January 12, 2004
Paul Fuhrmann
Title: On duality in the functional approach to geometric control
We will discuss the functional characterizations of controlled and conditioned invariant subspaces. These use right and left coprime factorizations of the transfer function. When passing on to the characterization of output nulling controlled invariant subspaces and input containing conditioned invariant subspaces and the related observability and reachability subspaces, we would like to get all characterizations in terms of one, say left, coprime factorizations. This can be done, although only using a two step method. These problems arise in observer theory.