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Poincaré self-duality of A_θ

The irrational rotation algebra A_θ is known to be Poincaré self-dual in the KK-theoretic sense. The spectral triple representing the required K-homology fundamental class was constructed by Connes out of the Dolbeault operator on the 2-torus, but
so far, there has not been an explicit description of the dual element. We geometrically construct, for certain elements g of the modular group, a finitely generated
projective module L_g over A_θ ⊗ A_θ out of a pair of transverse Kronecker flows on
the 2-torus. For upper triangular g, we find an unbounded cycle representing the
dual of said module under Kasparov product with Connes' class, and prove that this
cycle is invertible in KK(A_θ,A_θ), allowing us to 'untwist' L_g to an unbounded cycle
representing the unit for the self-duality of A_θ. / Graduate

Identiferoai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/11678
Date09 April 2020
CreatorsDuwenig, Anna
ContributorsEmerson, Heath, Laca, Marcelo
Source SetsUniversity of Victoria
LanguageEnglish, English
Detected LanguageEnglish
TypeThesis
Formatapplication/pdf
RightsAvailable to the World Wide Web

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