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Starlike functions of complex order involving q-hypergeometric functions with fixed point

Kaliappan Vijaya, Gangadharan Murugusundaramoorthy, Murugesan Kasthuri (2014)

Annales Universitatis Paedagogicae Cracoviensis. Studia Mathematica

Recently Kanas and Ronning introduced the classes of starlike and convex functions, which are normalized with ƒ(ξ) = ƒ0(ξ) − 1 = 0, ξ (|ξ| = d) is a fixed point in the open disc U = {z ∈ ℂ: |z| < 1}. In this paper we define a new subclass of starlike functions of complex order based on q-hypergeometric functions and continue to obtain coefficient estimates, extreme points, inclusion properties and neighbourhood results for the function class T Sξ(α, β,γ). Further, we obtain integral means inequalities...

Starlikeness of functions satisfying a differential inequality

Rosihan M. Ali, S. Ponnusamy, Vikramaditya Singh (1995)

Annales Polonici Mathematici

In a recent paper Fournier and Ruscheweyh established a theorem related to a certain functional. We extend their result differently, and then use it to obtain a precise upper bound on α so that for f analytic in |z| < 1, f(0) = f'(0) - 1 = 0 and satisfying Re{zf''(z)} > -λ, the function f is starlike.

Starlikeness of polynomials and finite Blaschke products

Alan Gluchoff, Frederick Hartmann (2008)

Annales Polonici Mathematici

The radius of starlikeness for polynomial mappings and finite Blaschke products with zeroes distributed at equal angles around a circle centered at the origin, as well as with zeroes concentrated at a single point, are considered, and sharp bounds are obtained. Results expressing the radius of starlikeness of an arbitrary polynomial or Blaschke product in terms of the magnitudes of the zeroes are also given. These are also sharp.

Stević-Sharma type operators on Fock spaces in several variables

Lijun Ma, Zicong Yang (2024)

Czechoslovak Mathematical Journal

Let ϕ be an entire self-map of ℂ N , u 0 be an entire function on ℂ N and 𝐮 = ( u 1 , ⋯ , u N ) be a vector-valued entire function on ℂ N . We extend the Stević-Sharma type operator to the classcial Fock spaces, by defining an operator T u 0 , 𝐮 , ϕ as follows: - . 4 p t T u 0 , 𝐮 , ϕ f = u 0 · f ∘ ϕ + ∑ i = 1 N u i · ∂ f ∂ z i ∘ ϕ . We investigate the boundedness and compactness of T u 0 , 𝐮 , ϕ on Fock spaces. The complex symmetry and self-adjointness of T u 0 , 𝐮 , ϕ are also characterized.

Stieltjes moment problem in general Gelfand-Shilov spaces

Alberto Lastra, Javier Sanz (2009)

Studia Mathematica

The Stieltjes moment problem is studied in the framework of general Gelfand-Shilov spaces, subspaces of the space of rapidly decreasing smooth complex functions, which are defined by imposing suitable bounds on their elements in terms of a given sequence M. Necessary and sufficient conditions on M are stated for the problem to have a solution, sometimes coming with linear continuous right inverses of the moment map, sending a function to the sequence of its moments. On the way, some results on the...

Stochastic continuity and approximation

Leon Brown, Bertram Schreiber (1996)

Studia Mathematica

This work is concerned with the study of stochastic processes which are continuous in probability, over various parameter spaces, from the point of view of approximation and extension. A stochastic version of the classical theorem of Mergelyan on polynomial approximation is shown to be valid for subsets of the plane whose boundaries are sets of rational approximation. In a similar vein, one can obtain a version in the context of continuity in probability of the theorem of Arakelyan on the uniform...

Stone-Weierstrass theorem

Guy Laville, Ivan Ramadanoff (1996)

Banach Center Publications

It will be shown that the Stone-Weierstrass theorem for Clifford-valued functions is true for the case of even dimension. It remains valid for the odd dimension if we add a stability condition by principal automorphism.

Strengthened Moser’s conjecture, geometry of Grunsky coefficients and Fredholm eigenvalues

Samuel Krushkal (2007)

Open Mathematics

The Grunsky and Teichmüller norms ϰ(f) and k(f) of a holomorphic univalent function f in a finitely connected domain D ∋ ∞ with quasiconformal extension to ℂ ^ are related by ϰ(f) ≤ k(f). In 1985, Jürgen Moser conjectured that any univalent function in the disk Δ* = z: |z| > 1 can be approximated locally uniformly by functions with ϰ(f) < k(f). This conjecture has been recently proved by R. Kühnau and the author. In this paper, we prove that approximation is possible in a stronger sense, namely,...

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