New Formulations for the Orienteering Problem

Problems associated with determining optimal routes from one or several depots (origin, home city) to a set of nodes (vertices, cities, customers, locations) are known as routing problems. The Traveling Salesman Problem (TSP) lies at the heart of routing problems. One of the new variants of the TSP is named as TSP with Profits where the traveler must finish its journey within a predetermined time (cost, distance), by optimizing given objective. In this variant of TSP, all cities ought to not to be visited. The Orienteering Problem (OP) is the most studied case of TSP with Profits which comes from an outdoor sport played on mountains. In OP, traveler gets a gain (profit, reward) from the visited node and the objective is to maximize the total gain that the traveler collects during the predetermined time. The OP is also named as selective TSP. In this paper, we present two polynomial size formulations for OP. The performance of our proposed formulations is tested on benchmark instances. We solved the benchmark problems from the literature via CPLEX 12.5 by using the proposed formulations and existing formulation. The computational experiments demonstrate that; (1) both of the new formulations over estimates the existing one; and (2) the proposed formulations are capable of solving all the benchmark instances that were solved by using special heuristics so far. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license