Affiliation: | aDepartment of Computer Engineering and Systems Science, University of Pavia, Via Ferrata 1, 27100 Pavia, Italy bDepartment of Mathematics, University of Pavia, Via Ferrata 1, 27100 Pavia, Italy cDepartment of Mathematics, University of Oviedo, University Technical School of Industrial Engineers, Viesques Campus, 33203 Gijón, Spain dDepartment of Statistics and O.R., University of Oviedo, University Technical School of Industrial Engineers, Viesques Campus, 33203 Gijón, Spain |