1. Centro de Investigacion en Matematicas (CIMAT), Unidad Zacatecas, 98068 Zacatecas, ZAC, Mexico
2. Division de Estudios de Posgrado, Facultad de Ingenieria Electrica, Universidad Michoacana, 58390 Morelia, MICH, Mexico
3. Department of Computer Science and Information Engineering, National Taiwan University, Taipei 106, Taiwan