English

On Becker's univalence criterion

Complex Variables 2017-05-17 v1

Abstract

We study locally univalent functions ff analytic in the unit disc D\mathbb{D} of the complex plane such that f"(z)/f(z)(1z2)1+C(1z)|{f"(z)/f'(z)}|(1-|z|^2)\leq 1+C(1-|z|) holds for all zDz\in\mathbb{D}, for some 0<C<0<C<\infty. If C1C\leq 1, then ff is univalent by Becker's univalence criterion. We discover that for 1<C<1<C<\infty the function ff remains to be univalent in certain horodiscs. Sufficient conditions which imply that ff is bounded, belongs to the Bloch space or belongs to the class of normal functions, are discussed. Moreover, we consider generalizations for locally univalent harmonic functions.

Keywords

Cite

@article{arxiv.1705.05738,
  title  = {On Becker's univalence criterion},
  author = {Juha-Matti Huusko and Toni Vesikko},
  journal= {arXiv preprint arXiv:1705.05738},
  year   = {2017}
}

Comments

14 pages, 1 figure

R2 v1 2026-06-22T19:48:39.344Z