T. Sugawa

activity

20072026

most citedCoefficient estimates of analytic endomorphisms of the unit disk fixing a point with applications to concave functions

15 citations · 52 across the 47 of their papers we have counts for

collaborators

Showing 2017Show all

5 papers · 1 filter

math.CV2017

On the hyperbolic distance of $n$ -times punctured spheres

Toshiyuki Sugawa, Matti Vuorinen, Tanran Zhang

The length of the shortest closed geodesic in a hyperbolic surface $X$ is called the systole of $X .$ When $X$ is an $n$ -times punctured sphere $C^∖ A$ where…

math.CV2017

Construction of nearly hyperbolic distance on punctured spheres

Toshiyuki Sugawa, Tanran Zhang

We define a distance function on the bordered punctured disk $0 < ∣ z ∣ \leq 1/ e$ in the complex plane, which is comparable with the hyperbolic distance of the punctured unit disk $0<|z|…

math.CV2017

A construction of trivial Beltrami coefficients

Toshiyuki Sugawa

A measurable function $μ$ on the unit disk $D$ of the complex plane with $∥ μ ∥_{\infty} < 1$ is sometimes called a Beltrami coefficient. We say that $μ$ is trivial if it is t…

math.CV2017

Geometric properties of the shifted hypergeometric functions

Toshiyuki Sugawa, Li-Mei Wang

We will provide sufficient conditions for the shifted hypergeometric function $z_{2} F_{1} (a, b; c; z)$ to be a member of a specific subclass of starlike functions in terms of the complex…

math.CV2017

Spherical convexity and hyperbolic metric

Toshiyuki Sugawa

Let $Ω$ be a domain in $C$ with hyperbolic metric $λ_{Ω} (z) ∣ d z ∣$ of Gaussian curvature $- 4.$ Mejia and Minda proved in their 1990 paper that $Ω$ is (Euclidean) convex if and…

On the hyperbolic distance of n-times punctured spheres

Construction of nearly hyperbolic distance on punctured spheres

A construction of trivial Beltrami coefficients

Geometric properties of the shifted hypergeometric functions

Spherical convexity and hyperbolic metric

On the hyperbolic distance of $n$ -times punctured spheres