Previous Special Year Seminar

Nov
10
2020

SL2 Seminar

Blocks and Defect Groups of SLn
3:00pm|Remote Access

The modular representation theory of a finite group naturally breaks into different pieces called blocks, and the defect of a block is a sort of measure of its complexity. I will recall some basic aspects of this theory, and then give the complete...

Nov
04
2020

Geometric and Modular Representation Theory Seminar

The Derived Geometric Satake Equivalence of Bezrukavnikov and Finkelberg
3:00pm|Simonyi Hall 101 and Remote Access

This is the last talk towards understanding Bezrukavnikov-Finkelberg's derived geometric Satake equivalence. With the preparations from previous talks, we will introduce two filtrations: a topological filtration on the equivariant cohomology and an...

Nov
03
2020

SL2 Seminar

Decomposition numbers in defining characteristic
4:00pm|Remote Access

The decomposition of the reduction of a Deligne--Lusztig character as a sum of Weyl modules is given by Jantzen's formula. In the case of $SL_2(F_q)$ the formula can be proved by a direct computation, and as a result we will see that the entries in...

Oct
28
2020

Geometric and Modular Representation Theory Seminar

Derived Equivariant Cohomology of the affine Grassmannian and Bezrukavnikov and Finkelberg’s equivalences
3:00pm|Simonyi Hall 101 and Remote Access

This is the third talk in a series of three talks on the derived Satake equivalence. I will give an overview of the article of Bezrukavnikov and Finkelberg which explains how the equivariant derived category of the affine Grassmannian can be...

Oct
21
2020

Geometric and Modular Representation Theory Seminar

(Equivariant) Cohomology of the affine Grassmannian and Ginzburg’s picture
3:00pm|Simonyi Hall 101 and Remote Access

This is the second talk in a series of three talks on the derived Satake. I will give an overview of an article by Ginzburg which laid the foundational ideas for this equivalence.

Oct
20
2020

SL2 Seminar

Representations of GL_2(F_q) in defining characteristic: a number-theorist's perspective
Matthew Emerton
5:00pm|Remote Access

In this talk I hope to explain how the representation theory of $GL_n(F_q)$ (with q being a power of p) in char. p, and also in mixed characteristic $(0,p)$, plays an important role in the theory of Galois representations and the Langlands program...

Oct
14
2020

Geometric and Modular Representation Theory Seminar

An introduction to affine Grassmanians and the geometric Satake equivalence
3:00pm|Simonyi Hall 101 and Remote Access

This is the first talk in a series of three talks towards understanding Bezrukavnikov-Finkelberg's derived geometric Satake equivalence. In this talk, we recall the geometry of equal characteristic affine Grassmannians and some of the ingredients of...

Oct
07
2020

Geometric and Modular Representation Theory Seminar

Finite groups as algebraic groups in non-defining characteristic
3:00pm|Simonyi Hall 101 and Remote Access

We will discuss the conjecture of Broue relating modular representations of finite groups of Lie type in non-defining characteristic to those of normalizers of Levi subgroups, with a focus on $GL_n$. The categories of representations can be related...

Sep
30
2020

Geometric and Modular Representation Theory Seminar

Finite groups as algebraic groups in defining characteristic
3:00pm|Simonyi Hall 101 and Remote Access

We will discuss $p$-local representation theory and conjectures of Broue and Alperin, the latter been inspired by finite groups of Lie type in characteristic $p$. The issue is the extent to which the category of representations can be reconstructed...