K-theory as a tool for classification of crystalline topological insulators

Topological K-theory provides a great tool to study topological phases in systems of free fermions. We start by reviewing an argument by Freed & Moore on the appearance of the K-theory of tori in the context of quantum mechanics. After the mathematical essence has been extracted, the focus will be on computational methods using the Atiyah-Hirzebruch spectral sequences. We will focus on the example of a 2-dimensional system with a rotational symmetry of order two.