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Bohr operator on operator-valued polyanalytic functions on simply connected domains

Part of: Geometric function theory Series expansions General theory of linear operators

Published online by Cambridge University Press:  26 June 2023

Vasudevarao Allu Open the ORCID record for Vasudevarao Allu [Opens in a new window]  and
Himadri Halder
Vasudevarao Allu*
Affiliation:
School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar 752050, India
Himadri Halder
Affiliation:
Mathematics Department, Indian Institute of Technology Bombay, Mumbai 400076, India e-mail: [email protected], [email protected]
*
e-mail: [email protected]
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Abstract

In this article, we study the Bohr operator for the operator-valued subordination class $S(f)$ consisting of holomorphic functions subordinate to f in the unit disk $\mathbb {D}:=\{z \in \mathbb {C}: |z|<1\}$, where $f:\mathbb {D} \rightarrow \mathcal {B}(\mathcal {H})$ is holomorphic and $\mathcal {B}(\mathcal {H})$ is the algebra of bounded linear operators on a complex Hilbert space $\mathcal {H}$. We establish several subordination results, which can be viewed as the analogs of a couple of interesting subordination results from scalar-valued settings. We also obtain a von Neumann-type inequality for the class of analytic self-mappings of the unit disk $\mathbb {D}$ which fix the origin. Furthermore, we extensively study Bohr inequalities for operator-valued polyanalytic functions in certain proper simply connected domains in $\mathbb {C}$. We obtain Bohr radius for the operator-valued polyanalytic functions of the form $F(z)= \sum _{l=0}^{p-1} \overline {z}^l \, f_{l}(z) $, where $f_{0}$ is subordinate to an operator-valued convex biholomorphic function, and operator-valued starlike biholomorphic function in the unit disk $\mathbb {D}$.

Keywords

Banach algebravon Neumann inequalitypolyanalytic functionsBohr operatorsimply connected domains

MSC classification

Primary: 47A56: Functions whose values are linear operators (operator and matrix valued functions, etc., including analytic and meromorphic ones) 30B10: Power series (including lacunary series) 47A63: Operator inequalities
Secondary: 30C45: Special classes of univalent and multivalent functions (starlike, convex, bounded rotation, etc.)
Type
Article
Information
Canadian Mathematical Bulletin , Volume 66 , Issue 4 , December 2023 , pp. 1411 - 1422
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Copyright
© The Author(s), 2023. Published by Cambridge University Press on behalf of The Canadian Mathematical Society

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Footnotes

The first-named author is supported by SERB-CRG, and the second-named author is supported by the Institute Postdoctoral Fellowship of IIT Bombay, India.

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