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arXiv · 1503.06916

Indefinite Kasparov modules and pseudo-Riemannian manifolds

Koen van den Dungen·Adam Rennie
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Abstract

We present a definition of indefinite Kasparov modules, a generalisation of unbounded Kasparov modules modelling non-symmetric and non-elliptic (e.g. hyperbolic) operators. Our main theorem shows that to each indefinite Kasparov module we can associate a pair of (genuine) Kasparov modules, and that this process is reversible. We present three examples of our framework: the Dirac operator on a pseudo-Riemannian spin manifold (i.e. a manifold with an indefinite metric), the harmonic oscillator, and the construction via the Kasparov product of an indefinite spectral triple from a family of spectral triples. This last construction corresponds to a foliation of a globally hyperbolic spacetime by spacelike hypersurfaces.

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Koen van den Dungen, Adam Rennie. 2016-02-13. Indefinite Kasparov modules and pseudo-Riemannian manifolds. https://doi.org/10.1007/s00023-016-0463-z

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