1. Institute of Intelligent Systems and Numerical Applications in Engineering (SIANI); University of Las Palmas de Gran Canaria; 35017 Las Palmas de Gran Canaria Spain
2. Department of Computer Science; Multimedia, and Telecommunication; IN3 - Open University of Catalonia; 08018 Barcelona Spain
3. Department of Statistics and Operations Research; Public University of Navarre; 31006 Pamplona Spain