Fundamentality of ridge functions

Original Contribution: Multilayer feedforward networks with a nonpolynomial activation function can approximate any function

Neural Networks

On best approximation of classes by radial functions

Journal of Approximation Theory

Approximation by ridge function fields over compact sets

Journal of Approximation Theory

Characterization of an extremal sum of ridge functions

Journal of Computational and Applied Mathematics

On the representation by linear superpositions

Journal of Approximation Theory