  In this work characterizations of notions of output stability for uncertain
time-varying systems described by retarded functional differential equations
are provided. Particularly, characterizations by means of Lyapunov and
Razumikhin functions of uniform and non-uniform in time Robust Global
Asymptotic Output Stability and Input-to-Output Stability are given. The
results of this work have been developed for systems with outputs in abstract
normed linear spaces in order to allow outputs with no delay, with discrete or
distributed delay or functional outputs with memory.
