1. A method for implementing production rules of an expert system using a neural network, said method comprising the steps of: (a) defining a plurality of inputs and system outputs for said expert system; (b) defining at least one group of production rules which define a relationship between one of said system outputs and at least one of said plurality of inputs; (c) defining said neural network, said neural network having at least one network output, said neural network being responsive to said at least one of said plurality of inputs corresponding to said at least one group of production rules, and said neural network comprising a plurality of neurons; (d) computing the weights of said neural network using training examples derived from the at least one group of production rules; (e) expressing said neural network by a polynomial expansion: and (f) computing said at least one network output by substituting said at least one of said plurality of inputs into said polynomial expansion; wherein said one of said system outputs is based on said at least one network output.