Groupoids and Noncommutative Geometry Seminar 

13/12/2007, 13:30 — 14:30 — Room P3.10, Mathematics Building
Rogier Bos, CAMGSD

Topological approaches to groupoid cohomology, part 2

In this lecture we focus on cohomology of etale groupoids (without smoothness assumptions) and sheaves on these etale groupoids (not representations as before). We give a minimal(/crash) introduction to simplicial objects and geometric realization and apply this to categories and groupoids. Next we make the link to the first series of lectures in this series by explaning the relation to semigroup cohomology (following Renault). If time allows, we also discuss a related approach by Moerdijk using the so-called embedding category of a groupoid.