Toshiyuki Sugawa

most citedUnivalence criteria and analogs of the John constant

1 citations · 1 across the 2 of their papers we have counts for

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math.CV2022

On geometric properties of ratio of two hypergeometric functions

Toshiyuki Sugawa, Li-Mei Wang

R. Küstner proved in his 2002 paper that the function $w_{a, b, c} (z) =$ $F (a + 1, b; c; z) / F (a, b; c; z)$ maps the unit disk $∣ z ∣ < 1$ onto a domain convex in the direction of the imaginary ax…

math.CV2012★ 1 cited

Univalence criteria and analogs of the John constant

Yong Chan Kim, Toshiyuki Sugawa

Let $p (z) = z f^{'} (z) / f (z)$ for a function $f (z)$ analytic on the unit disk $∣ z ∣ < 1$ in the complex plane and normalized by $f (0) = 0, f^{'} (0) = 1.$ We will provide lower and upper bounds for…