Twisted equivariant K-theory

This talk continues the theme of last week. The objective is to give a gentle introduction to twisted equivariant K-theory, following Freed-Moore paper. This will work as a lead to the forthcoming lecture, where the special case of time-reversal symmetry for topological insulators will be discussed. In  particular, the Kane-Mele invariant that identifies topological insulators will be realised as a class in Real K-theory of the Brillouin torus.