On blow-ups of sets with finite fractional variation
Giorgio Stefani
TL;DR
This work investigates the infinitesimal geometry of sets with locally finite fractional α-variation by coupling the fractional BV framework with tangent-measure theory. Using a Preiss–Mattila style analysis of tangent measures and their iterates, the authors derive a rigidity result: for $|D^α 1_E|$-almost every point on the fractional reduced boundary $\mathscr F^α E$, any nontrivial tangent with locally finite integer perimeter must be a half-space oriented by the fractional inner normal $ν_E^α(x)$. This extends De Giorgi-type blow-up phenomena to the fractional setting and provides a precise infinitesimal model for the geometry of fractional perimeters. The results illuminate the structure of tangent sets in fractional BV theory and suggest robust rigidity under mild fractional BV hypotheses, with potential implications for rectifiability and fractional perimeter analysis.
Abstract
Given $α\in(0,1)$ and a set $E\subset\mathbb{R}^N$ with locally finite fractional $α$-variation, we show that for $|D^α\mathbf 1_E|$-a.e. $x$, every non-trivial tangent set of $E$ at $x$ with locally finite integer perimeter is a half-space oriented by the fractional inner unit normal of $E$ at $x$.
