In the period following World War II, it began to be recognized that there were a large number of interesting and significant activities which could be classified as multistage decision processes. It was soon seen that the mathematical problems that arose in their study stretched the conventional confines of analysis, and required new methods for their successful treatment. The classical techniques of calculus and the calculus of variations were occasionally valuable and useful in these new areas, but were clearly limited in range and versatility, and were definitely lacking as far as furnishing numerical answers was concerned.The recognition of these facts led to the creation of a number of novel mathematical theories and methods. Among these was the theory of dynamic programming, a new approach based on the use of functional equations and the principle of optimality, with one eye on the potentialities of the burgeoning field of digital computers.