We study the hub location and routing problem where we jointly decide on the location of hubs, the allocation of nodes to hubs, and the routing among the nodes allocated to the same hubs, with the aim of minimizing the total transportation cost. Each hub has one vehicle that visits all the nodes assigned to it on a cycle. We propose a mixed integer programming formulation for this problem and s...

L.A. Wolsey * A class of strong valid inequalities is described for the single-item uncapacitated economic lot-sizing problem with start-up costs. It is shown that these inequalities yield a complete polyhedral characterization of the problem. The corresponding separation problem is formulated as a shortest path problem. Finally, a reformulation as a plant location problem is shown to imply the...

We consider the two-level uncapacitated facility location problem with singleassignment constraints (TUFLP-S), a problem that arises in industrial applications in freight transportation and telecommunications. We present a new Lagrangian relaxation approach for the TUFLP-S, based on solving a single-level uncapacitated facility location problem (UFLP) as the Lagrangian subproblem. We also devel...

We consider the hub location problem, where p hubs are chosen from a given set of nodes, each nonhub node is connected to exactly one hub and each hub is connected to a central hub. Links are installed on the arcs of the resulting network to route the traffic. The aim is to find the hub locations and the connections to minimize the link installation cost. We propose two formulations and a heuri...

The p-median problem is a classic discrete location with numerous applications. It aims to open p sites while minimizing the sum of distances each client its nearest site. We study Benders decomposition most efficient formulation in literature. show that cuts can be separated linear time. reformulation leads compact for problem. implement two-phase algorithm outperforms state-of-the-art methods...

Multi-objective capacitated multiple allocation hub location problem (MOCMAHLP) is a variation of classic problem, which deals with network design, considering both the number and hubs connections between spokes, as well routing flow on network. In this study, we offer two meta-heuristic approaches based non-dominated sorting genetic algorithm (NSGA-II) archived multi-objective simulated anneal...

Available online 9 December 2008