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For $f\in \mathcal{S}$, the class of normalized functions, analytic and univalent 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 give an upper bound for the coefficient difference…

Complex Variables · Mathematics 2021-11-22 Milutin Obradovic , Derek K. Thomas , Nikola Tuneski

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 $\alpha$,…

Complex Variables · Mathematics 2019-12-30 Milutin Obradovic , 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…

Complex Variables · Mathematics 2023-10-05 Biswajit Rath , K. Sanjay Kumar , D. Vamshee Krishna

In this article, we investigate the extremal properties of logarithmic coefficients for the class $\mathcal{S}_{ch}^*$ of starlike functions associated with the hyperbolic cosine function. We establish the sharp upper bounds for the initial…

Complex Variables · Mathematics 2026-03-18 Molla Basir Ahamed , Sanju Mandal

Let $\mathcal{A}$ denote the class of analytic functions such that $f(0)=0$ and $f'(0)=1$ in the unit disk $\mathbb{D}:=\{z \in \mathbb{C}: |z|<1\}$. In this paper, we discuss the properties of a starlike subclass and compute its second and…

Complex Variables · Mathematics 2026-04-13 Vasudevarao Allu , Shobhit Kumar

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

Introducing a new method we give sharp estimates of the Hermitian Toepliz determinants of third order for the class $\mathcal{S}$ of functions univalent in the unit disc. The new approach is also illustrated on some subclasses of the class…

Complex Variables · Mathematics 2021-04-23 Milutin Obradović , Nikola Tuneski

Let $\mathcal{S}_u^*$ denote the class of all analytic functions $f$ in the unit disk $\mathbb{D}:=\{z\in\mathbb{C}:|z|<1\}$, normalized by $f(0)=f'(0)-1=0$ that satisfies the inequality $\left|zf'(z)/f(z)-1\right|<1$ in $\mathbb{D}$. In…

Complex Variables · Mathematics 2025-03-19 Md Firoz Ali , Md Nurezzaman

In the present investigation the authors obtain upper bounds for the second Hankel determinant of the classes bi-starlike and bi-convex functions of order beta.

Complex Variables · Mathematics 2015-10-08 Erhan Deniz , Murat Çağlar , Halit Orhan

We introduce a class of analytic functions subordinate to the function $1+\sinh \left( z\right) $ and obtain various necessary and sufficient conditions for functions to be in the class. These conditions mainly comprise of the coefficient…

Complex Variables · Mathematics 2020-11-11 S. Sivaprasad Kumar , Muhammad Ghaffar Khan , Bakhtiar Ahmad , Wali Khan Mashwani

In this paper, we consider polynomials orthogonal with respect to a varying perturbed Laguerre weight $e^{-n(z-\log z+t/z)}$ for $t<0$ and $z$ on certain contours in the complex plane. When the parameters $n$, $t$ and the degree $k$ are…

Classical Analysis and ODEs · Mathematics 2016-01-20 Shuai-Xia Xu , Dan Dai , Yu-Qiu Zhao

In this paper, new class of bi-univalent functions are introduced. Upper bound of the second Hankel determinant $|H_2(2)|$ of subclass of bi-univalant functions class $\Sigma$, which defined by subordination, investigated. Furthermore, some…

Complex Variables · Mathematics 2019-08-21 Alaa H. El-Qadeem , Mohamed A. Mamon

This paper examines the coefficient problems for the class of semigroup generators, a topic in complex dynamics that has recently been studied in context of geometric function theory. Further, sharp bounds of coefficient functional such as…

Complex Variables · Mathematics 2022-10-25 Surya Giri , S. Sivaprasad Kumar

In this paper, we obtain the sharp bounds of the second Hankel determinant of logarithmic inverse coefficients for the starlike and convex functions.

Complex Variables · Mathematics 2026-04-14 Vasudevarao Allu , Amal Shaji

We give an overview of known results about Hilbert matrices from the point of view of orthogonal polynomials and compute Hankel determinants of harmonic numbers and related topics.

Classical Analysis and ODEs · Mathematics 2017-05-25 Johann Cigler

Applying Johann Cigler's Hankel determinant formula in terms of the binomial coefficient determinants, which is simplified from Christian Krattenthale's, we get an explicit formula of Hankel determinants for general. As far as I know, those…

General Mathematics · Mathematics 2020-10-19 Jishe Feng

We consider the five-vertex model on a finite square lattice with fixed boundary conditions such that the configurations of the model are in a one-to-one correspondence with the boxed plane partitions (3D Young diagrams which fit into a box…

Mathematical Physics · Physics 2021-02-23 Ivan N. Burenev , Andrei G. Pronko

In the present paper, we will discuss the Hankel determinants $H(f) =a_2a_4-a_3^2$ of order 2 for normalized concave functions $f(z)=z+a_2z^2+a_3z^3+\dots$ with a pole at $p\in(0,1).$ Here, a meromorphic function is called concave if it…

Complex Variables · Mathematics 2015-12-11 Rintaro Ohno , Toshiyuki Sugawa

In this paper, we investigate the inverse logarithmic coefficients associated with the class $\mathcal{C}_e$ of analytic and univalent functions satisfying the subordination condition \[ 1+\frac{z f''(z)}{f'(z)} \prec e^z, \quad…

Complex Variables · Mathematics 2026-05-20 Pradip Das , Nabadwip Sarkar

We describe explicitly the algebra of polynomial functions on the Hilbert space of four qubit states which are invariant under the SLOCC group $SL(2,{\mathbb C})^{4}$. From this description, we obtain a closed formula for the…

Quantum Physics · Physics 2013-02-12 J. -G. Luque , J. -Y. Thibon