t = time index
M = vehicle index
I = supply node
J = intermodal node
I have a variable with (t,M,I,J) index which determines the number of units delivered to a specific node. However, I want to determine the time of delivery of each set of units as a separate variable. Thus, it’s like extracting t from the variables (t,M,I,J). How do I approach this?
Thaank you!