I'm looking for papers describing different definitions of function in biological systems. Any information would be of help. Thanks in advance, Gustavo Parisi Unidad de Fisicoquimica Universidad Nacional de Quilmes Avenida Calchaqui Km. 23.500 Ex Laboratorio YPF 1888 Florencio Varela, Buenos Aires Argentina E-mail:gustavo at unq.edu.ar Fax: ++ 54-1-255 7176