Kernels of trace operators via fine continuity

Fuente: arXiv
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Autores principales: Hinz, Michael, Chandler-Wilde, Simon N., Hewett, David P.
Formato: Preprint
Publicado: 2025
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author Hinz, Michael
Chandler-Wilde, Simon N.
Hewett, David P.
author_facet Hinz, Michael
Chandler-Wilde, Simon N.
Hewett, David P.
contents We study traces of elements of fractional Sobolev spaces $H_p^α(\mathbb{R}^n)$ on closed subsets $Γ$ of $\mathbb{R}^n$, given as the supports of suitable measures $μ$. We prove that if these measures satisfy localized upper density conditions, then quasi continuous representatives vanish quasi everywhere on $Γ$ if and only if they vanish $μ$-almost everywhere on $Γ$. We use this result to characterize the kernel of the trace operator mapping from $H_p^α(\mathbb{R}^n)$ into the space of $μ$-equivalence classes of functions on $Γ$ as the closure of $C_c^\infty(\mathbb{R}^n\setminus Γ)$ in $H_p^α(\mathbb{R}^n)$. The measures do not have to satisfy a doubling condition. In particular, the set $Γ$ may be a finite union of closed sets having different Hausdorff dimensions. We provide corresponding results for fractional Sobolev spaces $H_p^α(Ω)$ on domains $Ω\subset \mathbb{R}^n$ satisfying the measure density condition.
format Preprint
id arxiv_https___arxiv_org_abs_2507_04536
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Kernels of trace operators via fine continuity
Hinz, Michael
Chandler-Wilde, Simon N.
Hewett, David P.
Functional Analysis
Numerical Analysis
Analysis of PDEs
28A12, 28A75, 28A80, 31B15, 31C40, 46E35, 46N40
We study traces of elements of fractional Sobolev spaces $H_p^α(\mathbb{R}^n)$ on closed subsets $Γ$ of $\mathbb{R}^n$, given as the supports of suitable measures $μ$. We prove that if these measures satisfy localized upper density conditions, then quasi continuous representatives vanish quasi everywhere on $Γ$ if and only if they vanish $μ$-almost everywhere on $Γ$. We use this result to characterize the kernel of the trace operator mapping from $H_p^α(\mathbb{R}^n)$ into the space of $μ$-equivalence classes of functions on $Γ$ as the closure of $C_c^\infty(\mathbb{R}^n\setminus Γ)$ in $H_p^α(\mathbb{R}^n)$. The measures do not have to satisfy a doubling condition. In particular, the set $Γ$ may be a finite union of closed sets having different Hausdorff dimensions. We provide corresponding results for fractional Sobolev spaces $H_p^α(Ω)$ on domains $Ω\subset \mathbb{R}^n$ satisfying the measure density condition.
title Kernels of trace operators via fine continuity
topic Functional Analysis
Numerical Analysis
Analysis of PDEs
28A12, 28A75, 28A80, 31B15, 31C40, 46E35, 46N40
url https://arxiv.org/abs/2507.04536