Characterizations of $p$-superharmonic functions on metric spaces
Volume 169 / 2005
Studia Mathematica 169 (2005), 45-62
MSC: Primary 31C45; Secondary 31C05, 35J60, 49J27.
DOI: 10.4064/sm169-1-3
Abstract
We show the equivalence of some different definitions of $p$-superharmonic functions given in the literature. We also provide several other characterizations of $p$-superharmonicity. This is done in complete metric spaces equipped with a doubling measure and supporting a Poincaré inequality. There are many examples of such spaces. A new one given here is the union of a line (with the one-dimensional Lebesgue measure) and a triangle (with a two-dimensional weighted Lebesgue measure). Our results also apply to Cheeger $p$-superharmonic functions and in the Euclidean setting to $\cal A$-superharmonic functions, with the usual assumptions on $\cal A$.