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Applications of the Schwarz Lemma related to Boundary Points

Journal of the Korean Society of Mathematical Education Series B: The Pure and Applied Mathematics / Journal of the Korean Society of Mathematical Education Series B: The Pure and Applied Mathematics, (P)1226-0657; (E)2287-6081
2023, v.30 no.3, pp.337-345
https://doi.org/https://doi.org/10.7468/jksmeb.2023.30.3.337
Bulent Nafi Ornek
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Abstract

Different versions of the boundary Schwarz lemma for the &#x1D4A9; (&#x1D70C;) class are discussed in this study. Also, for the function g(z) = z+b<sub>2</sub>z<sup>2</sup>+b<sub>3</sub>z<sup>3</sup>+... defined in the unit disc D such that g &#x2208; &#x1D4A9; (&#x1D70C;), we estimate a modulus of the angular derivative of g(z) function at the boundary point 1 &#x2208; &#x1D715;D with g'(1) = 1 + &#x1D70E; (1 - &#x1D70C;), where <TEX>${\rho}={\frac{1}{n}}{\sum\limits_{i=1}^{n}}g(c_i)={\frac{g^{\prime}(c_1)+g^{\prime}(c_2)+{\ldots}+g^{\prime}(c_n)}{n}}{\in}g^{\prime}(D)$</TEX> and &#x1D70C;&#x2260;1, &#x1D70E; > 1 and c<sub>1</sub>, c<sub>2</sub>, ..., c<sub>n</sub> &#x2208; &#x1D715;D. That is, we shall give an estimate below |g"(1)| according to the first nonzero Taylor coefficient of about two zeros, namely z = 0 and z &#x2260; 0. Estimating is made by using the arithmetic average of n different derivatives g'(c<sub>1</sub>), g'(c<sub>2</sub>), ..., g'(c<sub>n</sub>).

keywords
Julia-Wolff lemma, analytic function, Schwarz lemma, angular derivative

Journal of the Korean Society of Mathematical Education Series B: The Pure and Applied Mathematics