Standard methods for simultaneously inducing the structure and weights
of recurrent neural networks limit every task to an assumed class of
architectures. Such a simplification is necessary since the interactio
ns between network structure and function are not well understood. Evo
lutionary computations, which include genetic algorithms and evolution
ary programming, are population-based search methods that have shown p
romise in many similarly complex tasks. This paper argues that genetic
algorithms are inappropriate for network acquisition and describes an
evolutionary program, called GNARL, that simultaneously acquires both
the structure and weights for recurrent networks. GNARL's empirical a
cquisition method allows for the emergence of complex behaviors and to
pologies that are potentially excluded by the artificial architectural
constraints imposed in standard network induction methods.