scholarly journals On Meromorphic Functions Defined by a New Operator Containing the Mittag–Leffler Function

Symmetry ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 210 ◽  
Author(s):  
Suhila Elhaddad ◽  
Maslina Darus
Keyword(s):  
Differential Operator ◽  
Meromorphic Function ◽  
Hypergeometric Function ◽  
Meromorphic Functions ◽  
Hadamard Product ◽  
Linear Differential Operator ◽  
Extreme Points ◽  
Growth Coefficient ◽  
Closure Theorems ◽  
Linear Differential

This study defines a new linear differential operator via the Hadamard product between a q-hypergeometric function and Mittag–Leffler function. The application of the linear differential operator generates a new subclass of meromorphic function. Additionally, the study explores various properties and features, such as convex properties, distortion, growth, coefficient inequality and radii of starlikeness. Finally, the work discusses closure theorems and extreme points.

scholarly journals Stieltjes Moment Sequences for Pattern-Avoiding Permutations

10.37236/9402 ◽  
2020 ◽  
Vol 27 (4) ◽  
Author(s):  
Alin Bostan ◽  
Andrew Elvey Price ◽  
Anthony John Guttmann ◽  
Jean-Marie Maillard
Keyword(s):  
Differential Operator ◽  
Modular Form ◽  
Density Function ◽  
Hypergeometric Function ◽  
Generating Functions ◽  
Linear Differential Operator ◽  
Moment Sequence ◽  
Growth Constant ◽  
Linear Differential ◽  
Stieltjes Moment Sequence

A small set of combinatorial sequences have coefficients that can be represented as moments of a nonnegative measure on $[0, \infty)$. Such sequences are known as Stieltjes moment sequences. They have a number of nice properties, such as log-convexity, which are useful to rigorously bound their growth constant from below. This article focuses on some classical sequences in enumerative combinatorics, denoted $Av(\mathcal{P})$, and counting permutations of $\{1, 2, \ldots, n \}$ that avoid some given pattern $\mathcal{P}$. For increasing patterns $\mathcal{P}=(12\ldots k)$, we recall that the corresponding sequences, $Av(123\ldots k)$, are Stieltjes moment sequences, and we explicitly find the underlying density function, either exactly or numerically, by using the Stieltjes inversion formula as a fundamental tool. We first illustrate our approach on two basic examples, $Av(123)$ and $Av(1342)$, whose generating functions are algebraic. We next investigate the general (transcendental) case of $Av(123\ldots k)$, which counts permutations whose longest increasing subsequences have length at most $k-1$. We show that the generating functions of the sequences $\, Av(1234)$ and $\, Av(12345)$ correspond, up to simple rational functions, to an order-one linear differential operator acting on a classical modular form given as a pullback of a Gaussian $\, _2F_1$ hypergeometric function, respectively to an order-two linear differential operator acting on the square of a classical modular form given as a pullback of a $\, _2F_1$ hypergeometric function. We demonstrate that the density function for the Stieltjes moment sequence $Av(123\ldots k)$ is closely, but non-trivially, related to the density attached to the distance traveled by a walk in the plane with $k-1$ unit steps in random directions. Finally, we study the challenging case of the $Av(1324)$ sequence and give compelling numerical evidence that this too is a Stieltjes moment sequence. Accepting this, we show how rigorous lower bounds on the growth constant of this sequence can be constructed, which are stronger than existing bounds. A further unproven assumption leads to even better bounds, which can be extrapolated to give an estimate of the (unknown) growth constant.

A subclass of meromorphic functions defined by a certain integral operator on Hilbert space

2017 ◽  
Vol 26 (2) ◽  
pp. 115-124
Author(s):  
Arzu Akgül
Keyword(s):  
Hilbert Space ◽  
Integral Operator ◽  
Meromorphic Functions ◽  
Hadamard Product ◽  
Extreme Points ◽  
Space Operator ◽  
Integral Means ◽  
New Class ◽  
Coefficient Inequality ◽  
Hilbert Space Operator

In the present paper, we introduce and investigate a new class of meromorphic functions associated with an integral operator, by using Hilbert space operator. For this class, we obtain coefficient inequality, extreme points, radius of close-to-convex, starlikeness and convexity, Hadamard product and integral means inequality.

Method of Forced Monotonicity for Conjugate type Boundary Value Problems for Ordinary Differential Equations

1988 ◽  
Vol 31 (1) ◽  
pp. 79-84
Author(s):  
P. W. Eloe ◽  
P. L. Saintignon
Keyword(s):  
Differential Operator ◽  
Differential Equations ◽  
Boundary Value Problem ◽  
Ordinary Differential Equations ◽  
Linear Differential Operator ◽  
Boundary Value ◽  
Linear Differential ◽  
Type Boundary ◽  
Sign Conditions ◽  
Conjugate Type

AbstractLet I = [a, b] ⊆ R and let L be an nth order linear differential operator defined on Cn(I). Let 2 ≦ k ≦ n and let a ≦ x1 < x2 < … < xn = b. A method of forced mono tonicity is used to construct monotone sequences that converge to solutions of the conjugate type boundary value problem (BVP) Ly = f(x, y),y(i-1) = rij where 1 ≦i ≦ mj, 1 ≦ j ≦ k, mj = n, and f : I X R → R is continuous. A comparison theorem is employed and the method requires that the Green's function of an associated BVP satisfies certain sign conditions.

Sign in / Sign up

Export Citation Format

Share Document