Character Theory of Finite Groups SS 2023


Lecture: Mondays 10:00 - 11:30 Room 48-538 Lecturer: Jun.-Prof. Dr. Caroline Lassueur
Exercises: Fridays 11:45 - 13:15 Room 48-438 Instructor: Annika Bartelt
Office hour: Upon request

Link to the live stream: From Week 2 on in OpenOLAT over BBB.

Public holidays / Exceptional schedule:
  • Friday, the 28th of April: the 1st Exercise Class is replaced by a lecture.
  • 1st of May 2023: Labour Day - no lecture
  • 29th of May 2023: Pentecost Monday - no lecture

Office hours: you can make appointments with me for individual qusetion sessions.

Exam Dates:
  • With U. Thiel: 31.07.2023
  • With A. Gathmann: 29.08.2023


  • April 2023: please register in the URM system by Friday, the 24th of April, midday.

Lecture Notes

I will essentially follow my \(LaTeX\)ed lecture notes from the SS 2022, up to small alterations.
You can use the version of the SS 2022 for Chapters 1 to 6.

In the SS 2023 I will add a Chapter 7 on Frobenius Groups, which will be treated in the last lectures. Here are the updated full \(LaTeX\)ed lecture notes of the SS 2023 including Chapter 7.

Here are the topics treated in the corresponding weeks (updated at the end of the lecture):


The Exercise Classes take place fortnightly. The Exercise Sheets will be uploaded below.

Friday, the 28th of April: the 1st Exercise Class is replaced by a lecture, in order to make up for the two public holidays during the 1st half of the semester. This way the exercises will let us cover the material seen in the lectures in a more consistent way.

Handing in solutions:
Please hand in your solution sheets on Wednesdays, at the latest at 6 pm in the dedicated letter-box next to Lecture Theater 208 or upload them in OpenOLAT.
  • You should hand in your solutions in handwritten form by the due date. No LaTeXed solutions accepted.
  • You can hand in in groups of up to two students.


You obtain an "Übungsschein" if the following criteria are fulfilled:
  • you have obtained at least 40% of the possible points on each exercise sheet;
    (handing-in in groups of two students is possible)
  • you have actively taken part to the exercise classes: attendance to the exercise classes + presenting at least two solutions on the board during the semester.


Textbooks you can use are the following. However, the lectures do not follow any of them faithfully.
  • [JL01] G. James and M. Liebeck, Representations and characters of groups. See [zbMATH].
  • [Ser77] J.-P. Serre, Linear representations of finite groups. See [zbMATH].
    The original text is:
    [Ser98] J.-P. Serre, Représentations linéaires des groupes finis. See [zbMATH].
  • ([Isa06] M. Isaacs, Character theory of finite groups. See [zbMATH].)
  • [Web16] P. Webb, A course in finite group representation theory. See [zbMATH].
  • [CCNPW85] J.H. Conway, R.T. Curtis, S.P. Norton, R. Parker, R.A. Wilson, Atlas of Finite Groups. Clarendon Press, Oxford, 1985.
As a complement to my lecture notes, I strongly recommend Peter Webb's book, whose pre-print version is available at his webpage.

Oral Exam

In principle one should be able to explain the content of the lecture. Warning: this semester I have added a Chapter 7 about Frobenius groups to the lecture notes.
  • Definitions, statements of the theorems/propositions/lemmata should be known.
  • You should be able to explain short proofs as well as the main arguments of the longer proofs.
  • The Exercises mentioned in the lecture are important for the understanding of the theory.
  • There won't be any direct questions on the content of the Appendices.
  • You should also be able to give concrete examples/counter-examples to illustrate the results.
  • There will also be questions on concrete examples.
  • Also be ready to write down formally the concepts and results you are explaining.

A typical exam question would be as follows: Explain all entries in the character table on the cover page picture and find the missing entries. (Several methods possible!)


Annika Bartelt : exercise classes / organisation
Marie Roth : exercise marking / organisation

Contents of the Lecture

  • Linear representations and characters
  • Modules over the group algebra
  • Character tables, orthogonality relations
  • Burnside's \(p^aq^b\)-theorem
  • Restriction, induction, inflation, tensor products
  • Clifford theory
  • Frobenius groups

Prerequisites: elementary group theory and linear algebra


Lecture : 2 SWS, i.e. 30 contact hours
Exercises : 1 SWS, i.e. 15 contact hours

Further Documents

Introduction Slides