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arXiv 2009.08683math.CV
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某些调和映射的Bohr不等式

The Bohr inequality for certain harmonic mappings

School of Basic Science, Indian Institute of Technology Bhubaneswar(印度技术学院布巴内斯瓦尔基础科学学院)

Vasudevarao Allu, Himadri Halder

AI总结:

本文研究了特定调和映射类HC(ϕ)和HC_c(ϕ)的Bohr不等式,通过子ordination类的Bohr现象,确定了半径R_f,使得不等式在单位盘内成立,并推导出相关结论。

摘要:

令ϕ为在单位盘D={z∈C:|z|<1}内解析且单射(即一一对应)的函数,使得ϕ(D)具有正实部,关于实轴对称,以ϕ(0)=1为星型,且ϕ′(0)>0。若f∈C(ϕ)当且仅当1+zf''(z)/f'(z)≺ϕ(z),且f∈C_c(ϕ)当且仅当2(zf'(z))'/(f(z)+\overline{f(\bar{z})})'≺ϕ(z)对z∈D成立。本文考虑由调和映射f=h+\overline{g}组成的类HC(ϕ)和HC_c(ϕ),其中h和g分别属于C(ϕ)和C_c(ϕ),且g'(z)=αz h'(z)且|α|<1。利用子ordination类的Bohr现象[引理1],我们找到半径R_f<1,使得Bohr不等式|z|+Σ_{n=2}^∞(|a_n|+|b_n|)|z|^n ≤d(f(0),∂f(D))在|z|=r≤R_f时成立。作为这些结果的推论,我们得到了关于上述类别的Bohr不等式的几个有趣结论。

英文摘要:

Let $ϕ$ be analytic and univalent ({\it i.e.,} one-to-one) in $\mathbb{D}:=\{z\in\mathbb{C}: |z|<1\}$ such that $ϕ(\mathbb{D})$ has positive real part, is symmetric with respect to the real axis, starlike with respect to $ϕ(0)=1,$ and $ϕ' (0)>0$. A function $f \in \mathcal{C}(ϕ)$ if $1+ zf''(z)/f'(z) \prec ϕ(z),$ and $f\in \mathcal{C}_{c}(ϕ)$ if $2(zf'(z))'/(f(z)+\overline{f(\bar{z})})' \prec ϕ(z)$ for $ z\in \mathbb{D}$. In this article, we consider the classes $\mathcal{HC}(ϕ)$ and $\mathcal{HC}_{c}(ϕ)$ consisting of harmonic mappings $f=h+\overline{g}$ of the form $$ h(z)=z+ \sum \limits_{n=2}^{\infty} a_{n}z^{n} \quad \mbox{and} \quad g(z)=\sum \limits_{n=2}^{\infty} b_{n}z^{n} $$ in the unit disk $\mathbb{D}$, where $h$ belongs to $\mathcal{C}(ϕ)$ and $\mathcal{C}_{c}(ϕ)$ respectively, with the dilation $g'(z)=αz h'(z)$ and $|α|<1$. Using the Bohr phenomenon for subordination classes \cite[Lemma 1]{bhowmik-2018}, we find the radius $R_{f}<1$ such that Bohr inequality $$ |z|+\sum_{n=2}^{\infty} (|a_{n}|+|b_{n}|)|z|^{n} \leq d(f(0),\partial f(\mathbb{D})) $$ holds for $|z|=r\leq R_{f}$ for the classes $\mathcal{HC}(ϕ)$ and $\mathcal{HC}_{c}(ϕ)$ . As a consequence of these results, we obtain several interesting corollaries on Bohr inequality for the aforesaid classes.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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