Approximation by regular functions in Sobolev spaces arising from doubly elliptic problems

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Hauptverfasser: Pucci, Patrizia, Vitillaro, Enzo
Format: Preprint
Veröffentlicht: 2020
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author Pucci, Patrizia
Vitillaro, Enzo
author_facet Pucci, Patrizia
Vitillaro, Enzo
contents The paper deals with a nontrivial density result for $C^m(\overlineΩ)$ functions, with $m\in{\mathbb N}\cup\{\infty\}$, in the space $$W^{k,\ell,p}(Ω;Γ)= \left\{u\in W^{k,p}(Ω): u_{|Γ}\in W^{\ell,p}(Γ)\right\},$$ endowed with the norm of $(u,u_{|Γ})$ in $W^{k,p}(Ω)\times W^{\ell,p}(Γ)$, where $Ω$ is a bounded open subset of ${\mathbb R}^N$, $N\ge 2$, with boundary $Γ$ of class $C^m$, $k\le \ell\le m$ and $1\le p<\infty$. Such a result is of interest when dealing with doubly elliptic problems involving two elliptic operators, one in $Ω$ and the other on $Γ$. Moreover we shall also consider the case when a Dirichlet homogeneous boundary condition is imposed on a relatively open part of $Γ$ and, as a preliminary step, we shall prove an analogous result when either $Ω={\mathbb R}^N$ or $Ω={\mathbb R}^N_+$ and $Γ=\partial{\mathbb R}^N_+$. \keywords{Density results\and Sobolev spaces \and Smooth functions \and the Laplace--Beltrami operator.
format Preprint
id arxiv_https___arxiv_org_abs_2005_10740
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle Approximation by regular functions in Sobolev spaces arising from doubly elliptic problems
Pucci, Patrizia
Vitillaro, Enzo
Analysis of PDEs
Functional Analysis
46E35 46.38 46M35
The paper deals with a nontrivial density result for $C^m(\overlineΩ)$ functions, with $m\in{\mathbb N}\cup\{\infty\}$, in the space $$W^{k,\ell,p}(Ω;Γ)= \left\{u\in W^{k,p}(Ω): u_{|Γ}\in W^{\ell,p}(Γ)\right\},$$ endowed with the norm of $(u,u_{|Γ})$ in $W^{k,p}(Ω)\times W^{\ell,p}(Γ)$, where $Ω$ is a bounded open subset of ${\mathbb R}^N$, $N\ge 2$, with boundary $Γ$ of class $C^m$, $k\le \ell\le m$ and $1\le p<\infty$. Such a result is of interest when dealing with doubly elliptic problems involving two elliptic operators, one in $Ω$ and the other on $Γ$. Moreover we shall also consider the case when a Dirichlet homogeneous boundary condition is imposed on a relatively open part of $Γ$ and, as a preliminary step, we shall prove an analogous result when either $Ω={\mathbb R}^N$ or $Ω={\mathbb R}^N_+$ and $Γ=\partial{\mathbb R}^N_+$. \keywords{Density results\and Sobolev spaces \and Smooth functions \and the Laplace--Beltrami operator.
title Approximation by regular functions in Sobolev spaces arising from doubly elliptic problems
topic Analysis of PDEs
Functional Analysis
46E35 46.38 46M35
url https://arxiv.org/abs/2005.10740