Quantitative harmonic approximations and Dorronsoro's Theorem in metric measure spaces

Fuente: arXiv
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Main Author: Hyde, Matthew
Format: Preprint
Published: 2026
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author Hyde, Matthew
author_facet Hyde, Matthew
contents Suppose $X$ is an $\rm{RCD}(K,N)$ space with $K \in \mathbb{R}$ and $N \in (1,\infty)$. We obtain a characterisation of the Newtonian-Sobolev space $N^{1,2}(X)$ in terms of a quantity which measures to what extent a function is locally (across all scales and locations) well-approximated by harmonic functions. A similar characterisation is obtained which further takes into account the local oscillations of the approximating harmonic functions. The first characterisation is new even when $X = \mathbb{R}^n$; the second characterisation is a version of Dorronsoro's Theorem in RCD spaces and gives a new proof of (a special case) of this theorem in Euclidean space.
format Preprint
id arxiv_https___arxiv_org_abs_2603_17590
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quantitative harmonic approximations and Dorronsoro's Theorem in metric measure spaces
Hyde, Matthew
Classical Analysis and ODEs
Metric Geometry
Suppose $X$ is an $\rm{RCD}(K,N)$ space with $K \in \mathbb{R}$ and $N \in (1,\infty)$. We obtain a characterisation of the Newtonian-Sobolev space $N^{1,2}(X)$ in terms of a quantity which measures to what extent a function is locally (across all scales and locations) well-approximated by harmonic functions. A similar characterisation is obtained which further takes into account the local oscillations of the approximating harmonic functions. The first characterisation is new even when $X = \mathbb{R}^n$; the second characterisation is a version of Dorronsoro's Theorem in RCD spaces and gives a new proof of (a special case) of this theorem in Euclidean space.
title Quantitative harmonic approximations and Dorronsoro's Theorem in metric measure spaces
topic Classical Analysis and ODEs
Metric Geometry
url https://arxiv.org/abs/2603.17590