{"title":"On Bohr's inequality for special subclasses of stable starlike harmonic mappings","authors":"Wei Jin, Zhihong Liu, Qian Hu, Wenbo Zhang","doi":"10.1515/math-2023-0141","DOIUrl":null,"url":null,"abstract":"The focus of this article is to explore the Bohr inequality for a specific subset of harmonic starlike mappings introduced by Ghosh and Vasudevarao (<jats:italic>Some basic properties of certain subclass of harmonic univalent functions</jats:italic>, Complex Var. Elliptic Equ. 63 (2018), no. 12, 1687–1703.). This set is denoted as <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_math-2023-0141_eq_001.png\" /> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\"> <m:msubsup> <m:mrow> <m:mi mathvariant=\"script\">ℬ</m:mi> </m:mrow> <m:mrow> <m:mi>H</m:mi> </m:mrow> <m:mrow> <m:mn>0</m:mn> </m:mrow> </m:msubsup> <m:mrow> <m:mo>(</m:mo> <m:mrow> <m:mi>M</m:mi> </m:mrow> <m:mo>)</m:mo> </m:mrow> <m:mo>≔</m:mo> <m:mrow> <m:mo stretchy=\"false\">{</m:mo> <m:mrow> <m:mi>f</m:mi> <m:mo>=</m:mo> <m:mi>h</m:mi> <m:mo>+</m:mo> <m:mover accent=\"true\"> <m:mrow> <m:mi>g</m:mi> </m:mrow> <m:mrow> <m:mo stretchy=\"true\">¯</m:mo> </m:mrow> </m:mover> <m:mo>∈</m:mo> <m:msub> <m:mrow> <m:mi mathvariant=\"script\">ℋ</m:mi> </m:mrow> <m:mrow> <m:mn>0</m:mn> </m:mrow> </m:msub> <m:mo>:</m:mo> <m:mrow> <m:mo stretchy=\"false\">∣</m:mo> <m:mrow> <m:mi>z</m:mi> <m:msup> <m:mrow> <m:mi>h</m:mi> </m:mrow> <m:mrow> <m:mo accent=\"true\">″</m:mo> </m:mrow> </m:msup> <m:mrow> <m:mo>(</m:mo> <m:mrow> <m:mi>z</m:mi> </m:mrow> <m:mo>)</m:mo> </m:mrow> </m:mrow> <m:mo stretchy=\"false\">∣</m:mo> </m:mrow> <m:mo>≤</m:mo> <m:mi>M</m:mi> <m:mo>−</m:mo> <m:mrow> <m:mo stretchy=\"false\">∣</m:mo> <m:mrow> <m:mi>z</m:mi> <m:msup> <m:mrow> <m:mi>g</m:mi> </m:mrow> <m:mrow> <m:mo accent=\"true\">″</m:mo> </m:mrow> </m:msup> <m:mrow> <m:mo>(</m:mo> <m:mrow> <m:mi>z</m:mi> </m:mrow> <m:mo>)</m:mo> </m:mrow> </m:mrow> <m:mo stretchy=\"false\">∣</m:mo> </m:mrow> </m:mrow> <m:mo stretchy=\"false\">}</m:mo> </m:mrow> </m:math> <jats:tex-math>{{\\mathcal{ {\\mathcal B} }}}_{H}^{0}\\left(M):= \\{f=h+\\overline{g}\\in {{\\mathcal{ {\\mathcal H} }}}_{0}:| z{h}^{^{\\prime\\prime} }\\left(z)| \\le M-| z{g}^{^{\\prime\\prime} }\\left(z)| \\}</jats:tex-math> </jats:alternatives> </jats:inline-formula> for <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_math-2023-0141_eq_002.png\" /> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\"> <m:mi>z</m:mi> <m:mo>∈</m:mo> <m:mi mathvariant=\"double-struck\">D</m:mi> </m:math> <jats:tex-math>z\\in {\\mathbb{D}}</jats:tex-math> </jats:alternatives> </jats:inline-formula>, where <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_math-2023-0141_eq_003.png\" /> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\"> <m:mn>0</m:mn> <m:mo><</m:mo> <m:mi>M</m:mi> <m:mo>≤</m:mo> <m:mn>1</m:mn> </m:math> <jats:tex-math>0\\lt M\\le 1</jats:tex-math> </jats:alternatives> </jats:inline-formula>. It is worth mentioning that the functions belonging to the class <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_math-2023-0141_eq_004.png\" /> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\"> <m:msubsup> <m:mrow> <m:mi mathvariant=\"script\">ℬ</m:mi> </m:mrow> <m:mrow> <m:mi>H</m:mi> </m:mrow> <m:mrow> <m:mn>0</m:mn> </m:mrow> </m:msubsup> <m:mrow> <m:mo>(</m:mo> <m:mrow> <m:mi>M</m:mi> </m:mrow> <m:mo>)</m:mo> </m:mrow> </m:math> <jats:tex-math>{{\\mathcal{ {\\mathcal B} }}}_{H}^{0}\\left(M)</jats:tex-math> </jats:alternatives> </jats:inline-formula> are recognized for their stability as starlike harmonic mappings. With this in mind, this research has a twofold goal: first, to determine the optimal Bohr radius for this specific subclass of harmonic mappings, and second, to extend the Bohr-Rogosinski phenomenon to the same subclass.","PeriodicalId":48713,"journal":{"name":"Open Mathematics","volume":"731 1","pages":""},"PeriodicalIF":1.0000,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Open Mathematics","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.1515/math-2023-0141","RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
The focus of this article is to explore the Bohr inequality for a specific subset of harmonic starlike mappings introduced by Ghosh and Vasudevarao (Some basic properties of certain subclass of harmonic univalent functions, Complex Var. Elliptic Equ. 63 (2018), no. 12, 1687–1703.). This set is denoted as ℬH0(M)≔{f=h+g¯∈ℋ0:∣zh″(z)∣≤M−∣zg″(z)∣}{{\mathcal{ {\mathcal B} }}}_{H}^{0}\left(M):= \{f=h+\overline{g}\in {{\mathcal{ {\mathcal H} }}}_{0}:| z{h}^{^{\prime\prime} }\left(z)| \le M-| z{g}^{^{\prime\prime} }\left(z)| \} for z∈Dz\in {\mathbb{D}}, where 0<M≤10\lt M\le 1. It is worth mentioning that the functions belonging to the class ℬH0(M){{\mathcal{ {\mathcal B} }}}_{H}^{0}\left(M) are recognized for their stability as starlike harmonic mappings. With this in mind, this research has a twofold goal: first, to determine the optimal Bohr radius for this specific subclass of harmonic mappings, and second, to extend the Bohr-Rogosinski phenomenon to the same subclass.
期刊介绍:
Open Mathematics - formerly Central European Journal of Mathematics
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