Quasiminimal surfaces of codimension 1 and John domains
We study subsets \(E\) of codimension 1 of an annulus (say) in \(\mathbb{R}^n\) that separate the inside of the annulus from the outside and quasiminimize \((n-1)\)-dimensional Hausdorff measure, and the analogue of these sets in the context of BV and sets of finite perimeter. We show that quasiminimizers are uniformly rectifiable and Ahlfors-regular, and that their complement in \(\mathbb{R}^n\) is composed of two (connected) John domains with common boundary \(E\). In fact, these conditions characterize quasiminimizers. As an application we show that sets with not too large \((n-1)\)-dimensional Hausdorff measure which separate points in a definite way must contain a substantial piece of Lipschitz graph [see also \textit{P. W. Jones, N. W. Katz} and \textit{A. Vargas}, Rev. Mat. Iberoam. 13, No. 1, 189-210 (1997; Zbl 0908.49029)]. In this way we use area quasiminimizers to solve a problem in geometric measure theory.
scientific article; zbMATH DE number 1060830