Non-collapsed eGH convergence and dimension

Fuente: arXiv
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Main Authors: Núñez-Zimbrón, Jesús, Santos-Rodríguez, Jaime, Zamora, Sergio
Format: Preprint
Published: 2025
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author Núñez-Zimbrón, Jesús
Santos-Rodríguez, Jaime
Zamora, Sergio
author_facet Núñez-Zimbrón, Jesús
Santos-Rodríguez, Jaime
Zamora, Sergio
contents Let $(X_i,p_i)$ be a non-collapsing sequence of pointed $n$-dimensional Riemannian manifolds with a uniform lower Ricci curvature bound, and $G_i \leq \text{Iso} (X_i)$ a sequence of closed subgroups of isometries. We show that if the triples $(X_i, G_i, p_i)$ converge in the equivariant Gromov--Hausdorff sense to a triple $(X,G,p)$, then $\text{dim} (G) \geq \limsup _{i \to \infty} \text{dim} (G_i)$, generalizing a result of Harvey to the non-compact setting. The argument also applies in the non-smooth setting of RCD spaces. As an application, we investigate RCD spaces with large isometry groups, extending results of Galaz-García--Kell--Mondino--Sosa and Galaz-García--Guijarro.
format Preprint
id arxiv_https___arxiv_org_abs_2509_22821
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Non-collapsed eGH convergence and dimension
Núñez-Zimbrón, Jesús
Santos-Rodríguez, Jaime
Zamora, Sergio
Differential Geometry
Metric Geometry
53C23, 53C21
Let $(X_i,p_i)$ be a non-collapsing sequence of pointed $n$-dimensional Riemannian manifolds with a uniform lower Ricci curvature bound, and $G_i \leq \text{Iso} (X_i)$ a sequence of closed subgroups of isometries. We show that if the triples $(X_i, G_i, p_i)$ converge in the equivariant Gromov--Hausdorff sense to a triple $(X,G,p)$, then $\text{dim} (G) \geq \limsup _{i \to \infty} \text{dim} (G_i)$, generalizing a result of Harvey to the non-compact setting. The argument also applies in the non-smooth setting of RCD spaces. As an application, we investigate RCD spaces with large isometry groups, extending results of Galaz-García--Kell--Mondino--Sosa and Galaz-García--Guijarro.
title Non-collapsed eGH convergence and dimension
topic Differential Geometry
Metric Geometry
53C23, 53C21
url https://arxiv.org/abs/2509.22821