Hostname: page-component-cd9895bd7-q99xh Total loading time: 0 Render date: 2024-12-30T19:36:29.639Z Has data issue: false hasContentIssue false

THE SHARPNESS OF A CRITERION OF MACLANE FOR THE CLASS ${\cal A}$

Published online by Cambridge University Press:  25 March 2003

DAVID DRASIN
Affiliation:
Department of Mathematics, Purdue University, 150 North University Avenue, West Lafayette, IN 47907-2067, [email protected]
JANG-MEI WU
Affiliation:
Department of Mathematics, University of Illinois, 1409 W. Green Street, Urbana, IL 61801, [email protected]
Get access

Abstract

A holomorphic function defined in the unit disk $\Delta = \{z: |z|<1\}$ belongs to the MacLane class ${\cal A}$ if each point $\zeta$ of a dense subset of $\p \Delta$ is the endpoint of a curve $\gamma_{\zeta}$ (with

$\gamma_{\zeta}\setminus \zeta \subset \Delta)$ such that $f(z)$ tends to a limit (perhaps $\infty$) as $z \to \zeta$ on $\gamma_\zeta$. The classical Fatou theorem ensures that $f \in {\cal A}$ when $f$ is bounded. G. R. MacLane introduced ${\cal A}$ in [5], where he proved that $f \in {\cal A}$ if there is a set $E$ dense in $\p \Delta$ with \begin{equation}\int^1_0 (1-r) \log^+|f(re^{i\theta})| \, dr<\infty\qquad(\theta \in E).\end{equation}

For example, if $f$ is the modular function and $M(r)=\max_{|z|=r}|f(z)|$ its maximum modulus, then

$$\log M(r)\leq \log\frac{1}{1-r} +O(1),$$

so that (1.1) applies. An ample discussion of ${\cal A}$ is in [4, Chapter 10].

Keywords

Type
Notes and Papers
Copyright
The London Mathematical Society 2003

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)