Metamorphosis Networks: An Alternative to Constructive Models

Given a set oftraining examples, determining the appropriate number offree parameters is a challenging problem. Constructive learning algorithms attempt to solve this problem automatically by adding hidden units, and therefore free parameters, during learning. Weexplore an alternative class of algorithms-called metamorphosis algorithms-inwhich the number of units is fixed, but the number of free parameters gradually increases during learning. The architecture we investigate is composed of RBF units on a lattice, whichimposes flexible constraints on the parameters of the network. Virtues of this approach include variable subset selection, robustparameter selection, multiresolution processing, and interpolation of sparse training data.