Originally posted by: S3PU_Yaqing_Tan

Hello everyone,

I am trying to solve a scheduling problem, which need to implement constraints on the interval variables. Under a certain condition, I want them to be a certain number. For example,
when the endOf(a interval variable)<=5, the startOf(the same variable)=4.
I tried several ways, but did not succeed. Thanks a lot!!

Yatsing
#ConstraintProgramming-General
#DecisionOptimization

Originally posted by: SystemAdmin

Hi,

I think, you can use imply (=>) constrants, as:

( endOf(intervalvar <= 5) ) => ( startOf(intervalvar==4) );

#ConstraintProgramming-General
#DecisionOptimization

Originally posted by: S3PU_Yaqing_Tan

Thank you very much. I solved the problem by imply constraint.
#ConstraintProgramming-General
#DecisionOptimization

Originally posted by: SystemAdmin

Hello,
As a possible complement to Mehmet's answer, depending on the particular type of conditions you have, you may be able to use more "global" constraints than a (potentially large) set of composite constraints ( (endOf(a)<=U) => (startOf(a)==V) ). For instance you may look at the "forbidExtent" constraint that prevents an interval variable to overlap a set of fixed time windows. Maybe you can also model your constraints as something like startOf(a)== EXPR ( endOf(a) ) where EXPR is a CP Optimizer expression (example: startOf(a) == 4 * (endOf(a) div 4)).
But of course it is not always possible, that will depend on the particular type of conditions you want to model.

Philippe
#ConstraintProgramming-General
#DecisionOptimization

Originally posted by: S3PU_Yaqing_Tan

thank you. sorry for that i did not read those documents carefully
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#DecisionOptimization