CODEWITHSUNDEEP
droolsoptaplanner
brewphone
brewphone

Reputation: 1366

OptaPlanner, how to minimize the largest sum in DRL

The Task is the PlanningEntity, each task is in a group, groupId is a member of the Task class. What task is in what group is fixed, the groupId is neither PlanningVariable nor PlanningFact. Each task has a duration, it's a shadow variable that is affected by the combination(optimization) of the tasks within the group. Let's call "the sum of task durations in a group" S. S1 for group1, S2 for group2 ... The soft constraint is to minimize the largest S of all the groups. This is not to minimize all S, that's not the goal. I can only think of something like following which is not working. The "index" is the PlanningVariable.

rule "Minimize the largest group duration"
    when
        accumulate(
            accumulate(
                $g: Group(),
                Task(index != null, groupId == g.getId(), $d: duration);
                $s: sum($d)
            )
            $smax: max($s)
        )  
        then
            scoreHolder.addSoftConstraintMatch(kcontext, 1, (-$smax));
    end

Upvotes: 0

Views: 53

Answers (1)

Lukáš Petrovický
Lukáš Petrovický

Reputation: 5702

I am not sure I entirely understand the issue, but something like this should get you the maximum duration:

Task(..., $d: duration)
not Task(..., duration > $d)

$d is now your maximum duration, and you can do anything you like with it.

(Note: You should add the drools tag and possibly also remove the optaplanner one, as this is barely related to OptaPlanner.)

Upvotes: 1

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