Self-improvement of fractional Hardy inequalities in metric measure spaces via hyperbolic fillings

Fuente: arXiv
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Main Authors: Eriksson-Bique, Sylvester, Kline, Josh
Format: Preprint
Published: 2024
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author Eriksson-Bique, Sylvester
Kline, Josh
author_facet Eriksson-Bique, Sylvester
Kline, Josh
contents In this paper, we prove a self-improvement result for $(θ,p)$-fractional Hardy inequalities, in both the exponent $1<p<\infty$ and the regularity parameter $0<θ<1$, for bounded domains in doubling metric measure spaces. The key conceptual tool is a Caffarelli-Silvestre-type argument, which relates fractional Sobolev spaces on $Z$ to Newton-Sobolev spaces in the hyperbolic filling $\overline{X}_{\varepsilon}$ of $Z$ via trace results. Using this insight, it is shown that a fractional Hardy inequality in an open subset of $Z$ is equivalent to a classical Hardy inequality in the filling $\overline{X}_{\varepsilon}$. The main result is then obtained by applying a new weighted self-improvement result for $p$-Hardy inequalities. The exponent $p$ can be self-improved by a classical Koskela-Zhong argument, but a new theory of regularizable weights is developed to obtain the self-improvement in the regularity parameter $θ$. This generalizes a result of Lehrbäck and Koskela on self-improvement of $d_Ω^β$-weighted $p$-Hardy inequalities by allowing a much broader class of weights. Using the equivalence of fractional Hardy inequalities with Hardy inequalities in the fillings, we also give new examples of domains satisfying fractional Hardy inequalities.
format Preprint
id arxiv_https___arxiv_org_abs_2412_02848
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Self-improvement of fractional Hardy inequalities in metric measure spaces via hyperbolic fillings
Eriksson-Bique, Sylvester
Kline, Josh
Analysis of PDEs
Classical Analysis and ODEs
Metric Geometry
35R11, (26D10, 28A75, 30L15, 31C15, 31E05, 35A23, 46E35)
In this paper, we prove a self-improvement result for $(θ,p)$-fractional Hardy inequalities, in both the exponent $1<p<\infty$ and the regularity parameter $0<θ<1$, for bounded domains in doubling metric measure spaces. The key conceptual tool is a Caffarelli-Silvestre-type argument, which relates fractional Sobolev spaces on $Z$ to Newton-Sobolev spaces in the hyperbolic filling $\overline{X}_{\varepsilon}$ of $Z$ via trace results. Using this insight, it is shown that a fractional Hardy inequality in an open subset of $Z$ is equivalent to a classical Hardy inequality in the filling $\overline{X}_{\varepsilon}$. The main result is then obtained by applying a new weighted self-improvement result for $p$-Hardy inequalities. The exponent $p$ can be self-improved by a classical Koskela-Zhong argument, but a new theory of regularizable weights is developed to obtain the self-improvement in the regularity parameter $θ$. This generalizes a result of Lehrbäck and Koskela on self-improvement of $d_Ω^β$-weighted $p$-Hardy inequalities by allowing a much broader class of weights. Using the equivalence of fractional Hardy inequalities with Hardy inequalities in the fillings, we also give new examples of domains satisfying fractional Hardy inequalities.
title Self-improvement of fractional Hardy inequalities in metric measure spaces via hyperbolic fillings
topic Analysis of PDEs
Classical Analysis and ODEs
Metric Geometry
35R11, (26D10, 28A75, 30L15, 31C15, 31E05, 35A23, 46E35)
url https://arxiv.org/abs/2412.02848