Proceedings of the Annual Meeting of the Cognitive Science Society

We describe a connectionist parsing scheme based on context-free grammar rules. In this scheme we use an updating rule similar to the one used in the Boltzmann machine (Fahlman, Hinton and Sejnowski 1983) and apply simulated annealing. We show that at low temperatures the time average of the visited states at thermal equilibrium represents thte correct parse of the input sentence. In contrast with previously proposed connectionist schemes for natural alnguage processing, this scheme handles the traditionally sequential rule-based parsing in a general manner in the network. Another difference is the use of the computational scheme of the Boltzmann machine. This allows us to formulate general rules for the setting of weights and thresholds in our system. The parsing scheme is built from a small set of connectionist primitives that represent the grammar rules. These primitives are linked together using pairs of computing units that behave like discrete switches. These units are used as binders between concepts represented in collection of rules, and are very useful in the construction of connectionist schemes for any form of rule-based processing.