Euler Characteristic of Closed Manifolds with Almost Nonnegative Curvature Operator

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1. Verfasser: Cai, Jing-Bin
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Veröffentlicht: 2026
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author Cai, Jing-Bin
author_facet Cai, Jing-Bin
contents We study closed manifolds with almost nonnegative curvature operator and address a question of Herrmann--Sebastian--Tuschmann concerning the sign of their Euler characteristic. Our main result shows that if a closed $2n$-dimensional manifold admits an almost nonnegative curvature operator together with a uniform upper bound on the curvature operator, then its Euler characteristic is nonnegative. In addition, under an ANCO-type condition and assuming that the fundamental group is infinite, we prove vanishing results for the Euler characteristic, the signature, and, in the spin case, the $\widehat{A}$-genus, extending recent work of Chen--Ge--Han from almost nonnegative Ricci curvature to the curvature-operator setting.
format Preprint
id arxiv_https___arxiv_org_abs_2603_23932
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Euler Characteristic of Closed Manifolds with Almost Nonnegative Curvature Operator
Cai, Jing-Bin
Differential Geometry
53C21 (Primary), 53C20, 53C24 (Secondary)
We study closed manifolds with almost nonnegative curvature operator and address a question of Herrmann--Sebastian--Tuschmann concerning the sign of their Euler characteristic. Our main result shows that if a closed $2n$-dimensional manifold admits an almost nonnegative curvature operator together with a uniform upper bound on the curvature operator, then its Euler characteristic is nonnegative. In addition, under an ANCO-type condition and assuming that the fundamental group is infinite, we prove vanishing results for the Euler characteristic, the signature, and, in the spin case, the $\widehat{A}$-genus, extending recent work of Chen--Ge--Han from almost nonnegative Ricci curvature to the curvature-operator setting.
title Euler Characteristic of Closed Manifolds with Almost Nonnegative Curvature Operator
topic Differential Geometry
53C21 (Primary), 53C20, 53C24 (Secondary)
url https://arxiv.org/abs/2603.23932