Seminars Sorted by Series

Members' Colloquium

Nov
04
2024

Members' Colloquium

Zeroes of Characters (cf. J.-P. Serre, same title, arXiv 2312.17551)
1:00pm|Simonyi 101 and Remote Access

A promenade in Serre's paper, plus some related results of mine.

Nov
11
2024

Members' Colloquium

"Local-to-global" Theorems On High Dimensional Expanders
1:00pm|Simonyi 101 and Remote Access

Expansion in graphs is a well studied topic, with a wealth of applications in many areas of mathematics and the theory of computation.

High dimensional expansion is a generalization of expansion from graphs to higher dimensional objects, such as...

Nov
25
2024

Members' Colloquium

Challenges and Breakthroughs in the Mathematics of Plasmas
1:00pm|Simonyi 101 and Remote Access

This colloquium will explore some fundamental issues in the mathematics of plasmas, focusing on the stability and instability of solutions to Vlasov-type equations, which are crucial for describing the behavior of charged particles in a plasma. A...

Dec
02
2024

Members' Colloquium

Relationships Between Nilpotency and Curvature
1:00pm|Simonyi 101 and Remote Access

We travel the years in order to understand the relationship between Nilpotency and Riemannian geometry: including Gromov's almost flat theorem for manifolds with bounded curvature and Fukaya-Yamaguchi's almost nilpotency of spaces with lower...

Dec
09
2024

Members' Colloquium

Poisson Boundary, Liouville Property and Asymptotic Geometry of Linear Groups
1:00pm|Simonyi 101 and Remote Access

The Poisson-Furstenberg boundary  is a measure space that describes asymptotics of infinite trajectories of random walks. The boundary is non-trivial if and only if the defining  measure admits non-constant bounded harmonic functions. 

The origin of...

Jan
27
2025

Members' Colloquium

Around the Alexandrov-Fenchel Inequality
1:00pm|Simonyi 101 and Remote Access

In the late 1800s, in the course of his study of classical problems of number theory, the young Hermann Minkowski discovered the importance of a new kind of geometric object that we now call a convex set. He soon developed a rich theory for...

Feb
10
2025

Members' Colloquium

Quantitative Stability of Geometric Inequalities: Pr\'ekopa-Leindler and Borell-Brascamp-Lieb
1:00pm|Simonyi 101 and Remote Access

The Prékopa-Leindler inequality (PL) and its strengthening, the Borell-Brascamp-Lieb inequality, are functional extensions of the Brunn-Minkowski inequality from convex geometry, which itself refines the classical isoperimetric inequality. These...

Feb
24
2025

Members' Colloquium

Inequalities For Trees and Matroids
1:00pm|Simonyi 101 and Remote Access

In their 1971 study of telephone switching circuitry, Graham and Pollak designed a novel addressing scheme that was better suited for the faster communication required by computers. They introduced the distance matrix of a graph, and used its...

Mar
10
2025

Members' Colloquium

Erd\H{o}s Unit Distance Problem and Graph Rigidity
1:00pm|Simonyi 101 and Remote Access

Erd\H{o}s unit distance problem asks the following: Let $P$ be a set of $n$ distinct points in the plane, and let $U(P)$ denote the number of pairs of points in $P$ that are at distance 1. How large can $U(P)$ be? In 1946, Erd\H{o}s showed that for...

Members’ Seminar

Dec
06
2004

Members’ Seminar

Completing the Bernstein Program (A Geometric Conjecture within the Representation Theory of p-adic Groups)
4:00pm|S-101
Jan
31
2005

Members’ Seminar

Approximation algorithms and Grothendieck type inequalities
4:00pm|S-101

I will describe a connection between a classical inequality of Grothendieck and approximation algorithms based on semi-definite programming. The investigation of this connection suggests the definition of a new graph parameter, called the...

Feb
14
2005

Members’ Seminar

Blow up in a 3-D "toy" model for the Euler equations
4:00pm|S-101

We present a 3-D vector dyadic model given in terms of an infinite system of nonlinearly coupled ODE. This toy model is inspired by approximations to the fluid equations studied by Dinaburg and Sinai. The model has structural similarities with the...

Feb
22
2005

Members’ Seminar

A New Characterization of Sobolev Spaces
3:00pm|S-101

This talk is motivated by some recent work of Bourgain- rezis-Mironescu. A few years ago, they introduced an elementary way of defining the Sobolev spaces $W^{1,p}$ without making any use of derivatives. I will present their definition and some...

Mar
14
2005

Members’ Seminar

A Liouville Type Result for some Conformally Invariant Fully Nonlinear Equations
4:00pm|S-101

I will talk about some joint work with Yanyan Li which extended the Liouville type theorem of Caffarelli-Gidas-Spruck's on the Yamabe equation to the fully nonlinear case.

Mar
21
2005

Members’ Seminar

Polynomiality Properties of Type A Weight and Tensor Product Multiplicities
4:00pm|S-101

Kostka numbers and Littlewood-Richardson coefficients appear in the representation theory of complex semisimple Lie algebras of type A, respectively as the multiplicities of weights in irreducible representations, and the multiplicities of...

Mar
28
2005

Members’ Seminar

Exotic Smooth Structures on Rational Surfaces
4:00pm|S-101

Most known smoothable simply connected 4--manifolds admit infinitely many different smooth structures (distinguished, for example, by Seiberg--Witten invariants). There are some 4--manifolds, though, for which the existence of such 'exotic'...

Apr
11
2005

Members’ Seminar

Iterated Integrals and Algebraic Cycles
4:00pm|S-101

It will be on some constructions in the candidate category of mixed Tate Motives constructed by Bloch and Kriz.

Oct
31
2005

Members’ Seminar

Motivic Integration, Constructible Functions, and Stringy Chern Classes
4:00pm|S-101

In this talk I will discuss a joint work with Lupercio, Nevins and Uribe, in which we use motivic integration to give a theory of Chern classes for singular algebraic varieties that is birationally well-behaved (i.e., with a "stringy" flavor). The...

Nov
07
2005

Members’ Seminar

On some Properties of the Nottingham Group
4:00pm|S-101

Let F be a finite field. The Nottingham group N(F) is the group of formal power series \{ t(1+a_1 t + a_2 t^2 + ...): a_i \in F \}or, equivalently, the group of wild automorohisms of the local field F((t)). In spite of such a simple definition, the...

Nov
28
2005

Members’ Seminar

Generalized Teichmueller Spaces
4:00pm|S-101

Classical Teichmueller space parametrizes complex structures on a Riemann surface of genus g>1. Recently several generalized Teichmueller spaces have been defined and studied by very different approaches. Nevertheless, some of the results are...

Jan
30
2006

Members’ Seminar

Universality for Mathematical and Physical Systems
Percy Deift
4:00pm|S-101

All physical systems in equilibrium obey the laws of thermodynamics. In other words, whatever the precise nature of the interaction between the atoms and molecules at the microscopic level, at the macroscopic level, physical systems exhibit...

Feb
13
2006

Members’ Seminar

Random Walks and Equidistribution on Lie Groups
4:00pm|S-101

I will discuss various issues related to the local problem on Lie groups, the asymptotics of the return probablity, and the equidistribution of dense subgroups.

Feb
20
2006

Members’ Seminar

The Deligne-Simpson Problem and Double Affine Hecke Algebras
4:00pm|S-101

Let us fix $m$ conjugacy classes $C_1,\dots,C_m$ inside $GL(n)$. The variety of $m$-tuple of matrices such that: $$X_i\in C_i, \quad i=1,\dots,m mbox{ and } X_1\dots X_m=1.$$ is a solution of the Deligne-Simpson problem. Double affine Hecke algebras...

Mar
13
2006

Members’ Seminar

Multivariable Mahler Measure and Regulators
4:00pm|S-101

The Mahler measure of an n-variable polynomial P is the integral of log|P| over the n-dimensional unit torus T^n with the Haar measure. For one-variable polynomials, this is a natural quantity that appears in different problems such as Lehmer's...

Mar
27
2006

Members’ Seminar

Counting Polynomial Configurations on Dense Subsets of the Integers
4:00pm|S-101

The polynomial Szemeredi theorem of Bergelson and Leibman states that every integer subset with positive density contains infinitely many configurations of the form x,x+p_1(n),...x+p_k(n), where p_1,...,p_k is any fixed family of integer polynomials...

Apr
03
2006

Members’ Seminar

Generation of Finite Simple Groups and Derangements
4:00pm|S-101

We will first discuss some results on generation of finite simple groups. Using the classification of finite simple grouops, one can prove the following results: Every finite simple can be generated by two elements and the probability that a pair of...

Apr
10
2006

Members’ Seminar

String Topology and Closed Geodesics
4:00pm|S-101

Expository talk on work in progress. M.Chas and D.Sullivan introduced a product on the homology of the free loop spaace of a compact, oriented manifold M that has also been studied by R.L.Cohen, V.Godin, J.D.S.Jones, J.Klein, and others. If M is...

Apr
17
2006

Members’ Seminar

Fake Projective Spaces
4:00pm|S-101

A fake projective space is a smooth complex projective algebraic variety which is uniformized by the unit ball in $\mathbb C^n$ and whose Betti numbers are the same as that of $\mathbb P^n_{\mathbb{C}}$. The first example of a fake projective plane...

Apr
24
2006

Members’ Seminar

Some Results on Complete Symmetric Varieties
4:00pm|S-101

Let G be a semisimple adjoint group. There is a partition of its wonderful compactification into finitely many G-stable pieces, which was introduced by Lusztig. Each piece is a locally trivial fibration over a partial flag variety with fibres...

Oct
02
2006

Members’ Seminar

On the p-Adic Spectra of Some Hecke Operators
4:00pm|S-101

I'll first summarize my conjecture about the p-adic slopes of modular forms for GL_2 (both classical and overconvergent). This conjecture is based upon some structures in the geometry of the special fibers of elliptic modular curves at p. In an...

Oct
23
2006

Members’ Seminar

Open Gromov-Witten Theory of the Quintic Threefold
4:00pm|S-101

Recently, I defined an open Gromov-Witten invariant for Lagrangian submanifolds that arise as the real points of a real symplectic manifold. In this talk, I will discuss a calculation of the genus zero open Gromov-Witten theory of the Fermat type...

Nov
06
2006

Members’ Seminar

Equidistribution Problems on Siegel Modular Varieties
4:00pm|S-101

In this talk, I'd like to discuss an intriguing equidistribution property of automorphic forms on arithmetic quotients of homogeneous varieties, focusing on cuspidal Hecke eigenforms for Sp(n, Z), the Siegel modular group of genus n. Our approach is...

Nov
13
2006

Members’ Seminar

Random Geometry and SLE
4:00pm|S-101

We introduce and construct the "AC geometry" from the Gaussian free field and use it to prove various facts about Schramm-Loewner evolutions. 

Nov
15
2006

Members’ Seminar

Random Geometry and SLE II
2:30pm|S-101

We introduce and construct the "AC geometry" from the Gaussian free field and use it to prove various facts about Schramm-Loewner evolutions.