Presentation topics, Representation Theory, Math 9140a
Each student will give one presentation near the end of the course.
All presentations will be done using the blackboard.
All students are expected to attend all presentations and to arrive on time.
These are suggestions, but you can also propose other topics.
Topics need to be discussed with me and approved.
You should choose a topic that is not something you already know about.
When you meet with me, I can give more information about
the topics and can suggest further references.
You should also do some research about the topics.
Some of these may be covered in class, as the final choice of
course material is still being worked out.
Sternberg's book is available here.
- The representation ring of a group, which organizes information about
direct sum and tensor product of representations.
The wikipedia page
gives some references, and sample computations.
Working out some of these computations could be part of the presentation.
See also Broecker-tom Dieck, Section II.7, which defines R(G) using class functions.
- Representations of semidirect products of groups.
3.8 in Sternberg is one possible source, but I believe there are slicker ways to do it.
See Section 8.2 of Serre's book on representation theory and/or
Section 3.7 of Andy
Baker's notes for brief treatments.
- The representations of the Poincare group, using the previous item.
This gives Wigner's classification of particles by mass and spin.
Sternberg does this in 3.9, but some parts aren't clear.
Other references are given in
book (Thm 9.4, 2nd ed.).
This article by Straumann
might be helpful.
There's also a long, inconclusive discussion at the
- Representations of Sn (Steinberg, Chapter 10). This is too
much for one presentation, but it could be split into two, with
one focusing on the combinatorics of Young diagrams/tableaux/tabloids
and the other on the representation theory. Even then, there would
only be time for highlights.
Chapter 7 of the book Diaconis, 1988
is probably an even better source than Steinberg, as it is more efficient.
Many other sources cover this material as well.
- An application of Fourier analysis to graph theory, as in
Section 5.4 of Steinberg. Remark 5.4.13 contains pointers to
further work, which might be good to incorporate.
Mohabat is doing this.
- Voting and Fourier analysis on the symmetric group Sn,
e.g. via the references mentioned in Example 5.5.8 of Steinberg
(e.g. Diaconis, 1989).
- Probability and random walks on groups (Steinberg, Chapter 11,
- The fast Fourier transform; most treatments don't have much
representation theory, so this is a bit tangential.
(One exception is a survey paper by D. Maslen and D. Rockmore
but it's fairly intricate.)
- Representations of SU(2) (e.g. Sternberg 4.3).
- Representations of compact topological groups or Lie groups,
possibly covering Haar measure and the Peter-Weyl theorem
(e.g. Sternberg 4.1, 4.2 and Appendix E; or J.F. Adams, Lectures
on Lie Groups; or Bump, Lie Groups; or Bröcker and tom Dieck, Representations of Compact Lie Groups; etc.)
- Representations of Lie algebras and su(2).
(Sternberg 4.10 and 4.11 is one possible source, but there are many others.)
- To what extent does the representation theory of a finite group G determine the group?
The answer depends on what you remember about the representations.
Tannaka duality provides one answer, and there are other interesting
things to discuss. Ask me for references.
- Group cohomology (e.g. Carlson's book,
Weibel's book on homological algebra,
article by Isaksen, etc.)
- Modular representation theory, i.e. representations over finite
fields; maybe also the stable module category of a group
(e.g. Carlson's book).
- Applications to particle physics (e.g. Sternberg 3.10, 3.12, 5.9 to 5.12, ...).
- Applications to crystalography (e.g. Sternberg 1.5, 1.8, 1.9, 1.10).
- Other applications (e.g Sternberg 4.5 to 4.9).
- Representations of quantum groups/Hopf algebras, or just SLq(2).
Connections between representation theory of quantum groups and knot theory.
- The Hurwitz Theorem about sums of squares, proved using representation theory.
This relates to the existence of division algebras over the reals.
notes by Keith Conrad.
The presentations are not long, so you will need to carefully
select the appropriate amount of material to present.
You should focus on the key ideas, with illustrative examples,
motivation, necessary background, and history (e.g. attributions and years).
You aren't expected to prove everything, but should give one or two
It should be regarded more like a seminar talk than a course lecture.
The presentations will be worth 1/3 of the overall mark in the course.
They will be graded on:
Note that knowledge of material is just a small part of the grade.
The presentation itself is much more important. Because of this, you
should practice the talk at least once or twice beforehand, on
a blackboard, with someone listening, and you should time how long
it takes. This is extremely important. You should also address
your presentation to your fellow students, not to me; students in the audience
are strongly encouraged to ask questions during and after the talk.
- Outline and draft: Well-organized; appropriate choice of
topics and amount of material; done on time.
- Knowledge of material. Be prepared to answer questions.
- Clarity and style of presentation: speaking clearly, looking
at audience, giving clear explanations, etc.
- Blackboard use: use boards in order, don't erase what you've
just written, don't stand in front of what you've written,
use coloured chalk when appropriate, use the side board for
things you want to leave up, etc.
- Duration: if you end within the time span given, you get full
marks for this category; otherwise, you lose marks. You might
want to build some flexibility into the end of your presentation
so you can adjust on the fly. And take into account that there
may be questions during your talk.
- May 21-May 25: look over topics and read about a couple of them.
- In class on May 29 we'll decide on topics and select dates.
Bring two possible choices of topic to class.
Talks will take place during the last two weeks of classes.
- Finalize choice of your topic ≥ 3 weeks ahead of your date.
- Give me a brief outline (1 to 2 pages) ≥ 2 weeks ahead of
- Give me a draft of the whole talk ≥ 1 week ahead of your date.
Indicate which parts you will say and which parts you will write on the board.
Course home page.