An Exact Algorithm for the Split-Demand One-Commodity Pickup-and-delivery Travelling Salesman Problem

This paper concerns the problem of designing a route of minimum cost for a capacitated vehicle moving a single commodity between a set of customers. The route must allow two characteristics uncommon in the literature. One characteristic is that a customer may be visited several times. The other characteristic is that a customer may be used as intermediate location to temporarily collect and deliver part of the load of the vehicle. Routes with these characteristics may lead to cost reductions when compared to routes without them. The paper describes a branch-and-cut algorithm based on a relaxation of a model of Mixed Integer Programming. Preliminary computational results on benchmark instances demonstrate the good performance of the algorithm compared with the original model.