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Cellular automata in pattern recognition

1993, Information Sciences

Abstract

This paper is a review of recent published work in the application of automata networks as part of a pattern or image recognition system. The principal requirements were to integrate model-based and data-driven approaches within a connectionist framework and to allow full parallelism. In particular, we construct a network of probabilistic cellular automata (PCAs) for iteratively resolving ambiguities and conflicts in pattern recognition. A natural implementation of inductive inference rules in such a network results in a d~amics that is sensitive to nons~metric couplings (s~aptic weights), unlike that of the more common models inspired by statistical physics (e.g., the Boltzmann machine). This, along with full parallelism, means that object recognition must be achieved through the intermediate-time rather than "infinite''-time behavior of the system. Another, more technology-driven, feature includes using local inferences insofar as possible. The framework is translation-invariant, which is natural for image re~gnition. This leads to a different architecture for describing the model from that used in Bayesian inference networks. ' We discuss only bilinear couplings here. Inference rules are often in the form, for example, that feature Q occurs only in conjunction with both features y and 6 in appropriate positions. The most direct way lo incorporate that these would be with trilinear and higher order couplings. An alternative would bc to have hidden units but keep the couplings bilinear (see [281X