Free-Boundary Monotonicity for Almost-Minimizers of the Relative Perimeter

TL;DR

This paper establishes a free-boundary monotonicity inequality for almost-minimizers of the relative perimeter under a geometric 'visibility' condition, leading to existence of density and classification of blow-ups as perimeter-minimizing cones.

Contribution

It introduces a new free-boundary monotonicity inequality for almost-minimizers under the visibility condition, extending regularity results to non-smooth domains.

Findings

Proves a free-boundary monotonicity inequality under visibility.

Establishes the existence of perimeter density at boundary points.

Shows blow-ups are perimeter-minimizing cones within tangent cones.

Abstract

Let $E \subset \Omega$ be a local almost-minimizer of the relative perimeter in the open set $\Omega \subset \mathbb{R}^{n}$. We prove a free-boundary monotonicity inequality for $E$ at a point $x\in \partial\Omega$, under a geometric property called ``visibility'', that $\Omega$ is required to satisfy in a neighborhood of $x$. Incidentally, the visibility property is satisfied by a considerably large class of Lipschitz and possibly non-smooth domains. Then, we prove the existence of the density of the relative perimeter of $E$ at $x$, as well as the fact that any blow-up of $E$ at $x$ is necessarily a perimeter-minimizing cone within the tangent cone to $\Omega$ at $x$.