MATHUN3951_001_2025_3 Undergraduate Seminar (Fall 2025) -- Diagrammatic Algebra

Much of the advances of representation theory in the 21st century has come from diagrammatic algebra. Though there are often deep ties with very sophisticated geometry, diagrammatic algebra has the benefit of being computationally amenable (depending on your standards) and, as the name suggests, very pictorial. For example, one key diagrammatic innovation this century was the advent of `diagrammatic Soergel calculus', which gives a `categorification' of the `Hecke algebra'. In this course, we will (attempt to) follow the book ``Diagrammatic Algebra'' by Chris Bowman to steal a glimpse into this world.

Students are expected to be familiar with linear algebra, as well as group theory and Modern Algebra I. Some representation theory of finite groups would be helpful.

Each week two students will give talks, 55-60 minutes each. I will assign sections in advance. We will take a short break in between if we decide to do both talks the same day. Students are expected to attend and follow all talks. There will be ``exercises'' each week -- the speakers will each design one exercise, the students will each come up with an exercise themselves, and I will also assign an exercise, for a total of 3. What ``exercise'' here means is nebulous and up to interpretation (probably most often an example computation in a small case). Students may have to give multiple talks throughout the semester, depending on enrollment.

Schedule

09/10
Speaker: Fan Zhou
Title: Intro
Abstract: I will give a motivating example and set the stage for the class. I will also maybe cover some algebraic background for those who need it.
09/17
Speaker: Fanglin Yuan
Title: Symmetries
Abstract: Chapter 1.
09/24
Speaker: Max MikoLevine
Title: Coxeter groups
Abstract: Most of Chapter 2.
09/24
Speaker: Aryaman Rakhecha
Title: Group theory
Abstract: Most of Chapter 3.
10/01
Speaker: Hellen Zhao
Title: Introduction to algebras and Temperley-Lieb
Abstract: Sections 5.1-5.3.
10/08
Speaker: Aryaman Rakhecha
Title: Gradings, zig-zags, and oriented Temperley-Lieb
Abstract: Sections 5.4-5.5.
10/08
Speaker: Aisha Tabassum
Title: Binary Schur
Abstract: Sections 5.6-5.7.

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