On the essential norms of Toeplitz operators on abstract Hardy spaces built upon Banach function spaces

Fuente: arXiv
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Autori principali: Karlovych, Oleksiy, Shargorodsky, Eugene
Natura: Preprint
Pubblicazione: 2024
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author Karlovych, Oleksiy
Shargorodsky, Eugene
author_facet Karlovych, Oleksiy
Shargorodsky, Eugene
contents Let $X$ be a Banach function space over the unit circle such that the Riesz projection $P$ is bounded on $X$ and let $H[X]$ be the abstract Hardy space built upon $X$. We show that the essential norm of the Toeplitz operator $T(a):H[X]\to H[X]$ coincides with $\|a\|_{L^\infty}$ for every $a\in C+H^\infty$ if and only if the essential norm of the backward shift operator $T(\mathbf{e}_{-1}):H[X]\to H[X]$ is equal to one, where $\mathbf{e}_{-1}(z)=z^{-1}$. This result extends an observation by Böttcher, Krupnik, and Silbermann for the case of classical Hardy spaces.
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id arxiv_https___arxiv_org_abs_2408_13907
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publishDate 2024
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spellingShingle On the essential norms of Toeplitz operators on abstract Hardy spaces built upon Banach function spaces
Karlovych, Oleksiy
Shargorodsky, Eugene
Functional Analysis
Let $X$ be a Banach function space over the unit circle such that the Riesz projection $P$ is bounded on $X$ and let $H[X]$ be the abstract Hardy space built upon $X$. We show that the essential norm of the Toeplitz operator $T(a):H[X]\to H[X]$ coincides with $\|a\|_{L^\infty}$ for every $a\in C+H^\infty$ if and only if the essential norm of the backward shift operator $T(\mathbf{e}_{-1}):H[X]\to H[X]$ is equal to one, where $\mathbf{e}_{-1}(z)=z^{-1}$. This result extends an observation by Böttcher, Krupnik, and Silbermann for the case of classical Hardy spaces.
title On the essential norms of Toeplitz operators on abstract Hardy spaces built upon Banach function spaces
topic Functional Analysis
url https://arxiv.org/abs/2408.13907