On Quasinormality of compact perturbations of the isometries

Fuente: arXiv
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Main Author: Das, Susmita
Format: Preprint
Published: 2025
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author Das, Susmita
author_facet Das, Susmita
contents We study the compact perturbations of an isometry on a separable Hilbert space and provide a complete characterization of when they are quasinormal. Based on that, we present a complete classification for a rank-one perturbation of a unilateral shift of finite multiplicity to be quasinormal in the setting of the Hardy space. The result can also be generalized for a separable Hilbert space. As an application, we provide a complete characterization for quasinormality of a rank-one perturbation of the Hardy shift.
format Preprint
id arxiv_https___arxiv_org_abs_2512_06967
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On Quasinormality of compact perturbations of the isometries
Das, Susmita
Functional Analysis
47A55, 47B20, 47B32, 47B38, 47B91
We study the compact perturbations of an isometry on a separable Hilbert space and provide a complete characterization of when they are quasinormal. Based on that, we present a complete classification for a rank-one perturbation of a unilateral shift of finite multiplicity to be quasinormal in the setting of the Hardy space. The result can also be generalized for a separable Hilbert space. As an application, we provide a complete characterization for quasinormality of a rank-one perturbation of the Hardy shift.
title On Quasinormality of compact perturbations of the isometries
topic Functional Analysis
47A55, 47B20, 47B32, 47B38, 47B91
url https://arxiv.org/abs/2512.06967