Coding and system theory: a control engineer feeds back

In 1969, James L. Massey and the author expressed the conviction that an interdisciplinary approach to the theories of automatic control and of error-correcting codes could, because of common algebraic content, result in advances in each field at that time. They pointed out that the cross-contributions promised to come from the unified study of the relatively general and abstract viewpoint of control and of the specific and intricate techniques of coding. Having spent about eighteen months doing preliminary studies, the authors had found evidence of interdisciplinary interest on the part, of groups specializing in adaptive processes, switching and automata theory, coding theory, information theory, circuit and system theory, and automatic control theory, together with an interest by electrical engineers in general. Encouraged by the interest and the preliminary results, Massey and Sain proposed formal investigations of this interdisciplinary frontier, to formulate problems in coding as general problems in dynamical system theory, to formulate problems in control as problems in coding theory, to determine thereby new solutions and techniques in both areas, to establish the significance of these solutions and techniques, to subsequently merge known results in coding and control theories, and to isolate during the progress of the work any basic differences between the two areas. Looking back upon those early goals, it is certainly true that some of them have seen a great deal of progress over the years, and others are yet today in progress. The primary goal of this paper is to discuss the early results; and the focus is placed upon the first five years