#### Room 326

#### Groupoids associated to Semigroup actions (Revolutions)

#### S. Sundar

##### CMI

*Let $P$ be a solid closed convex cone in \mathbb{R}^{n}. The Weiner Hopf algebra associated to P is the cut-down of the group C*-algebra to L^{2}(P). The work of Muhly and Renault describes the structure of Weiner Hopf algebra in terms of groupoids. In my talk, I will explain how semigroup actions give rise to groupoids and its significance to the above example. This is joint work with Jean Renault. Third and final part.*

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