### Abstract

We define a new homology theory defined on discrete rings with involution (even when 2 is not invertible). This theory sastisfies excision, homotopy invariance, periodicity (of period 4) and other nice properties. It is closely related to Balmer's theory and to surgery groups. When A is a real or complex C*-algebra, we recover topological K-theory (up to 2-torsion).

### Related Links

- http://www.math.jussieu.fr/~karoubi/ - Web page of Max Karoubi