## Annals of Probability

### Brownian motion on some spaces with varying dimension

#### Abstract

In this paper, we introduce and study Brownian motion on a class of state spaces with varying dimension. Starting with a concrete case of such state spaces that models a big square with a flag pole, we construct a Brownian motion on it and study how heat propagates on such a space. We derive sharp two-sided global estimates on its transition density function (also called heat kernel). These two-sided estimates are of Gaussian type, but the measure on the underlying state space does not satisfy volume doubling property. Parabolic Harnack inequality fails for such a process. Nevertheless, we show Hölder regularity holds for its parabolic functions. We also derive the Green function estimates for this process on bounded smooth domains. Brownian motion on some other state spaces with varying dimension are also constructed and studied in this paper.

#### Article information

Source
Ann. Probab., Volume 47, Number 1 (2019), 213-269.

Dates
Revised: October 2017
First available in Project Euclid: 13 December 2018

https://projecteuclid.org/euclid.aop/1544691621

Digital Object Identifier
doi:10.1214/18-AOP1260

Mathematical Reviews number (MathSciNet)
MR3909969

Zentralblatt MATH identifier
07036337

#### Citation

Chen, Zhen-Qing; Lou, Shuwen. Brownian motion on some spaces with varying dimension. Ann. Probab. 47 (2019), no. 1, 213--269. doi:10.1214/18-AOP1260. https://projecteuclid.org/euclid.aop/1544691621

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