Trace operator on H 1 ($Ω$) for general open bounded domains

Fuente: arXiv
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Main Authors: Eymard, Robert, Gallouët, Thierry, Maltese, David, Vincent, Yannick
Format: Preprint
Published: 2025
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author Eymard, Robert
Gallouët, Thierry
Maltese, David
Vincent, Yannick
author_facet Eymard, Robert
Gallouët, Thierry
Maltese, David
Vincent, Yannick
contents In the case of any bounded open set $Ω$ $\subset$ R d with boundary $\partial$$Ω$, we first construct a directional trace in any direction $θ$ of the unit sphere, for any u $\in$ L 2 ($Ω$) whose the directional derivative $\partial$ $θ$ u in the direction $θ$ belongs to L 2 ($Ω$). This directional trace is shown to belong to L 2 ($\partial$$Ω$, $μ$ $θ$ ), where $μ$ $θ$ is a measure supported by the closure of all points of $\partial$$Ω$ which are the extremity of an open segment directed by $θ$, included in $Ω$. This trace enables an integration by parts formula. We then show that the set H 1 tr ($Ω$) containing the elements of H 1 ($Ω$) whose the directional trace does not depend on $θ$ is closed. It therefore contains the closure of H 1 ($Ω$) $\cap$ C 0 ($Ω$) in H 1 ($Ω$). Examples where H 1 tr ($Ω$) = H 1 ($Ω$) and H 1 tr ($Ω$) __ = H 1 ($Ω$) are provided.
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id arxiv_https___arxiv_org_abs_2502_02107
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publishDate 2025
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spellingShingle Trace operator on H 1 ($Ω$) for general open bounded domains
Eymard, Robert
Gallouët, Thierry
Maltese, David
Vincent, Yannick
Functional Analysis
In the case of any bounded open set $Ω$ $\subset$ R d with boundary $\partial$$Ω$, we first construct a directional trace in any direction $θ$ of the unit sphere, for any u $\in$ L 2 ($Ω$) whose the directional derivative $\partial$ $θ$ u in the direction $θ$ belongs to L 2 ($Ω$). This directional trace is shown to belong to L 2 ($\partial$$Ω$, $μ$ $θ$ ), where $μ$ $θ$ is a measure supported by the closure of all points of $\partial$$Ω$ which are the extremity of an open segment directed by $θ$, included in $Ω$. This trace enables an integration by parts formula. We then show that the set H 1 tr ($Ω$) containing the elements of H 1 ($Ω$) whose the directional trace does not depend on $θ$ is closed. It therefore contains the closure of H 1 ($Ω$) $\cap$ C 0 ($Ω$) in H 1 ($Ω$). Examples where H 1 tr ($Ω$) = H 1 ($Ω$) and H 1 tr ($Ω$) __ = H 1 ($Ω$) are provided.
title Trace operator on H 1 ($Ω$) for general open bounded domains
topic Functional Analysis
url https://arxiv.org/abs/2502.02107