On the growth and coefficients of analytic functions
type: Item
instance of: scholarly article
title: On the growth and coefficients of analytic functions
zbMATH Open document ID: 0567.30020
DOI: 10.2307/1971085
published in: Annals of Mathematics. Second Series
publication date: 1984-01-01T00:00:00Z
review text: Suppose that \(\Omega\) is a plane domain such that \({\mathbb{C}}| \Omega\) is infinite. Hayman, Pommerenke, and Patterson proved that the universal covering map F from the unit disk \(\Delta\) onto \(\Omega\) satisfies \(S(r,F)=o(1-r)^{-1}\), where S(r,f) denotes the spherical area counting multiplicities of the image of F under \(| z| \leq r\). They conjectured the same bound would hold for any analytic \(f: \Delta\) \(\to \Omega\). Here the author, via an exceedingly ingenious iterative construction, shows the HPP conjecture is false. In fact, as long as \(cap({\mathbb{C}}| \Omega)=0\) there exists \(f: \Delta\) \(\to \Omega\) such that \(S(r,f)\neq o(1-r)^{-1}.\) This gives a new characterization of sets of capacity zero. The same construction also settles negatively a longstanding question about coefficients of Bloch functions: If \(cap({\mathbb{C}}| \Omega)=0\) there exists \(f: \Delta\) \(\to \Omega\) for which \(a_ n\neq O(1).\) The author has used a related construction to settle affirmatively a question of Hayman about the relation between Nevanlinna's proximity function and sets of given Hausdorff dimension [J. Lond. Math. Soc., II. Ser. 30, 79-86 (1984; Zbl 0561.30024)].
Mathematics Subject Classification ID: 30C99
zbMATH DE Number: 3904926
zbMATH Keywords: Bloch functions
zbMATH Keywords: Hausdorff dimension
author: J. L. Fernández
reviewed by: Albert Baernstein II
MaRDI profile type: Publication
full work available at URL: https://doi.org/10.2307/1971085
OpenAlex ID: W2334844677
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description: scientific article; zbMATH DE number 3904926