1. School of Sciences and Engineering,Tecnologico de Monterrey,Monterrey,México,64849
2. Univcrsité de Technologie de Compiègne,CNRS, Heudiasyc (Heuristics and Diagnosis of Complex Systems),Compiègne Cedex,CS,France,60319-60203
3. CIMAT,Zacatecas,Mexico