Given a central depot, the Vehicle Routing Problem (VRP) calls for the determination
of the optimal set of routes to be performed by a fleet of vehicles, in order to satisfy the
demand of a given set of customers. Several important variants of this basic problem were
extensively studied in the literature (see, e.g., Toth and Vigo (2002b) for a recent review).
In particular, the symmetrical Capacitated VRP (CVRP) is the well-known variant of the
VRP where all vehicles are identical and have a maximum loading capacity, and all the
arcs in the graph representing the underlying road network can be travelled along both
directions, producing the same cost