Cyclicity of the shift operator through Bezout identities

TL;DR

This paper investigates the cyclicity of the shift operator on Banach spaces of analytic functions, using corona theorem-based methods to relate the cyclicity of functions under certain inequalities, and applies these results to various function spaces.

Contribution

Introduces a corona theorem-based framework to analyze shift operator cyclicity and provides new sufficient conditions for cyclicity in several analytic function spaces.

Findings

Established a method to transfer cyclicity from one function to another under modulus inequalities.

Reproduced recent cyclicity results in de Branges-Rovnyak, Besov--Dirichlet, and weighted Dirichlet spaces.

Provided new sufficient conditions for function cyclicity in these spaces.

Abstract

In this paper, we study the cyclicity of the shift operator $S$ acting on a Banach space $\X$ of analytic functions on the open unit disc $\D$. We develop a general framework where a method based on a corona theorem can be used to show that if $f,g\in\X$ satisfy $|g(z)|\leq |f(z)|$, for every $z\in\D$, and if $g$ is cyclic, then $f$ is cyclic. We also give sufficient conditions for cyclicity in this context. This enable us to recapture some recent results obtained in de Branges-Rovnayk spaces, in Besov--Dirichlet spaces and in weighted Dirichlet type spaces.