The degree condition in Llarull's theorem on scalar curvature rigidity

Fuente: arXiv
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Auteurs principaux: Baer, Christian, Zeidler, Rudolf
Format: Preprint
Publié: 2025
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author Baer, Christian
Zeidler, Rudolf
author_facet Baer, Christian
Zeidler, Rudolf
contents Llarull's scalar curvature rigidity theorem states that a 1-Lipschitz map $f: M\to S^n$ from a closed connected Riemannian spin manifold $M$ with scalar curvature $\mathrm{scal}\ge n(n-1)$ to the standard sphere $S^n$ is an isometry if the degree of $f$ is nonzero. We investigate if one can replace the condition $\mathrm{deg}(f)\neq0$ by the weaker condition that $f$ is surjective. The answer turns out to be "no" for $n\ge3$ but "yes" for $n=2$. If we replace the scalar curvature by Ricci curvature, the answer is "yes" in all dimensions.
format Preprint
id arxiv_https___arxiv_org_abs_2507_05459
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The degree condition in Llarull's theorem on scalar curvature rigidity
Baer, Christian
Zeidler, Rudolf
Differential Geometry
53C20, 53C24
Llarull's scalar curvature rigidity theorem states that a 1-Lipschitz map $f: M\to S^n$ from a closed connected Riemannian spin manifold $M$ with scalar curvature $\mathrm{scal}\ge n(n-1)$ to the standard sphere $S^n$ is an isometry if the degree of $f$ is nonzero. We investigate if one can replace the condition $\mathrm{deg}(f)\neq0$ by the weaker condition that $f$ is surjective. The answer turns out to be "no" for $n\ge3$ but "yes" for $n=2$. If we replace the scalar curvature by Ricci curvature, the answer is "yes" in all dimensions.
title The degree condition in Llarull's theorem on scalar curvature rigidity
topic Differential Geometry
53C20, 53C24
url https://arxiv.org/abs/2507.05459