Columbia Undergraduate Math Society

Spring 2024 <<  Summer 2024 Learning Seminar >> Fall 2024

Day and Time: Mondays, 5pm, on Zoom
Recordings are posted here. Topic: Representation Theory
Reference: Representations and Characters of Groups Contact UMS (Email Lisa Faulkner Valiente)
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Date Speaker Title Abstract
July 15
UMS Officers
Introduction
We will first introduce Summer UMS and then decide on the logistics for the next weeks. We will go over some potential textbooks we could cover and then pick one by vote. Every member will then have the opportunity to sign up to give a talk.
July 22
Lisa Faulkner Valiente
Review of Linear Algebra and Group Theory We review key definitions and results in linear algebra and group theory that will be relevant when studying representation theory, including eigenvalues and eigenvectors, the definition of a module, normal subgroups and quotient groups, and the first isomorphism theorem. If time permits, we will also give a precise definition of a representation of a group, and an example.
July 29
Yiming Song
Properties of Representations
 
We go over some fundamentals of linear algebra before introducing the notion of representations, their basic properties, equivalent representations, kernels, and faithfulness. Then we introduce FG-modules, a concept closely related to representations which will be useful for further study.
August 5th
Joseph McGill
FG-Modules, Irreducibility, and Regular Representations
After learning about FG modules last week, we want to explore their structure more in depth. This week we will discuss the idea of reducibility, along with specific useful modules such as the permutation modules. Finally we will tie these all together and discuss the group algebra, which gives way to the regular representation.
August 12
Maschke's Theorem, Schur's Lemma
Zachary Lihn
We'll continue our study of FG-modules by quickly defining FG-module homomorphisms and their basic properties. We'll then discuss the important result known as Maschke's Theorem, which reduces our study of FG-modules to the irreducible ones. Finally, we'll prove Schur's Lemma, which (time permitting) will allow us to classify the representations of finite abelian groups over the complex numbers.  
August 19
Characters, Orthogonality, and Some Physics
Andrew Navruzyan  
We introduce and prove fundamental facts about characters and their orthogonality for groups, highlighting the general story on Lie groups. We also introduce Weyl's unitary trick in addition to giving connections of representation theory to general relativity and quantum mechanics. TBD
August 26
TBD
TBD
 

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