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Using some properties of the Grunsky coefficients we improve earlier results for upper bounds of the Hankel determinants of the second and third order for the class $\mathcal{S}$ of univalent functions.

Complex Variables · Mathematics 2024-11-20 Milutin Obradović , Nikola Tuneski

Let function $f$ be normalized, analytic and univalent in the unit disk ${\mathbb D}=\{z:|z|<1\}$ and $f(z)=z+\sum_{n=2}^{\infty} a_n z^n$. Using a method based on Grusky coefficients we study several problems over that class of univalent…

Complex Variables · Mathematics 2025-05-29 Milutin Obradović , Nikola Tuneski

In this paper a survey is given of application of a method based on Grunsky coefficients for obtaining different estimates (some sharp) for the general class of univalent functions where no analytical characterisation exists. More…

Complex Variables · Mathematics 2025-10-29 M. Obradovic , N. Tuneski

Let $\mathcal{S}$ denote the class of functions $f$ which are analytic and univalent in the unit disk ${\mathbb D}=\{z:|z|<1\}$ and normalized with $f(z)=z+\sum_{n=2}^{\infty} a_n z^n$. Using a method based on Grusky coefficients we study…

Complex Variables · Mathematics 2022-01-20 Milutin Obradović , Nikola Tuneski

In this paper, we consider a general subclass of analytic and bi-univalent functions in the open unit disk in the complex plane. Making use of the Chebyshev polynomials, we obtain upper bound estimate for the second Hankel determinant for…

Complex Variables · Mathematics 2017-02-23 Nizami Mustafa

In this paper we consider some properties of the initial logarithmic coefficients for inverse functions of functions univalent in the unit disc. The case of convex functions is treated separately. We give estimate, in some cases sharp, of…

Complex Variables · Mathematics 2026-05-15 Milutin Obradović , Nikola Tuneski , Paweł Zaprawa

We consider a family of all analytic and univalent functions in the unit disk of the form $f(z)=z+a_2z^2+a_3z^3+\cdots$. The aim of this article is to investigate the bounds of the difference of moduli of initial successive coefficients,…

Complex Variables · Mathematics 2021-07-30 Vibhuti Arora

In this paper, we investigate the sharp bounds of the second Hankel determinant of Logarithmic coefficients for the starlike and convex functions with respect to symmetric points in the open unit disk.

Complex Variables · Mathematics 2021-12-07 Vasudeavarao Allu , Vibhuti Arora , Amal Shaji

Making use of Chebyshev polynomials, we obtain upper bound estimate for the second Hankel determinant of a subclass $\mathcal{N}_{\sigma }^{\mu}\left( \lambda ,t\right) $ of bi-univalent function class $\sigma.$

Complex Variables · Mathematics 2017-11-21 H. Orhan , N. Magesh , V. K. Balaji

In the present work, we propose to investigate the second Hankel determinant inequalities for certain class of analytic and bi-univalent functions. Some interesting applications of the results presented here are also discussed.

Complex Variables · Mathematics 2015-10-26 H. Orhan , N. Magesh , J. Yamini

In this paper we give the upper bounds of the Hankel determinants of the second and third order for the class $\mathcal{S}$ of univalent functions in the unit disc.

Complex Variables · Mathematics 2019-12-16 Milutin Obradović , Nikola Tuneski

A bi-univalent function is a univalent function defined on the unit disk with its inverse also univalent on the unit disk. Estimates for the initial coefficients are obtained for bi-univalent functions belonging to certain classes defined…

Complex Variables · Mathematics 2013-03-01 S. Sivaprasad Kumar , Virendra Kumar , V. Ravichandran

In this paper we give simple proofs for the bounds (some of them sharp) of the difference of the moduli of the second and the first logarithmic coefficient for the general class of univalent functions and for the class of convex univalent…

Complex Variables · Mathematics 2023-11-28 Milutin Obradovic , Nikola Tuneski

Our objective in this paper is to introduce and investigate comprehensive-constructed subclasses of normalized analytic and bi-univalent functions on the unit open disc. Bounds for the second and third Tayler-Maclaurin coefficients of…

Complex Variables · Mathematics 2022-02-24 S. A. Saleh , Alaa H. El-Qadeem , Mohamed A. Mamon

In this sequel to the recent work (see Azizi et al., 2015), we investigate a subclass of analytic and bi-univalent functions in the open unit disk. We obtain bounds for initial coefficients, the Fekete-Szeg\"o inequality and the second…

Complex Variables · Mathematics 2015-09-18 N. Magesh , J. Yamini

Making use of the Hankel determinant and the Ruscheweyh derivative, in this work, we consider a general subclass of m-fold symmetric normalized bi-univalent functions defined in the open unit disk. Moreover, we investigate the bounds for…

We consider a family of all analytic and univalent functions (i.e., one-to-one) in the unit disk $\mathbb{D}:=\{z\in \mathbb{C}:|z|<1\}$ of the form $f(z)=z+a_2z^2+a_3z^3+\cdots$. In this paper, we obtain the sharp bounds of the second…

Complex Variables · Mathematics 2021-12-09 Vasudevarao Allu , Vibhuti Arora

In this paper, we give sharp bounds of the difference of the moduli of the second and the first logarithmic coefficient for the functions on the class $\mathcal U$, for the $\alpha$-convex functions, and for the class $\mathcal{G}(\alpha)$…

Complex Variables · Mathematics 2024-04-03 Milutin Obradović , Nikola Tuneski

We establish that the Grunsky norm of any normalized univalent function on the disk is completely determined by the squares of holomorphic abelian differentials (in contrast to the Teichmuller norm, which relates to all integrable…

Complex Variables · Mathematics 2023-05-05 Samuel L. Krushkal

This article presents some interesting and novel results concerning the average modulus of random polynomials on the unit circle and the unit disc, with coefficients distributed as standard normal variates. The paper also introduces new…

Complex Variables · Mathematics 2026-05-19 Sajad A. Sheikh , Mohd. Ibrahim Mir
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