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In this paper we give improved, probably not sharp, upper bounds of the Hankel determinant of third order for various classes of univalent functions and conjecture the sharp one.

复变函数 · 数学 2020-10-09 Milutin Obradovic , Nikola Tuneski

In this paper we improve the upper bound of the third order Hankel determinant for the class of Ozaki close-to-convex functions. The sharp bound is conjectured.

复变函数 · 数学 2020-10-28 Milutin Obradović , Nikola Tuneski

In this paper, we obtain sharp bounds for the third Hankel determinants of the coefficients of the inverse of bounded turning functions. Thus answering a negatively to a conjecture recently posed regarding these functions. Additionally, we…

复变函数 · 数学 2025-06-23 Mohsan Raza , Nikola Tuneski

The objective of this paper is to find the best possible upper bound of the third Hankel determinant for the inverse of convex functions.

复变函数 · 数学 2023-01-06 Biswajit Rath , K. Sanjay Kumar , D. Vamshee Krishna

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.

复变函数 · 数学 2024-11-20 Milutin Obradović , Nikola Tuneski

Focus in this paper is on the Hankel determinant, $H_3(1)$, for the well-known classes of bounded-turning, starlike and convex functions in the open unit disk $E=\{z\in \mathbb{C}\colon|z|<1\}$. The results obtained complete the series of…

复变函数 · 数学 2009-10-21 K. O. Babalola

Let ${\mathcal A}$ be the class of functions that are analytic in the unit disc ${\mathbb D}$, normalized such that $f(z)=z+\sum_{n=2}^\infty a_nz^n$, and let class ${\mathcal U}(\lambda)$, $0<\lambda\le1$, consists of functions…

复变函数 · 数学 2021-11-22 Milutin Obradović , Nikola Tuneski

Let $f$ be analytic in the unit disk $\mathbb{D}= \{z \in \mathbb{C}~:~ |z| < 1\}$, and $\mathcal{S}$ be the subclass of normalized univalent functions given by $f(z)=\sum_{n=1}^{\infty}a_{n}z^{n},~a_{1}:=1$ for $z \in\mathbb{D}$. We…

复变函数 · 数学 2023-10-05 Biswajit Rath , K. Sanjay Kumar , D. Vamshee Krishna

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.

复变函数 · 数学 2019-12-16 Milutin Obradović , Nikola Tuneski

For $f\in \mathcal{S}$, the class univalent functions in the unit disk $\mathbb{D}$ and given by $f(z)=z+\sum_{n=2}^{\infty} a_n z^n$ for $z\in \mathbb{D}$, we improve previous bounds for the second and third Hankel determinants in case…

复变函数 · 数学 2024-11-21 Milutin Obradović , Nikola Tuneski

In this paper, we obtain the upper bounds to the third Hankel determinants for starlike functions of order $\alpha$, convex functions of order $\alpha$ and bounded turning functions of order $\alpha$. Furthermore, several relevant results…

复变函数 · 数学 2017-03-29 Yong Sun , Zhi-Gang Wang , Antti Rasila

In this paper we determine the upper bounds of $|H_{2}(3)|$ for the inverse functions of functions of some classes of univalent functions, where $H_{2}(3)(f)=a_{3}a_{5}-a_{4}^{2}$ is the Hankel determinant of a special type.

复变函数 · 数学 2022-11-23 Milutin Obradović , Nikola Tuneski

In this paper, we provide an estimation for the sharp bound of the third Hankel determinant of starlike functions of order $\alpha$, where $\alpha$ ranges in the interval $[0, 1/6]\cup \{1/2\}$ and thereby extending the result of Rath et…

复变函数 · 数学 2023-09-07 Neha Verma , S. Sivaprasad Kumar

The sharp bound for the third Hankel determinant for the coefficients of the inverse function of starlike function of order $1/2$ is obtained. In light of this, we can deduce that the functionals $|H_3(1)(f)|$ and $|H_3(1)(f^{-1})|$ exhibit…

复变函数 · 数学 2023-07-07 Molla Basir Ahamed , Partha Pratim Roy

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.

复变函数 · 数学 2015-10-26 H. Orhan , N. Magesh , J. Yamini

This paper deals with sharp bounds for the third-order Hankel, Toeplitz and Hermitian-Toeplitz determinant of functions belonging to the class $\mathcal{S}^*_{B}$ of starlike functions associated with a balloon-shaped domain, given by \[…

复变函数 · 数学 2026-03-12 S. Sivaprasad Kumar , Arya Tripathi

The aim of this paper is to obtain an upper bound to the second Hankel the determinant for starlike and convex functions of order.

复变函数 · 数学 2019-03-28 A. A. Amourah , Anas Aljarah , M. Darus

We prove a conjecture concerning the third Hankel determinant, proposed in ``Anal. Math. Phys., https://doi.org/10.1007/s13324-021-00483-7", which states that $|H_3(1)|\leq 1/9$ is sharp for the class $\mathcal{S}_{\wp}^{*}=\{zf'(z)/f(z)…

复变函数 · 数学 2022-08-08 Neha Verma , S. Sivaprasad Kumar

Let $f$ be analytic in the unit disk $\mathbb D$ and normalized so that $f(z)=z+a_2z^2+a_3z^3+\cdots$. In this paper, we give upper bounds of the Hankel determinant of second order for the classes of starlike functions of order $\alpha$,…

复变函数 · 数学 2019-12-30 Milutin Obradovic , Nikola Tuneski

Let $f$ be analutic in the unit disk $\mathbb D$ and normalized so that $f(z)=z+a_2z^2+a_3z^3+\cdots$. In this paper we give sharp bound of Hankel determinant of the second order for the class of analytic unctions satisfying \[ \left|\arg…

复变函数 · 数学 2019-03-20 Milutin Obradovic , Nikola Tuneski
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