“…• the "modified follow the leader" (Chicco et al, 2003a;-,2003b;-, 2006), • the self-organizing map (Beccali et al, 2004;Chicco et al, 2004;-, 2006 ;Figueiredo et al, 2003;Lamedica et al 1996;Verdu et al, 2003), • the k-means Figueiredo et al, 2003), • the average and Ward hierarchical methods (Chicco et al, 2004;-, 2006;Gerber et al, 2003) and • the fuzzy k-means (Chicco et al, 2004;-, 2006;Gerber et al, 2003;). All the above methods generally belong to pattern recognition techniques (Theodoridis & Koutroumbas, 1999).…”