## The Annals of Probability

- Ann. Probab.
- Volume 7, Number 6 (1979), 913-932.

### Brownian Motion and Analytic Functions

#### Abstract

This paper is mostly expository and is concerned with the connection between two dimensional Brownian motion and analytic functions provided by Levy's result that, if $Z_t, 0 \leqslant t < \infty$, is two dimensional Brownian motion, and if $f$ is analytic and not constant, then $f(Z_t), 0 \leqslant t < \infty$, is also two dimensional Brownian motion, perhaps moving at a variable speed. This can be used to study Brownian motion via analytic functions and, conversely, to treat analytic functions probabilistically. Recently several open problems in analytic function theory have been solved in this manner. We will present some of Doob's earlier work on the range and boundary values of analytic functions, the probabilistic theory of $H^p$ spaces due to Burkholder, Gundy and Silverstein, the author's results on conjugate function inequalities. and sketch probabilistic proofs of Picard's big and little theorems, and other theorems. There are some new results related to Hayman's generalization of Koebe's theorem.

#### Article information

**Source**

Ann. Probab. Volume 7, Number 6 (1979), 913-932.

**Dates**

First available in Project Euclid: 19 April 2007

**Permanent link to this document**

http://projecteuclid.org/euclid.aop/1176994888

**JSTOR**

links.jstor.org

**Digital Object Identifier**

doi:10.1214/aop/1176994888

**Mathematical Reviews number (MathSciNet)**

MR548889

**Zentralblatt MATH identifier**

0421.60072

**Subjects**

Primary: 60J65: Brownian motion [See also 58J65]

Secondary: 30A78 42A40 42A36 30A70

**Keywords**

30-02 Analytic functions Brownian motion conjugate function Hardy spaces Picard's theorem nontangental maximal function

#### Citation

Davis, Burgess. Brownian Motion and Analytic Functions. Ann. Probab. 7 (1979), no. 6, 913--932. doi:10.1214/aop/1176994888. http://projecteuclid.org/euclid.aop/1176994888.