  In this work stability results for systems described by coupled Retarded
Functional Differential Equations (RFDEs) and Functional Difference Equations
(FDEs) are presented. The results are based on the observation that the
composite system can be regarded as the feedback interconnection of a subsystem
described by RFDEs and a subsystem described by FDEs. Recent Small-Gain results
and Lyapunov-like characterizations of the Weighted Input-to-Output Stability
property for systems described by RFDEs and FDEs are employed. It is shown that
the stability results provided in this work can be used to study stability for
systems described by neutral functional differential equations and systems
described by hyperbolic partial differential equations.
