This book provides a thorough introduction to optimal control theory for nonlinear systems. … The book is enhanced by the inclusion of many examples, which are analyzed in detail using Pontryagin’s principle. … An important feature of the book is its systematic use of a relaxed control formulation of optimal control problems. …—From the Foreword by Wendell Fleming… more than a very useful research account and a handy reference to users of the theory-they also make it a pleasant and helpful study opportunity to students and other newcomers to the theory of optimal control.—Zvi Artstein, in Mathematical Reviews