K-Theory of C*-Algebras

Lecturer: Prof. Dr. Moritz Weber
Assistant: Luca Junk


Monday, 14-16 in seminar room 10, building E2 4

Exercise Sessions

every second Thursday, 12-14 in seminar room 10, building E2 4 (starting from 27.04.)


In this lecture, we will introduce K-theory for C*-algebras. This is a theory of invariants for C*-algebras
with a homological flavour. More concretely, to any C*-algebra A we assign an abelian group K0(A)
which somehow "counts the projections", as well as an abelian group K1(A) which somehow "count
s the unitaries". Almost more important than the definition of the K-groups are the homological
properties of the K functor: it preserves many natural constructions making it much simpler to
compute the K-groups in concrete cases.

See also winter term 2019/2020 for a previous variant of this lecture.

Participants should know the definition and some basics on C*-algebras as well as functional analysis.


  • Rordam, Mikael; Larsen, Flemming; Laustsen, Niels, An introduction to K-theory for C*-algebras, 2000.
  • Blackadar, Bruce, K-theory for operator algebras, 1998.
  • Wegge-Olsen, Niels, K-theory and C*-algebras. A friendly approach, 1993.
  • Blackadar, Bruce, Operator algebras. Theory of C*-algebras and von Neumann algebras, 2006.
  • Brown, Nathanial; Ozawa, Narutaka, C*-algebras and finite-dimensional approximations, 2008.
  • Davidson, Kenneth, C*-algebras by example, 1996.
  • Lecture notes by Christian Voigt

You can find these references in the library.

Postal address

Saarland University
Department of Mathematics
Postfach 15 11 50
66041 Saarbrücken

Physical address

Saarland University
Campus building E 2 4
66123 Saarbrücken