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arXiv · 1507.03689

Zappa-Szép product groupoids and C*-blends

Nathan Brownlowe·David Pask·Jacqui Ramagge·David Robertson·Michael F. Whittaker
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Abstract

We study the external and internal Zappa-Szép product of topological groupoids. We show that under natural continuity assumptions the Zappa-Szép product groupoid is étale if and only if the individual groupoids are étale. In our main result we show that the C*-algebra of a locally compact Hausdorff étale Zappa-Szép product groupoid is a C*-blend, in the sense of Exel, of the individual groupoid C*-algebras. We finish with some examples, including groupoids built from *-commuting endomorphisms, and skew product groupoids.

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Nathan Brownlowe, David Pask, Jacqui Ramagge, David Robertson, Michael F. Whittaker. 2017-06-14. Zappa-Szép product groupoids and C*-blends. https://doi.org/10.1007/s00233-016-9775-z

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