1. Department of Statistics and Operations Research, University of Granada, Granada, Spain
2. I.E.S. Castillo de la Yedra, Jaén, Spain
3. Institute of Information Engineering, Automation and Mathematics, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Bratislava, Slovak Republic
4. Departamento de Informática e Matemática Aplicada, Universidade Federal do Rio Grande do Norte, Natal, Brazil
5. Center of Comoutational Sciences, Universidade Federal de Rio Grande, Rio Grande, Brazil
6. Departamento de Estadística, Informática y Matemáticas, Universidad Pública de Navarra, Pamplona, Spain