On $q$-convex hypersurfaces in Riemannian manifolds

Fuente: arXiv
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Main Authors: Colombo, Giulio, Onti, Christos-Raent
Format: Preprint
Published: 2026
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author Colombo, Giulio
Onti, Christos-Raent
author_facet Colombo, Giulio
Onti, Christos-Raent
contents We prove that any closed, convex hypersurface in an $(n+1)$-dimensional Riemannian manifold with $\lceil \frac{n}{2} \rceil$-positive curvature operator is a rational homology sphere with finite fundamental group. The same conclusion holds for any $\lceil \frac{n}{2} \rceil$-convex hypersurface, provided that the mean curvature satisfies a sharp pinching condition. Both results follow from more general vanishing and estimation theorems for the Betti numbers of closed $q$-convex immersed hypersurfaces in $(n+1)$-dimensional Riemannian manifolds, under a lower bound on the average of the smallest $(n-p)$ eigenvalues of the curvature operator.
format Preprint
id arxiv_https___arxiv_org_abs_2604_20695
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On $q$-convex hypersurfaces in Riemannian manifolds
Colombo, Giulio
Onti, Christos-Raent
Differential Geometry
53C40, 53C42, 53C20, 53C21
We prove that any closed, convex hypersurface in an $(n+1)$-dimensional Riemannian manifold with $\lceil \frac{n}{2} \rceil$-positive curvature operator is a rational homology sphere with finite fundamental group. The same conclusion holds for any $\lceil \frac{n}{2} \rceil$-convex hypersurface, provided that the mean curvature satisfies a sharp pinching condition. Both results follow from more general vanishing and estimation theorems for the Betti numbers of closed $q$-convex immersed hypersurfaces in $(n+1)$-dimensional Riemannian manifolds, under a lower bound on the average of the smallest $(n-p)$ eigenvalues of the curvature operator.
title On $q$-convex hypersurfaces in Riemannian manifolds
topic Differential Geometry
53C40, 53C42, 53C20, 53C21
url https://arxiv.org/abs/2604.20695