A. Guillamón received his Bachelor's degree in mathematics education at the Universidad de Murcia in 1990, and her Ph.D. and Habilitation doctorate degrees from the Mathematics Department of the Universidad de Murcia in 1997. At present he is Associate Professor in the Department of Applied Mathematics and Statistics of the Universidad Politécnica de Cartagena. His main research interests include the the nonparametric estimation, time series analysis, survival analysis and chaos. Antonio Guillamón's address: Universidad Politécnica de Cartagena. Departamento de Matemática Aplicada y Estadística. C/ Doctor Fleming s/n. 30202 Cartagena (Spain).