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Main Authors: Chen, Hua, Chen, Hong-Ge, Li, Jin-Ning
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2404.19393
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author Chen, Hua
Chen, Hong-Ge
Li, Jin-Ning
author_facet Chen, Hua
Chen, Hong-Ge
Li, Jin-Ning
contents Let $U$ be a connected open subset of $\mathbb{R}^n$, and let $X=(X_1,X_{2},\ldots,X_m)$ be a system of Hörmander vector fields defined on $U$. This paper addresses sharp embedding results and geometric inequalities in the generalized Sobolev space $\mathcal{W}_{X,0}^{k,p}(Ω)$, where $Ω\subset\subset U$ is a general open bounded subset of $U$. By employing Rothschild-Stein's lifting technique and saturation method, we prove the representation formula for smooth functions with compact support in $Ω$. Combining this representation formula with weighted weak-$L^p$ estimates, we derive sharp Sobolev inequalities on $\mathcal{W}_{X,0}^{k,p}(Ω)$, where the critical Sobolev exponent depends on the generalized Métivier index. As applications of these sharp Sobolev inequalities, we establish the isoperimetric inequality, logarithmic Sobolev inequalities, Rellich-Kondrachov compact embedding theorem, Gagliardo-Nirenberg inequality, Nash inequality, and Moser-Trudinger inequality in the context of general Hörmander vector fields.
format Preprint
id arxiv_https___arxiv_org_abs_2404_19393
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Sharp embedding results and geometric inequalities for Hörmander vector fields
Chen, Hua
Chen, Hong-Ge
Li, Jin-Ning
Analysis of PDEs
35J70, 35H20, 46E35
Let $U$ be a connected open subset of $\mathbb{R}^n$, and let $X=(X_1,X_{2},\ldots,X_m)$ be a system of Hörmander vector fields defined on $U$. This paper addresses sharp embedding results and geometric inequalities in the generalized Sobolev space $\mathcal{W}_{X,0}^{k,p}(Ω)$, where $Ω\subset\subset U$ is a general open bounded subset of $U$. By employing Rothschild-Stein's lifting technique and saturation method, we prove the representation formula for smooth functions with compact support in $Ω$. Combining this representation formula with weighted weak-$L^p$ estimates, we derive sharp Sobolev inequalities on $\mathcal{W}_{X,0}^{k,p}(Ω)$, where the critical Sobolev exponent depends on the generalized Métivier index. As applications of these sharp Sobolev inequalities, we establish the isoperimetric inequality, logarithmic Sobolev inequalities, Rellich-Kondrachov compact embedding theorem, Gagliardo-Nirenberg inequality, Nash inequality, and Moser-Trudinger inequality in the context of general Hörmander vector fields.
title Sharp embedding results and geometric inequalities for Hörmander vector fields
topic Analysis of PDEs
35J70, 35H20, 46E35
url https://arxiv.org/abs/2404.19393