4.4. Constraints. The first series of constraints is order to ensure that the requirements of capitalized VRP are fulfilled. We first formulate the constraints for the outbound VRP as follows, and the constraints for the inbound VRP can be formulated in a similar way:
(1) the load must be less than the vehicle capacity, as shownin
(2) each customer must be served by one and only one route,asdefinedin
(3) if the customer