Regular and Strongly Regular Time and Norm Optimal Controls
Fattorini, H. O.
Pontryagin’s maximum principle in its infinite dimensional version provides (separate) necessary and sufficient conditions for both time and norm optimality for the system y′ = Ay + u (A the infinitesimal generator of a strongly continuous semigroup). Among controls that satisfy the maximum principle, a smoothness distinction can be defined in terms of smoothness of the final value of the costate. This paper addresses some issues related to this distinction.