Characterization of extremal controls for infinite dimensional time-varying systems (Q2753208)

Here, linear time-varying, continuous-time and infinite-dimensional control systems are considered. It is generally assumed that the controls are time-varying constrained, and the linear unbounded system operator generates a strongly continuous evolution operator. Using methods taken from functional analysis, attainable sets, extremal controls and normality of the system are discussed. Relationships among these concepts are investigated. Illustrative examples are also presented. Moreover, several remarks and comments on time optimal control problems for infinite control systems are given. Similar problems have been considered by \textit{D. Barcenas} and \textit{J. Diestel} [Quaest. Math. 18, No. 1-3, 185-198 (1995; Zbl 0827.46004)] and by \textit{G. Peichl} and \textit{W. Schappacher} [SIAM J. Control Optimization 24, 1261-1275 (1986; Zbl 0612.49026)].