The Neuberger spectra of nonlinear superposition operators in the spaces of sequences

In this paper we consider the nonlinear superposition operator F in lp spaces of sequences, generated by the function f (s; u) = a (s) + un or f (s; u) = a (s)
un First we show that these operators are Frechet differentiable. Then we nd out the Neuberger spectra N (F) of these operators. We compare it with some other nonlinear spectra and indicate some possible applications.