On estimates of the Bourgain-Brezis-Mironescu type in the singular context
Roman D. Oleinik
TL;DR
This work advances BBM-type characterizations to the singular setting of metric measure spaces by broadening the mollifier class to include non-monotone families and by treating maps valued in arbitrary metric spaces. The authors leverage Cheeger energy, metric-valued Sobolev calculus, and a robust doubling–Poincaré framework to establish two-sided comparisons between the limiting nonlocal functional and the $p$-energy $E_p[f](O)$, up to a universal constant $C$. They introduce a flexible notion of $p$-admissible mollifiers, provide simplified, verifiable conditions, and verify admissibility for several explicit mollifier families, including nonmonotone examples. The results extend previous BBM-type analyses (LPZ22, O25) to broader mollifier classes and metric-valued targets, enabling nonlocal-to-local energy characterizations in highly non-smooth contexts and with potential applications to geometric analysis and nonlinear potential theory.
Abstract
We extend the characterization of the Bourgain-Brezis-Mironescu type for maps from certain metric measure spaces to arbitrary metric spaces to a broader class of mollifiers.
