1 Department of Mathematical Sciences, Faculty of Science, Københavns Universitet2 Mathematical Sciences Institute, Australian National University, Australia3 Department of Mathematical Sciences, Faculty of Science, Københavns Universitet
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, t) with A separable, we construct a class [D] ¿ KK1 (A, K(N)). For a unitary u ¿ A, 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.
Journal of K-theory, 2012, Vol 10, Issue 2, p. 241-277