## The Annals of Probability

- Ann. Probab.
- Volume 11, Number 4 (1983), 876-893.

### Occupation Time Limit Theorems for the Voter Model

J. Theodore Cox and David Griffeath

#### Abstract

Let $\{\eta^\theta_s(x)\}, s \geq 0, x \in Z^d$ be the basic voter model starting from product measure with density $\theta(0 < \theta < 1).$ We consider the asymptotic behavior, as $t \rightarrow \infty$, of the occupation time field $\{T^x_t\}_{x \in Z^d}$, where $T^x_t = \int^t_0 \eta^\theta_s(x) ds$. Our main result is that, properly scaled and normalized, the occupation time field has a (weak) limit field as $t \rightarrow \infty$, whose covariance structure we compute explicitly. This field is Gaussian in dimensions $d \geq 2$. It is not Gaussian in dimension one, but has an "explicit" representation in terms of a system of coalescing Brownian motions. We also prove that $\lim_{t \rightarrow \infty} T^x_t/t = \theta$ a.s. for $d \geq 2$ (the result is false for $d = 1$). A striking feature of the behavior of the occupation time field is its elaborate dimension dependence.

#### Article information

**Source**

Ann. Probab. Volume 11, Number 4 (1983), 876-893.

**Dates**

First available in Project Euclid: 19 April 2007

**Permanent link to this document**

http://projecteuclid.org/euclid.aop/1176993438

**Digital Object Identifier**

doi:10.1214/aop/1176993438

**Mathematical Reviews number (MathSciNet)**

MR714952

**Zentralblatt MATH identifier**

0527.60095

**JSTOR**

links.jstor.org

**Subjects**

Primary: 60K35: Interacting random processes; statistical mechanics type models; percolation theory [See also 82B43, 82C43]

**Keywords**

Voter model coalescing random walks occupation times central limit theorems strong laws moments semi-invariants Ursell functions

#### Citation

Cox, J. Theodore; Griffeath, David. Occupation Time Limit Theorems for the Voter Model. Ann. Probab. 11 (1983), no. 4, 876--893. doi:10.1214/aop/1176993438. http://projecteuclid.org/euclid.aop/1176993438.