A partitioned manifold index theorem for noncompact hypersurfaces

Fuente: arXiv
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Hauptverfasser: Hochs, Peter, de Kok, Thijs
Format: Preprint
Veröffentlicht: 2025
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author Hochs, Peter
de Kok, Thijs
author_facet Hochs, Peter
de Kok, Thijs
contents Roe's partitioned manifold index theorem applies when a complete Riemannian manifold $M$ is cut into two pieces along a compact hypersurface $N$. It states that a version of the index of a Dirac operator on $M$ localized to $N$ equals the index of the corresponding Dirac operator on $N$. This yields obstructions to positive scalar curvature, and implies cobordism invariance of the index of Dirac operators on compact manifolds. We generalize this result to cases where $N$ may be noncompact, under assumptions on the way it is embedded into $M$. This results in an equality between two classes in the $K$-theory of the Roe algebra of $N$. Bunke and Ludewig, and Engel and Wulff, have recently obtained related results based on different approaches.
format Preprint
id arxiv_https___arxiv_org_abs_2507_16591
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A partitioned manifold index theorem for noncompact hypersurfaces
Hochs, Peter
de Kok, Thijs
Differential Geometry
K-Theory and Homology
Operator Algebras
Roe's partitioned manifold index theorem applies when a complete Riemannian manifold $M$ is cut into two pieces along a compact hypersurface $N$. It states that a version of the index of a Dirac operator on $M$ localized to $N$ equals the index of the corresponding Dirac operator on $N$. This yields obstructions to positive scalar curvature, and implies cobordism invariance of the index of Dirac operators on compact manifolds. We generalize this result to cases where $N$ may be noncompact, under assumptions on the way it is embedded into $M$. This results in an equality between two classes in the $K$-theory of the Roe algebra of $N$. Bunke and Ludewig, and Engel and Wulff, have recently obtained related results based on different approaches.
title A partitioned manifold index theorem for noncompact hypersurfaces
topic Differential Geometry
K-Theory and Homology
Operator Algebras
url https://arxiv.org/abs/2507.16591