sub- mitted by Waltz and Sejnowski, intended to provoke responses from them. I. What is a "connectionist" modeff The basic metaphor involves a finite set of nodes inter- connected by a finite set of directed arcs. Each node trans- mits on its output arcs some function of what it receives on its input arcs; these transfer functions are usually described parametrically, for instance in terms of a linear combination of the inputs composed with some nonlinear threshold-like function; the transfer function may involve a random vari- able. A subset of the nodes (or arcs) are designated as inputs and/or outputs, whose values are supplied or used by the "environment". "Time" is generally quantized and treated in an idealized way, as if all connections involved a transmission delay ex- actly equal...

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