VRP: Constraining the difference of 2 cumul variables

[rishab9750]

I am working on a VRP, where I need to constrain the difference between two cumulative variables.

In particular, the model contains a series of Pickup and Dropoff node pairs. The model also has a time_dimension. Each pickup and dropoff node have a cumulative variable associated with the time_dimension.

I need to constrain the following:

time_dimesion_cumvar_at_dropoff - time_dimesion_cumvar_at_pickup <= allowed_transit_time

allowed_transit_time is a constant

I'm aware of how to set a constraint on a single cumulative variable, e.g. constraining time_dimesion_cumvar_at_dropoff to occur within some time window. However, my goal is to constraint the difference between two different cumulative variables. How can this be achieved?

[vuongdanghuy]

May be you could try something like this.

IntVar* difference = solver.MakeDifference(dimension.CumulVar(dropoff), dimension.CumulVar(pickup)).Var();
solver.AddConstraint(solver.MakeLessOrEqual(difference, allowed_transit_time));

[rishab9750]

Thank you,
I will try it out once.