Characterizing rectifiability via biLipschitz pieces of Lipschitz mappings on the space

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Hauptverfasser: Li, Sean, Schul, Raanan
Format: Preprint
Veröffentlicht: 2025
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author Li, Sean
Schul, Raanan
author_facet Li, Sean
Schul, Raanan
contents We give the following characterization of rectifiable metric spaces. A metric space with positive lower Hausdorff density is rectifiable if and only if, for any subset $F$ and $f:F\to Y$, a Lipschitz map into a metric space with positive measure image (of the same dimension), there exists a positive measure subset $A\subset F$ so that $f$ is biLipschitz on $A$. We also give a characterization in terms of a full biLipschitz decomposition. These characterizations are new even for subsets of Euclidean space. One of our tools is Alberti representations. On the way we give a method for constructing independent Alberti representations, which may be of independent interest. We use this to characterize unrectifiable metric spaces as those spaces for which there exist a positive measure subset $S$ and a Lipschitz map $ϕ$ into a lower dimensional Euclidean space so that $S$ is $\cH^1$-null with respect to all curve fragments that are quantitatively transversal to $ϕ$.
format Preprint
id arxiv_https___arxiv_org_abs_2510_13525
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Characterizing rectifiability via biLipschitz pieces of Lipschitz mappings on the space
Li, Sean
Schul, Raanan
Metric Geometry
Classical Analysis and ODEs
We give the following characterization of rectifiable metric spaces. A metric space with positive lower Hausdorff density is rectifiable if and only if, for any subset $F$ and $f:F\to Y$, a Lipschitz map into a metric space with positive measure image (of the same dimension), there exists a positive measure subset $A\subset F$ so that $f$ is biLipschitz on $A$. We also give a characterization in terms of a full biLipschitz decomposition. These characterizations are new even for subsets of Euclidean space. One of our tools is Alberti representations. On the way we give a method for constructing independent Alberti representations, which may be of independent interest. We use this to characterize unrectifiable metric spaces as those spaces for which there exist a positive measure subset $S$ and a Lipschitz map $ϕ$ into a lower dimensional Euclidean space so that $S$ is $\cH^1$-null with respect to all curve fragments that are quantitatively transversal to $ϕ$.
title Characterizing rectifiability via biLipschitz pieces of Lipschitz mappings on the space
topic Metric Geometry
Classical Analysis and ODEs
url https://arxiv.org/abs/2510.13525