Symbolic analysis of switching circuits

IN CONTROL and protective circuits of complex electriC systems intricate interconnections of relay contacts and switches frequently are necessary. Examples of such circuits may be found in automatic telephone exchanges, industrial motor-control equipment, and in almost any circuits designed to perform complex operations automatically. In this paper^∗ some of the properties of such networks are analyzed mathematically, and particular attention is given to network synthesis. If the circuit characteristics are given and the circuit incorporating those characteristics is to be found, the solution is not unique, and methods of finding those particular circuits having the minimum number of relay contacts and switch blades are described. Methods for finding any number of circuits equivalent in all operating characteristics to a given circuit also are outlined.