A General Theory of Extremals

Abstract A general concept of extremality is introduced. This concept is shown to be central for a large class of constrained optimization problems. A general set of necessary conditions, which must be satisfied by all solutions of the previously indicated optimization problems. The hypotheses under which these necessary conditions are derived are discussed in detail. The general theory is applied to optimal control problems with restricted phase coordinates, and to an optimal control problems with an unorthodox criterion function.