A branch-and-price algorithm for the ring/ring problem

Abstract

The ring/ring problem is a hierarchical network design problem that uses a two-level network, in which each level is a ring with limited capacity. It is related to other hierarchical design problems and also to the vehicle routing problem. Rings are used in telecommunications because of their survivability, while hierarchical networks are useful for large networks. We propose an extended integer programming formulation for the problem and a branch-and-price algorithm to solve it. A relaxation of the pricing problem is considered and also primal and pricing heuristics to improve the performance of the algorithm. Computational experiments were conducted on instances derived from the literature and show the hardness to solve instances with high capacity.