An extension of Redheffer's theorem for time-varying systems

It is well known that the Redheffer theorem is a key tool in the technical machinery of the H/sub /spl infin// theory. The time-varying version of this theorem has been considered first in Ravi et al. (1991). In the present paper we generalise Redheffer's theorem for time-varying systems by considering relaxed assumptions. More precisely, the exponential stability assumption is relaxed to that of exponential dichotomy while the stability and detectability conditions imposed on the closed loop system are removed.