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KK-Theory and Spectral Flow in von Neumann Algebras

Published online by Cambridge University Press:  04 April 2012

J. Kaad
Affiliation:
Institute for Mathematical Sciences, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark, [email protected]
R. Nest
Affiliation:
Institute for Mathematical Sciences, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark, [email protected]
A. Rennie
Affiliation:
Mathematical Sciences Institute, John Dedman Building, Australian National University, Acton 0200, ACT, Australia, [email protected]
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Abstract

We present a definition of spectral flow for any norm closed ideal J in any von Neumann algebra N. Given a path of selfadjoint operators in N which are invertible in N/J, the spectral flow produces a class in Ko(J).

Given a semifinite spectral triple (A, H, D) relative to (N, τ) with A separable, we construct a class [D] ∈ KK1(A, K(N)). For a unitary uA, the von Neumann spectral flow between D and u*Du is equal to the Kasparov product [u]A[D], and is simply related to the numerical spectral flow, and a refined C*-spectral flow.

Type
Research Article
Copyright
Copyright © ISOPP 2012

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