Luís Gouveia

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The Diameter-Constrained Minimum Spanning Tree Problem seeks a least cost spanning tree subject to a (diameter) bound imposed on the number of edges in the tree between any node pair. A traditional multicommodity flow model with a commodity for every pair of nodes was unable to solve a 20-node and 100-edge problem after one week of computation. We formulate(More)
In this paper we discuss valid inequalities for the directed hop-constrained shortest path problem. We give complete linear characterizations of the hop-constrained path polytope when the maximum number of hops is equal to 2 or 3. We also present a lifted version of the “jump” inequalities introduced by Dahl (Oper. Res. Lett. 25 (1999) 97) and show that(More)
The Rooted Distance-Constrained Minimum Spanning Tree Problem (RDMSTP) is defined as follows: given a graph G = (V,E) with node set V = {0,1,...,n} and edge set E, two integer weights, a cost ce and a delay we associated with each edge e of E, and a natural (time limit) number H, we wish to find a spanning tree T of the graph with minimum total cost and(More)
The Hop-Constrained Minimum Spanning Tree Problem (HMSTP) is a NP-hard problem arising in the design of centralized telecommunication networks with quality of service constraints. We show that the HMSTP is equivalent to a Steiner Tree Problem (STP) in an adequate layered graph. We prove that the directed cut formulation for the STP defined in the layered(More)
In this paper we study the Variable Size Bin Packing Problem (VSBPP) which is a generalization of the Bin Packing Problem where bins of different capacities (and different costs) are available for packing a set of items. The objective is to pack all the items minimizing the total cost associated with the bins. We discuss applications of the VSBPP and(More)