Dr. George Friedman is indisputably the father of the very powerful methods of Constraint Theory. Indeed, in 1970 it received major commendation by the IEEE: Dr. Friedman's pioneering research was awarded the highly prestigious W.R.G. Baker prize as the most significant published research contribution among thousands of published research papers. This speaks volumes for Dr. Friedman's contribution. --Cornelius T. Leondes, UCLA Friedman's accomplishment represents engineering at its finest. The choice of subject matter must be honored by the experience gained in his many years of high-level service in the company now known as Northrop-Grumman. The credibility of the theory rests upon the formal proofs which are interspersed among the illuminating hypothetical dialog sequences between manager and analyst, which bring out distinctions that the organization must face, en route to accepting Friedman's work as essential to achieve quality control in developing and applying large models. --John N. Warfield