State estimation for infinite-dimensional systems

AbstractWe consider the problem of determining state from input-output data, for systems with state space of infinite dimension.In Sections 1–4 we consider some concrete examples of systems governed by partial differential operators and we show what sort of difficulties one has to contend with when controls or observations are boundary values. In Section 5 we consider the problems in a more general and abstract setting.Methods used in Sections 1–4 and in Section 5 are “dual” and the paper is organized in such a way that it is also possible to start with Section 5 and proceed next to Sections 1–4