# DICHOTOMY OF GLOBAL CAPACITY DENSITY IN METRIC MEASURE SPACES

created by shanmugal on 08 Jan 2017
modified on 13 Oct 2018

[BibTeX]

Published Paper

Inserted: 8 jan 2017
Last Updated: 13 oct 2018

Volume: 11
Number: 4
Pages: 387--404
Year: 2016

Abstract:

The variational capacity $\text{cap}_p$ in Euclidean spaces is known to enjoy the density dichotomy at large scales, namely that for every $E\subset\mathbb{R}^n$, $\inf_{x\in\mathbb{R}^n}\frac{\text{cap}_p(E\cap B(x,r),B(x,2r))}{\text{cap}_p(B(x,r),B(x,2r))}$ is either zero or tends to $1$ as $r \to \infty$. We prove that this property still holds in unbounded complete geodesic metric spaces equipped with a doubling measure supporting a \p-Poincar\'e inequality, but that it can fail in nongeodesic metric spaces and also for the Sobolev capacity in $\mathbb{R}^n$.

It turns out that the shape of balls impacts the validity of the density dichotomy. Even in more general metric spaces, we construct families of sets, such as John domains, for which the density dichotomy holds. Our arguments include an exact formula for the variational capacity of superlevel sets for capacitary potentials and a quantitative approximation from inside of the variational capacity.