The Journal of the Indian Mathematical Society

Nand Lal ¹, Gyan Prakash Tripathi ¹

Affiliations
1 Department of Mathematics, Banaras Hindu University, Varanasi-221 005, IN

Abstract

Let l² be the Hilbert space of all square summable sequences of complex numbers under the standard inner product on it and C_Φ be a composition operator on l² induced by a function Φ on N into itself. In this paper we have obtained a necessary and sufficient condition for a composition operator C_Φ to be a sum of a normal and a compact operator, explicitly in terms of Φ.

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