On the Unbounded Picture of -Theory

In the founding paper on unbounded -theory, it was established by Baaj and Julg that the bounded transform, which associates a class in -theory to any unbounded Kasparov module, is a surjective homomorphism (under a separability assumption). In this paper, we provide an equivalence relation on unbou...

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Published in:Symmetry, Integrability and Geometry: Methods and Applications
Date:2020
Main Author: Kaad, Jens
Format: Article
Language:English
Published: Інститут математики НАН України 2020
Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/210766
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Journal Title:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Cite this:On the Unbounded Picture of -Theory. Jens Kaad. SIGMA 16 (2020), 082, 21 pages

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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Summary:In the founding paper on unbounded -theory, it was established by Baaj and Julg that the bounded transform, which associates a class in -theory to any unbounded Kasparov module, is a surjective homomorphism (under a separability assumption). In this paper, we provide an equivalence relation on unbounded Kasparov modules, and we thereby describe the kernel of the bounded transform. This allows us to introduce a notion of topological unbounded -theory, which becomes isomorphic to -theory via the bounded transform. The equivalence relation is formulated entirely at the level of unbounded Kasparov modules and consists of homotopies together with an extra degeneracy condition. Our degenerate unbounded Kasparov modules are called spectrally decomposable since they admit a decomposition into a part with positive spectrum and a part with negative spectrum.
ISSN:1815-0659