Spaces with Riemannian curvature bounds are universally infinitesimally Hilbertian

Fuente: arXiv
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Auteurs principaux: Núñez-Zimbrón, Jesús, Pasqualetto, Enrico, Soultanis, Elefterios
Format: Preprint
Publié: 2025
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author Núñez-Zimbrón, Jesús
Pasqualetto, Enrico
Soultanis, Elefterios
author_facet Núñez-Zimbrón, Jesús
Pasqualetto, Enrico
Soultanis, Elefterios
contents We show that a metric space $X$ that, at every point, has a Gromov-Hausdorff tangent with the splitting property (i.e. every geodesic line splits off a factor $\mathbb{R}$), is universally infinitesimally Hilbertian (i.e. $W^{1,2}(X,μ)$ is a Hilbert space for every measure $μ$). This connects the infinitesimal geometry of $X$ to its analytic properties and is, to our knowledge, the first general criterion guaranteeing universal infinitesimal Hilbertianity. Using it we establish universal infinitesimal Hilbertianity of finite dimensional RCD-spaces. We moreover show that (possibly infinite dimensional) Alexandrov spaces are universally infinitesimally Hilbertian and construct an isometric embedding of tangent modules.
format Preprint
id arxiv_https___arxiv_org_abs_2508_05483
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Spaces with Riemannian curvature bounds are universally infinitesimally Hilbertian
Núñez-Zimbrón, Jesús
Pasqualetto, Enrico
Soultanis, Elefterios
Metric Geometry
Differential Geometry
Functional Analysis
46E36, 51F99, 49J52, 53C23
We show that a metric space $X$ that, at every point, has a Gromov-Hausdorff tangent with the splitting property (i.e. every geodesic line splits off a factor $\mathbb{R}$), is universally infinitesimally Hilbertian (i.e. $W^{1,2}(X,μ)$ is a Hilbert space for every measure $μ$). This connects the infinitesimal geometry of $X$ to its analytic properties and is, to our knowledge, the first general criterion guaranteeing universal infinitesimal Hilbertianity. Using it we establish universal infinitesimal Hilbertianity of finite dimensional RCD-spaces. We moreover show that (possibly infinite dimensional) Alexandrov spaces are universally infinitesimally Hilbertian and construct an isometric embedding of tangent modules.
title Spaces with Riemannian curvature bounds are universally infinitesimally Hilbertian
topic Metric Geometry
Differential Geometry
Functional Analysis
46E36, 51F99, 49J52, 53C23
url https://arxiv.org/abs/2508.05483