Article ID Journal Published Year Pages File Type
4657733 Topology 2006 17 Pages PDF
Abstract

It is well known that the signature operator on a manifold defines a KK-homology class which is an orientation after inverting 2. Here we address the following puzzle: What is this class localized at 2, and what special properties does it have? Our answers include the following:•the KK-homology class ΔMΔM of the signature operator is a bordism invariant;•the reduction mod 8 of the KK-homology class of the signature operator is an oriented homotopy invariant;•the reduction mod 16 of the KK-homology class of the signature operator is not an oriented homotopy invariant.

Related Topics
Physical Sciences and Engineering Mathematics Geometry and Topology
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