Summary: LECTURES ON ORBIFOLDS AND GROUP COHOMOLOGY
ALEJANDRO ADEM AND MICHELE KLAUS
Abstract. The topics discussed in these notes include basic properties and definitions
of orbifolds, and aspects of their cohomology and K­theory. Connections to group coho-
mology and equivariant algebraic topology appear in the context of orbifolds and their
associated invariants. These notes are based on lectures given by the first author at the
summer school on Orbifolds and Transformation Groups, held at Hangzhou China in
June/July 2008.
Contents
1. Introduction 1
2. Classical orbifolds 2
3. Examples of Orbifolds 4
4. Orbifolds and manifolds 5
5. Orbifolds and groupoids 6
6. The Orbifold Euler Characteristic and K­theory 12
7. Stringy Products in K­theory 15
8. Twisted version 18
References 21
1. Introduction
Orbifolds and their invariants play an important role in mathematics. The study of basic

Source: Adem, Alejandro - Department of Mathematics, University of British Columbia

Collections: Mathematics