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SUMMARY:Principal groupoid models for the Cuntz algebras - Samuel  Evingto
 n (Westfalische Wilhelms-Universitat Munster)
DTSTART:20250717T092500Z
DTEND:20250717T094500Z
UID:TALK233101@talks.cam.ac.uk
DESCRIPTION:I will begin with a brief discussion of Renault's classical co
 nstruction of a groupoid that gives rise to the Cuntz algebra O_n with its
  canonical Cartan subalgebra. Renault's groupoid model has isotropy (i.e. 
 the dynamics has some fixed points). This means that the canonical Cartan 
 in O_n isn't a C*-diagonal\, and in particular has infinite diagonal dimen
 sion.\n&nbsp\;\nIn the second half of the talk\, I will outline my recent 
 work with Philipp Sibbel on constructing a groupoid model for the Cuntz al
 gebra O_n with no isotropy (i.e. a principal groupoid). This groupoid give
 s rise to a C*-diagonal inside of O_n whose spectrum is a Cantor space.\n&
 nbsp\;\nThe groupoid can be realised as a product of the Deaconu-Renault g
 roupoid associated to a well-chosen topological graph with the groupoid of
  a well-chosen AF equivalence relation.
LOCATION:External
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