“…To limit the e ective size of a network in order to avoid over tting one can either use additive or subtractive methods or regularization. Additive often called constructive methods start out from a small network and then insert additional units also known as nodes or neurons and connections also known as weights or links until the network can represent the required function Ash, 1989, Fahlman and Lebiere, 1990, Frean, 1990, Gallant, 1986, Hanson, 1989, M ezar and Nadal, 1989, Simon, 1993, Wang et al, 1994, Wynne-Jones, 1991, Zollner et al, 1992. Subtractive often called pruning methods start out from a large network and remove super uous parts until the network can just still represent the required function Le Cun et al, 1989, Finno et al, 1993, Hassibi and Stork, 1993, Levin et al, 1994.…”