Structural Pattern Recognition

recognition. Classic applications are illustrated such as Shaw's picture description language (1969) applied to bubble chamber photographs, and Ledley's chromosome grammar ( 1965). The student with no particular interest in pattern recognition, who nevertheless desires to grasp a quick overview of what formal language theory is all about, could read this chapter. A minimum of preliminary definitions and notation must be waded through before learning about-types of grammars (regular, context-free, context-sensitive), equivalency of grammars, syntaxdirected translations, and deterministic, nondeterministic, and stochastic systems. Higher dimensional grammars are treated in Chapter Three, i.e., those allowing more complex primitive description and interconnection capabilities. Tree, web, plex, and shape grammars are each described with accompanying examples which make the material very easy to absorb. Chapter Four, on recognition and translation of syntactic structures, presents that integral part of formal language theory known as automata theory. The one-to-one correspondences between types of string grammars and automata are presented here, namely finite automation/regular grammar, push-down automaton/context-free grammar, linear-bounded automaton/ context-sensitive grammar, and Turing machine/unrestricted grammar. Quite properly, the authors restrict their attention to the finite and push-down automata used to accept or reject input strings and to automata for tree recognition, since these are the models thus far proved to be most useful for syntactic pattern recognition tasks. Chapter Five introduces stocastic grammars, languages, and recognizers. The material is well covered and brings the reader up to date (1978). As the authors mention, the impact of this theory on syntactic pattern processing has not been thoroughly realized, and references are cited for one interested in pursuing the topic further. The final chapter deals with grammatical inference and exemplifies the principalideas underlying the problem of obtaining a pattern grammar from a set of samples. Again, the material in this chapter is presented in a logical and easy to understand format. By this time the reader is beginning to understand the limitations of the linguistic aspect of syntactic pattern recognition (Reviewer's opinion), and will draw his or her attention to some of the material which came out of this work in the late sixties, which can be described as structural pattern recognition, and which is the topic of the book review which follows.