In this paper, we prove an extension of the Helson–Lowdenslager theorem for L2(T) for sub - Hilbert spaces under certain axioms. Furthermore, we provide an alternate proof of characterization of shift invariant sub-Hilbert spaces contained in H2(D) satisfying similar axioms. © 2021, Tusi Mathematical Research Group (TMRG).

Niteesh Sahni

Mathematics

(SoNS) School of Natural Sciences

Anand J.

Srivastava S.

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