch configuration:
>
> <localSearch>
>         <unionMoveSelector>
>             <changeMoveSelector>
>                 <valueSelector/>
>             </changeMoveSelector>
>             <swapMoveSelector />
>             <subChainChangeMoveSelector>
>                 <selectReversingMoveToo>true</selectReversingMoveToo>
>             </subChainChangeMoveSelector>
>             <subChainSwapMoveSelector>
>                 <selectReversingMoveToo>true</selectReversingMoveToo>
>             </subChainSwapMoveSelector>
>         </unionMoveSelector>
>         <acceptor>
>             <planningEntityTabuSize>9</planningEntityTabuSize>
>         </acceptor>
>         <forager>
>             <minimalAcceptedSelection>2000</minimalAcceptedSelection>
>         </forager>
>     </localSearch>
>
> I tried some alternatives to this configuration, but with no success.
>
> Do you know what I am doing wrong?
>
> Thanks a lot.
>
> Regards
>
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