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Asena Çetinkaya

Publications and source records attributed to Asena Çetinkaya.

7 recordsLinked to original sources

Note on the Coefficient Conjecture of Clunie and Sheil-Small on the univalent harmonic mapping

In this article, we construct generalized harmonic univalent mappings and find its coefficients bounds. We present the counterexample to validate the coefficient conjecture proposed by Clunie and Sheil-Small for the class of functions $f=h+\overline{g}\in \mathcal{S}_{\mathcal{H}}$ with the help of these examples we improve the conjecture bounds of class $\mathcal{S}_{\mathcal{H}}$.

math.CV↗

On digamma series convertible into hypergeometric series

Series containing the digamma function arise when calculating the parametric derivatives of the hypergeometric functions and play a role in evaluation of Feynman diagrams. As these series are typically non-hypergeometric, a few instances when they are summable in terms of hypergeometric functions are of importance. In this paper, we convert multi-term identities for the generalized hypergeometric functions evaluated at unity into identities connecting them to the digamma series via the appropriate limiting process. The resulting formulas can be viewed as hypergeometric expressions for the $1$-norm of the gradient of the generalized hypergeometric function with respect to all its parameters and seem to have no direct analogues in the literature.

math.CA↗

Hypergeometric Functions at Unit Argument: Simple Derivation of Old and New Identities

The main goal of this paper is to derive a number of identities for the generalized hypergeometric function evaluated at unity and for certain terminating multivariate hypergeometric functions from the symmetries and other properties of Meijer's $G$ function. For instance, we recover two- and three-term Thomae relations for ${}_3F_2$, give two- and three-term transformations for ${}_4F_3$ with one unit shift and ${}_5F_4$ with two unit shifts in the parameters, establish multi-term identities for general ${}_{p}F_{p-1}$ and several transformations for terminating Kampé de Fériet and Srivastava $F^{(3)}$ functions. We further present a presumably new formula for analytic continuation of ${}_pF_{p-1}(1)$ in parameters and reveal somewhat unexpected connections between the generalized hypergeometric functions and the generalized and ordinary Bernoulli polynomials. Finally, we exploit some recent duality relations for the generalized hypergeometric and $q$-hypergeometric functions to derive multi-term relations for terminating series.

math.CA↗

Analytic functions with conic domains associated with certain generalized q-integral operator

In this paper, we define a new subclass of $k$-uniformly starlike functions of order $γ,\ (0\leqγ<1)$ by using certain generalized $q$-integral operator. We explore geometric interpretation of the functions in this class by connecting it with conic domains. We also investigate $q$-sufficient coefficient condition, $q$-Fekete-Szegö inequalities, $q$-Bieberbach-De Branges type coefficient estimates and radius problem for functions in this class. We conclude this paper by introducing an analogous subclass of $k$-uniformly convex functions of order $γ$ by using the generalized $q$-integral operator. We omit the results for this new class because they can be directly translated from the corresponding results of our main class.

math.CV↗

On The Coefficient Conjecture of Clunie and Sheil-Small

In this paper, we first prove relation between analytic and co-analytic part of the class harmonic univalent functions S_H(S):={f = h+\overline g|h is element of S} by means of second dilatation is constant. Next, we verify the coefficient conjecture of Clunie and Sheil-Small for class of harmonic univalent functions. Finally, we obtain distortion bounds of this class.

math.CV↗

Harmonic Univalent Functions Defined by Post Quantum Calculus Operators

We study a family of harmonic univalent functions in the open unit disc defined by using post quantum calculus operators. We first obtained a coefficient characterization of these functions. Using this, coefficients estimates, distortion and covering theorems were also obtained. The extreme points of the family and a radius result were also obtained. The results obtained include several known results as special cases.

math.CV↗