Which hyponormal block Toeplitz operators are either normal or analytic?

Fuente: arXiv
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Autores principales: Zhu, Senhua, Lu, Yufeng, Zu, Chao
Formato: Preprint
Publicado: 2023
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author Zhu, Senhua
Lu, Yufeng
Zu, Chao
author_facet Zhu, Senhua
Lu, Yufeng
Zu, Chao
contents In this paper, we continue Curto-Hwang-Lee's work to study the connection between hyponormality and subnormality for block Toeplitz operators acting on the vector-valued Hardy space of the unit circle. Curto-Hwang-Lee's work focuses primarily on hyponormality and subnormality of block Toeplitz operators with rational symbols. By studying the greatest common divisor of matrix-valued inner functions and the ``weak" commutativity of matrix-valued inner functions, we extended Curto-Hwang-Lee's result to block Toeplitz operators with symbols of bounded type. More precisely, we proved that if $Ψ,Ψ^{\ast}$ are matrix-valued functions of bounded type and the inner part of $Ψ$ of Douglas-Shapiro-Shields factorization is a scalar inner function, then every hyponormal Toeplitz operator $T_Ψ$ whose square is also hyponormal must be either normal or analytic.
format Preprint
id arxiv_https___arxiv_org_abs_2308_01373
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Which hyponormal block Toeplitz operators are either normal or analytic?
Zhu, Senhua
Lu, Yufeng
Zu, Chao
Functional Analysis
Primary 47B35, 46E40, Secondary 47B20
In this paper, we continue Curto-Hwang-Lee's work to study the connection between hyponormality and subnormality for block Toeplitz operators acting on the vector-valued Hardy space of the unit circle. Curto-Hwang-Lee's work focuses primarily on hyponormality and subnormality of block Toeplitz operators with rational symbols. By studying the greatest common divisor of matrix-valued inner functions and the ``weak" commutativity of matrix-valued inner functions, we extended Curto-Hwang-Lee's result to block Toeplitz operators with symbols of bounded type. More precisely, we proved that if $Ψ,Ψ^{\ast}$ are matrix-valued functions of bounded type and the inner part of $Ψ$ of Douglas-Shapiro-Shields factorization is a scalar inner function, then every hyponormal Toeplitz operator $T_Ψ$ whose square is also hyponormal must be either normal or analytic.
title Which hyponormal block Toeplitz operators are either normal or analytic?
topic Functional Analysis
Primary 47B35, 46E40, Secondary 47B20
url https://arxiv.org/abs/2308.01373