I'm working on a flexible job shop scheduling problem in CP and I'm having trouble defining a constraint. I'm trying to set a constraint for ( operations o and o' should always be performed on the same machine ) even though that could be one of several flexible machines. Has anyone got suggestions for efficient ways to express this in CP syntax?
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2 replies Latest Post - 2012-12-10T01:20:52Z by SystemAdmin
Pinned topic Flexible job shop - process tasks on the same machine
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Updated on 2012-12-10T01:20:52Z at 2012-12-10T01:20:52Z by SystemAdmin
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Re: Flexible job shop - process tasks on the same machine2012-12-07T10:33:43Z in response to SystemAdminHi
I suppose your are working with an interval variable based model. You have creating an alternative constraint to express the choice of the shop for each operations in a job.
The presence constraint on the interval variables (operation, shop) is also an integer expression (see meta constraint in CP Optimizer in the documentation)
Logical execution rules between such optional interval variables are stated using constraint on constraint (or operator of OPL), integer constraint (e.g presemceOf(a) = presenceOf(b) state that both interval will be present or absent simultatneously or for more sophisticated rules please refer to allowedAssignemnt and forbiddenAssignemnet constraints on integer expression.
Hope that helps