Composition operators on some semi-Hilbert spaces

Fuente: arXiv
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Autores principales: Estaremi, Y., Ghafri, M. S. Al
Formato: Preprint
Publicado: 2025
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author Estaremi, Y.
Ghafri, M. S. Al
author_facet Estaremi, Y.
Ghafri, M. S. Al
contents This paper investigates composition operators and weighted composition operators on semi-Hilbert spaces induced by positive multiplication operators on \( L^2(μ) \). Within the framework of \( A \)-adjoint operators, we characterize conditions under which a composition operator \( C_φ\) is \( A \)-selfadjoint, \( A \)-normal, \( A \)-quasinormal, or \( A \)-unitary, where \( A = M_u \) denotes a positive multiplication operator. Additionally, we provide necessary and sufficient conditions for \( C_φ\) to be an \( A \)-isometry or an \( A \)-partial isometry. Analogous results are also obtained when \( A \) is a positive composition operator. Several examples are presented to illustrate the applicability of the main results.
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publishDate 2025
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spellingShingle Composition operators on some semi-Hilbert spaces
Estaremi, Y.
Ghafri, M. S. Al
Functional Analysis
This paper investigates composition operators and weighted composition operators on semi-Hilbert spaces induced by positive multiplication operators on \( L^2(μ) \). Within the framework of \( A \)-adjoint operators, we characterize conditions under which a composition operator \( C_φ\) is \( A \)-selfadjoint, \( A \)-normal, \( A \)-quasinormal, or \( A \)-unitary, where \( A = M_u \) denotes a positive multiplication operator. Additionally, we provide necessary and sufficient conditions for \( C_φ\) to be an \( A \)-isometry or an \( A \)-partial isometry. Analogous results are also obtained when \( A \) is a positive composition operator. Several examples are presented to illustrate the applicability of the main results.
title Composition operators on some semi-Hilbert spaces
topic Functional Analysis
url https://arxiv.org/abs/2508.05042