The Singular Set of Higher Dimensional Unstable Obstacle Type Problems
arXiv:1207.3398
Abstract
In this paper we will investigate the singular points of the following unstable free boundary problem: {equation}\label{Eq} Îu= -Ï_{\{u>0\}} \quad\quad\textrm{in} B_1(0) {equation} where $Ï_{\{u>0\}}$ is the characteristic function of the set $\{u>0\}$.