Published Paper

Inserted: 11 jul 2024
Last Updated: 29 sep 2025

Journal: Nonlinear Anal.
Volume: 263
Pages: Paper No. 113948
Year: 2026

Abstract:

We give a partial negative answer to a question left open in a previous work by Brasco and the first and third-named authors concerning the sharp constant in the fractional Hardy inequality on convex sets. Our approach has a geometrical flavor and equivalently reformulates the sharp constant in the limit case $p=1$ as the Cheeger constant for the fractional perimeter and the Lebesgue measure with a suitable weight. As a by-product, we obtain new lower bounds on the sharp constant in the $1$-dimensional case, even for non-convex sets, some of which optimal in the case $p=1$.

Keywords: fractional Sobolev spaces, Hardy inequality, fractional perimeter

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• Bianchi, Stefani, Zagati - A geometrical approach to the sharp Hardy inequality in Sobolev-Slobodeckii spaces