• Bulletin of the Korean Mathematical Society
• /
• v.50 no.5
• /
• pp.1531-1538
• /
• 2013

In the present investigation, the author introduces two interesting subclasses of normalized meromorphic univalent functions $w=f(z)$ defined on $\tilde{\Delta}:=\{z{\in}\mathbb{C}:1<{\mid}z{\mid}<{\infty}\}$ whose inverse $f^{-1}(w)$ is also univalent meromorphic in $\tilde{\Delta}$. Estimates for the initial coefficients are obtained for the functions in these new subclasses.

• Communications of the Korean Mathematical Society
• /
• v.33 no.4
• /
• pp.1229-1237
• /
• 2018

In this paper, we obtain the coefficient bounds for subclass of meromorphic bi-univalent functions by using the Faber polynomial expansions. The results presented in this paper would generalize and improve some recent works.

• Communications of the Korean Mathematical Society
• /
• v.32 no.2
• /
• pp.389-397
• /
• 2017

In this paper, we introduce and investigate an interesting subclass of meromorphic bi-univalent functions defined on ${\Delta}=\{z{\in}{\mathbb{C}}$ : 1 < |z| < ${\infty}\}$. For functions belonging to this class, estimates on the initial coefficients are obtained. The results presented in this paper would generalize and improve some recent works of several earlier authors.

• Bulletin of the Korean Mathematical Society
• /
• v.55 no.3
• /
• pp.999-1006
• /
• 2018

In this article we consider the class ${\mathcal{A}}(p)$ which consists of functions that are meromorphic in the unit disc $\mathbb{D}$ having a simple pole at $z=p{\in}(0,1)$ with the normalization $f(0)=0=f^{\prime}(0)-1$. First we prove some sufficient conditions for univalence of such functions in $\mathbb{D}$. One of these conditions enable us to consider the class ${\mathcal{A}}_p({\lambda})$ that consists of functions satisfying certain differential inequality which forces univalence of such functions. Next we establish that ${\mathcal{U}}_p({\lambda}){\subsetneq}{\mathcal{A}}_p({\lambda})$, where ${\mathcal{U}}_p({\lambda})$ was introduced and studied in [2]. Finally, we discuss some coefficient problems for ${\mathcal{A}}_p({\lambda})$ and end the article with a coefficient conjecture.

• Kyungpook Mathematical Journal
• /
• v.48 no.3
• /
• pp.379-385
• /
• 2008

Making use of a linear operator, we introduce certain subclass of meromorphically univalent functions in the punctured unit disk and study its properties including some inclusion results, coefficient and distortion problems. Our result generalize many results known in the literature.

• Bulletin of the Korean Mathematical Society
• /
• v.37 no.2
• /
• pp.291-301
• /
• 2000

We give sufficient coefficient conditions for a class of meromorphic univalent harmonic functions that are starlike of some order. Furthermore, it is shown that these conditions are also necessary when the coefficients of the analytic part of the function are positive and the coefficients of the co-analytic part of the function are negative. Extreme points, convolution and convex combination conditions for these classes are also determined. Fianlly, comparable results are given for the convex analogue.

• Journal of applied mathematics & informatics
• /
• v.41 no.5
• /
• pp.907-921
• /
• 2023

In this article, we are presenting and examining a subclass of Meromorphic univalent functions as stated by the Bessel function. We get disparities in terms of coefficients, properties of distortion, closure theorems, Hadamard product. Finally, for the class Σ^*(℘, ℓ, ℏ, τ, c), we obtain integral transformations.

• East Asian mathematical journal
• /
• v.27 no.3
• /
• pp.299-308
• /
• 2011

The purpose of the present paper is to obtain some subordination and superordination preserving properties involving a certain family of multiplier transformations for meromorphic functions in the open unit disk. The sandwich-type theorems for these linear operators are also considered.

• Communications of the Korean Mathematical Society
• /
• v.6 no.2
• /
• pp.225-231
• /
• 1991

• Kyungpook Mathematical Journal
• /
• v.29 no.2
• /
• pp.133-139
• /
• 1989

A generalization class $\sum_{P}$(${\alpha}$, ${\beta}$, ${\gamma}$) of certain meromorphic univalent functions with positive coefficients is introduced. The class $\sum_{P}$(${\alpha}$, ${\beta}$, ${\gamma}$) is a generalization of the class which was stuied by N.E. Cho, S.H. Lee and S. Qwa [1]. The object of the present paper is to prove some properties of functions in the class $\sum_{P}$(${\alpha}$, ${\beta}$, ${\gamma}$).