A gap condition for the zeroes of certain polynomials in Kaplan classes K(α, β)

Mathematika ◽  
1987 ◽  
Vol 34 (1) ◽  
pp. 53-63 ◽  
Author(s):  
Massoud Jahangiri
Keyword(s):  
Author(s):  
Szymon Ignaciuk ◽  
Maciej Parol

In this article we consider the problem of univalence of a function introduced by Breaz and Ularu, improve some of their results and receive not only univalence conditions but also close-to-convex conditions for this function. To this aim, we used our method based on Kaplan classes.


2020 ◽  
Vol 46 (4) ◽  
pp. 769-779
Author(s):  
Sz. Ignaciuk ◽  
M. Parol

Author(s):  
Szymon Ignaciuk ◽  
Maciej Parol

We give the complete characterization of members of Kaplan classes of products of power functions with all zeros symmetrically distributed in \(\mathbb{T} := \{z \in\mathbb{C} : |z| = 1\}\) and weakly monotonic sequence of powers. In this way we extend Sheil-Small’s theorem. We apply the obtained result to study univalence of antiderivative of these products of power functions.


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