The Dixmier-Douady classes of certain groupoid C∗-algebras with continuous trace

  title={The Dixmier-Douady classes of certain groupoid C∗-algebras with continuous trace},
  author={Marius Ionescu and Alex Kumjian and Aidan Sims and Dana P. Williams},
  journal={Journal of Operator Theory},
Given a locally compact abelian group G, we give an explicit formula for the Dixmier-Douady invariant of the C∗-algebra of the groupoid extension associated to a Cech 2-cocycle in the sheaf of germs of continuous G-valued functions. We then exploit the blow-up construction for groupoids to extend this to some more general central extensions of etale equivalence relations. 
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