Tian An Wong (UBC)

Abstract: In this talk, I will outline the basic ideas in Langlands’ Beyond Endoscopy proposal, and the role of summation formulas and the nontempered automorphic spectrum. I will discuss the various approaches of Frenkel-Langlands-Ngô, Altug, and Ngô to the geometric side of the trace formula, and propose an alternate approach beginning on the spectral side instead.

Location: MS 337 + https://zoom.us/j/171589529

Venue: Representation Theory Seminar at University of Alberta

https://sites.ualberta.ca/~kkoziol/sem/NTRT.html

Title: The geometry of Arthur packets

Abstract: This talk uses two examples to show how Arthur parameters determine a category of equivariant perverse sheaves and how the microlocal perspective on this category reveals the Arthur packet attached to the Arthur parameter. The full picture is explained in Arthur packets for p-adic groups by way of microlocal vanishing cycles, with examples, joint with Andrew Fiori, Ahmed Moussaoui, James Mracek and Bin Xu, to appear in Memoirs of the American Mathematical Society. The talk includes some remarks on an emerging categorical local Langlands correspondence.

On the compactification of mini-Vogan varieties V and the restriction functor D_P(G/P) --> D_H(V).

Clifton and Qing in Calgary, Geo in Radboud and Andrew in Lethbridge

Location: Zoom

Speakers: James Steele and André de Waal

We continue our study of the quiver category A_n and the four functors

J^* : A_n --> A_0,
J_* : A_0 --> A_n,
J_! : A_0 --> A_n and
J_{!*} : A_0 --> A_n.

The goal of the talk is to prove Propositions 3.3, 3.5 and 3.6 of Section 3.2 of Tom Braden's thesis.

Speaker: Qing Zhang

Qing and Clifton have now computed all ABV-packets for all unipotent Arthur parameters of the exceptional group G(2). The results are summarized in this talk.

Speaker: Geoff Vooys

In this talk we will introduce the Bernstein Decomposition and describe the Bernstein Centre of the category of smooth representations of the F-rational points of a p-adic group G. We will then describe how to realize the Bernstein Centre as a ring of sections of a variety, and, time permitting, use this to explain the parametrization of the Bernstein Decomposition.

Nicole will update us on her progress toward calculating the microlocal vanishing cycles of the Kashiwara-Saito singularity.

Clifton will make a small correction to the geometric multiplicity matrix for the admissible representations of G(2) with “subregular unipotent” infinitesimal parameter.
Qing will explain that he’s found all the admissible representations and standard modules of G(2) with “subregular unipotent” infinitesimal parameter and that the multiplicity matrix matches the geometric calculation. This concludes the proof of the Kazhdan-Lusztig conjecture (as it appears in the Voganish book) for the subregular unipotent infinitesimal parameter of G(2).