[rules-users] Drools Planner: Simple problem having solution with one hard constraint broken. What’s wrong?

[Geoffrey De Smet]

Op 18-12-11 17:26, hevo schreef:
> Found a "solution".
>
> Created an NONE employee that is used in the initial solution instead of
> null.
>
> This way i know which tasks did not find any solution.
>
> Is there a better way?
Currently there is no better way.
Planner 5.3 doesn't support a null planning value for a planning variable.

Vote for this issue:
https://issues.jboss.org/browse/JBRULES-3317
   Planner should support a null planning value
>
> Several users on the user mailing list have run into this, especially 
> for task assignment use cases.
>
> Example use case:
> @PlanningEntity TaskAssignment assigns a Task to a @PlanningVariable 
> Employee
> There are so many Tasks, that's better to not assign some Tasks for now.
>
> Current workaround:
> Make a Employee representing NONE,
> which is the only Employee instance that returns true on employee.isNone()
> and the score rules are written to deal with that.
>
> Technical difficulty to fix:
> The @PlanningVariable(s) of a @PlanningEntity with planning value null 
> are considered to be "uninitialized".
> Partial uninitialized solution detection are fundamental for repeated 
> planning (including real-time planning),
> because the construction heuristics need to detect which parts of the 
> solution to intialize, but not everything because that takes too long.
>



> Regards
>
>
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-- 
With kind regards,
Geoffrey De Smet