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Bibliographic Details
Main Authors: Kubrusly, C. S., Stankovic, H. M
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2601.07203
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author Kubrusly, C. S.
Stankovic, H. M
author_facet Kubrusly, C. S.
Stankovic, H. M
contents The paper extends three results regarding the nth root problem by embedding classes of Hilbert-space operators into the class of posinormal operators. For instance, it is shown that (i) for coposinormal operators, if T is paranormal and T^n is quasinormal, then T is normal, and (ii) for posinormal operators, if T is k-quasiparanormal and T^n is normal, then T is normal. Moreover, (iii) it is also shown that the latter result is not conditioned to the separability of the underlying Hilbert space, even if T is not posinormal, where, in such a case, T is the direct sum of a normal operator with a nilpotent one.
format Preprint
id arxiv_https___arxiv_org_abs_2601_07203
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Posinormality and the Root Problem
Kubrusly, C. S.
Stankovic, H. M
Functional Analysis
47B15, 47B20
The paper extends three results regarding the nth root problem by embedding classes of Hilbert-space operators into the class of posinormal operators. For instance, it is shown that (i) for coposinormal operators, if T is paranormal and T^n is quasinormal, then T is normal, and (ii) for posinormal operators, if T is k-quasiparanormal and T^n is normal, then T is normal. Moreover, (iii) it is also shown that the latter result is not conditioned to the separability of the underlying Hilbert space, even if T is not posinormal, where, in such a case, T is the direct sum of a normal operator with a nilpotent one.
title Posinormality and the Root Problem
topic Functional Analysis
47B15, 47B20
url https://arxiv.org/abs/2601.07203