Introduction to K-theory (K-Theory)

Course content

K-theory associates to a C*-algebra A two abelian groups K_0(A) and K_1(A) that on the one hand contain deep information about the algebra A and on the other hand can be calculated for great many algebras. K-theory is one of the most important constructions in operator algebras, non-commutative geometry and in topology with a host of applications in mathematics and in physics. For commutative unital C*-algebras, alias continuous functions on compact spaces, there are two equivalent descriptions of the K-groups, each with its own advantages. In one description K_0 classifies (stable) projections and in the other description it classifies (stable) vector bundles over the compact space(the spectrum) associated to the algebra.

The course will contain the following specific elements:

  • Projections and unitaries in C*-algebras
  • The Grothendieck construction af K-theory
  • Classification of AF-algebras
  • Exact sequences and calculation of K-groups.
  • Bott periodicity.
  • The six term exact sequence in K-theory.



MSc Programme in Mathematics

Learning outcome

Knowledge: The student will obtain knowledge of the elements mentioned in the description of the content

Skills: After completing the course the student will be able to
1. calculate K-groups
2. classify projections and unitaries in C*-algebras
3. understand AF-algebras and their classification

After completing the course the student will be able to
1. prove theorems within the subject of the course
2. apply the theory to concrete C*-algebras
3. understand the extensive litterature on elementary K-theory and to read the more advanced parts of the subject.

4 hours of lectures and 3 hours of exercises per week for 8 weeks.

Functional Analysis (FunkAn) and Introduction to Operator Algebra (IntroOpAlg)

7,5 ECTS
Type of assessment
Continuous assessment
Evaluation during the course of 6 written assignments. Each assignment counts equally towards the grade.
All aids allowed
Marking scale
7-point grading scale
Censorship form
No external censorship
One internal examiner.
Criteria for exam assessment

The student must in a satisfactory way demonstrate that he/she has mastered the learning outcome of the course.

Single subject courses (day)

  • Category
  • Hours
  • Lectures
  • 32
  • Theory exercises
  • 24
  • Preparation
  • 150
  • English
  • 206