Difference between revisions of "Colloquia/Spring2020"
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Revision as of 17:24, 31 August 2019
All colloquia are on Fridays at 4:00 pm in Van Vleck B239, unless otherwise indicated.
|Sept 6||Will Sawin (Columbia)||On Chowla's Conjecture over F_q[T]||Marshall|
|Sept 13||Yan Soibelman (Kansas State)||Riemann-Hilbert correspondence and Fukaya categories||Caldararu|
|Sept 16 Monday Room 911||Alicia Dickenstein (Buenos Aires)||TBA||Craciun|
|Sept 20||Jianfeng Lu (Duke)||TBA||Qin|
|Sept 27||Omer Mermelstein (Madison)||Andrews|
|Oct 11||Shamgar Gurevich (Madison)||Harmonic Analysis on GL(n) over Finite Fields||Marshall|
|Nov 1||Elchanan Mossel (MIT)||Distinguished Lecture||Roch|
|Nov 8||Reserved for job talk|
|Nov 15||Reserved for job talk|
|Nov 22||Reserved for job talk|
|Dec 6||Reserved for job talk|
|Dec 11 Wednesday||Nick Higham (Manchester)||LAA lecture||Brualdi|
|Dec 13||Reserved for job talk|
|Jan 24||Reserved for job talk|
|Jan 31||Reserved for job talk|
|Feb 7||Reserved for job talk|
|Feb 14||Reserved for job talk|
|Feb 28||Brett Wick (Washington University, St. Louis)||Seeger|
|March 6||Jessica Fintzen (Michigan)||Marshall|
|March 20||Spring break|
|March 27||(Moduli Spaces Conference)||Boggess, Sankar|
|April 3||Caroline Turnage-Butterbaugh (Carleton College)||Marshall|
|April 10||Sarah Koch (Michigan)||Bruce (WIMAW)|
|April 24||Natasa Sesum (Rutgers University)||Angenent|
|May 1||Robert Lazarsfeld (Stony Brook)||Distinguished lecture||Erman|
Will Sawin (Columbia)
Title: On Chowla's Conjecture over F_q[T]
Abstract: The Mobius function in number theory is a sequences of 1s, -1s, and 0s, which is simple to define and closely related to the prime numbers. Its behavior seems highly random. Chowla's conjecture is one precise formalization of this randomness, and has seen recent work by Matomaki, Radziwill, Tao, and Teravainen making progress on it. In joint work with Mark Shusterman, we modify this conjecture by replacing the natural numbers parameterizing this sequence with polynomials over a finite field. Under mild conditions on the finite field, we are able to prove a strong form of this conjecture. The proof is based on taking a geometric perspective on the problem, and succeeds because we are able to simplify the geometry using a trick based on the strange properties of polynomial derivatives over finite fields.
Yan Soibelman (Kansas State)
Title: Riemann-Hilbert correspondence and Fukaya categories
Abstract: In this talk I am going to discuss the role of Fukaya categories in the Riemann-Hilbert correspondence for differential, q-difference and elliptic difference equations in dimension one. This approach not only gives a unified answer for several versions of the Riemann-Hilbert correspondence but also leads to a natural formulation of the non-abelian Hodge theory in dimension one. It also explains why periodic monopoles should appear as harmonic objects in this generalized non-abelian Hodge theory. All that is a part of the bigger project ``Holomorphic Floer theory", joint with Maxim Kontsevich.
Shamgar Gurevich (Madison)
Title: Harmonic Analysis on GL(n) over Finite Fields.
Abstract: There are many formulas that express interesting properties of a finite group G in terms of sums over its characters. For evaluating or estimating these sums, one of the most salient quantities to understand is the character ratio:
trace(ρ(g)) / dim(ρ),
for an irreducible representation ρ of G and an element g of G. For example, Diaconis and Shahshahani stated a formula of the mentioned type for analyzing certain random walks on G.
Recently, we discovered that for classical groups G over finite fields there is a natural invariant of representations that provides strong information on the character ratio. We call this invariant rank.
This talk will discuss the notion of rank for the group GLn over finite fields, demonstrate how it controls the character ratio, and explain how one can apply the results to verify mixing time and rate for certain random walks.
This is joint work with Roger Howe (Yale and Texas AM). The numerics for this work was carried by Steve Goldstein (Madison)