José Luis Santos
University of Coimbra
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Featured researches published by José Luis Santos.
International Journal of Foundations of Computer Science | 1999
Ernesto de Queirós Vieira Martins; Marta M. B. Pascoal; José Luis Santos
The shortest path problem is a classical network problem that has been extensively studied. The problem of determining not only the shortest path, but also listing the K shortest paths (for a given integer K>1) is also a classical one but has not been studied so intensively, despite its obvious practical interest. Two different types of problems are usually considered: the unconstrained and the constrained K shortest paths problem. While in the former no restriction in considered in the definition of a path, in the constrained K shortest paths problem all the paths have to satisfy some condition – for example, to be loopless. In this paper new algorithms are proposed for the uncontrained problem, which compute a super set of the K shortest paths. It is also shown that ranking loopless paths does not hold in general the Optimality Principle and how the proposed algorithms for the unconstrained problem can be adapted for ranking loopless paths.
Operations Research Letters | 1997
Ernesto de Queirós Vieira Martins; José Luis Santos
The quickest path problem arises when transmitting a given amount of data between two given nodes of a network, a lead time and a capacity (per unit of time) being assigned to each arc in the network. In this paper the problem is regarded as a bicriteria path problem, allowing the use of a very efficient algorithm which solves the quickest path problem for all possible values of the amount of data that has to be transmitted.
Computers & Operations Research | 2003
M. Eugénia V. Captivo; João C. N. Clímaco; José Rui Figueira; Ernesto de Queirós Vieira Martins; José Luis Santos
This paper examines the performances of a new labeling algorithm to find all the efficient paths (or non-dominated evaluation vectors) of the bicriteria 0-1 knapsack problem. To our knowledge this is the first time a bicriteria 0-1 knapsack is solved taking advantage of its previous conversion into a bicriteria shortest path problem over an acyclic network. Computational experiments and results are also presented regarding bicriteria instances of up to 900 items. The algorithm is very efficient for the hard bicriteria 0-1 knapsack instances considered in the paper.
Networks | 2003
José Manuel Paixão; Ernesto de Queirós Vieira Martins; Mário S. Rosa; José Luis Santos
The multiobjective shortest path problem (MSPP) consists of finding the best nondominated path linking two specified nodes in a network where k > 1 different criteria are considered for the arc costs. Solving the MSPP implies determining all the nondominated paths; there may be many such paths, making the selection process a very hard task to accomplish. A traditional way of dealing with such a difficulty is using a utility function where the parameters are aggregated with different weights. In this work, an alternative utility function based on the norm value associated with each path is considered. Two algorithms for solving the minimum-cost norm path problem are then proposed and some computational results are presented.
Journal of Mathematical Chemistry | 2013
M. Patrício; José Luis Santos; F. Patrício; A. J. C. Varandas
The use of the theory of splines to approximate the potential energy surface in molecular dynamics is examined. It is envisaged that such an approximation should be able to accurately capture the potentials’ behavior and be computationally cost effective, both for one-dimensional and
Discrete Mathematics | 2018
Gonçalo Gutierres; Ricardo Mamede; José Luis Santos
Computers & Operations Research | 2018
José Luis Santos; Luigi Di Puglia Pugliese; Francesca Guerriero
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International Journal of Foundations of Computer Science | 1998
Marta M. B. Pascoal; José Luis Santos
Archive | 1999
Marta M. B. Pascoal; José Luis Santos
-dimensional problems with
Archive | 1999
Marta M. B. Pascoal; José Luis Santos