Seminars Sorted by Series
Members’ Colloquium
Growth of cohomology in towers of manifolds: a topological application of the Langlands program
2:00pm|Simonyi Hall 101 and Remote Access
How does the dimension of the first cohomology grow in a tower
of covering spaces? After a tour of examples of behaviors for
low-dimensional spaces, I will focus on arithmetic manifolds.
Specifically, for towers of complex hyperbolic manifolds, I...
Mathematical foundations for human-level intelligence (Part 1): Cooperative communication as belief transport
2:00pm|Simonyi Hall 101 and Remote Access
Human learning outstrips modern machine learning and AI in at
least three abilities: rapid robust learning, in effectively open
worlds, in near-real time with very little energy. Mathematical
formalization of signature human abilities has the...
Fluid equations: regularity and Kolmogorov’s turbulence theory
2:00pm|Simonyi Hall 101 and Remote Access
The regularity theory for the Navier-Stokes equation will be
reviewed. Motivations from Kolmogorov’s phenomenological theory of
turbulence will be discussed. Rigorous mathematical results are
obtained to confirm some of the phenomenologies.
Old and New Results on the Spread of the Spectrum of a Graph
2:00pm|Simonyi Hall 101 and Remote Access
The spread of a matrix is defined as the diameter of its
spectrum. This quantity has been well-studied for general matrices
and has recently grown in popularity for the specific case of the
adjacency matrix of a graph. Most notably, Gregory...
A new random model for the Euler and Navier-Stokes equations and related equations
2:00pm|Simonyi Hall 101 and Remote Access
I will introduce a new model of randomly agitated equations. I
will focus on the finite finite dimensional approximations
(analogous to Galerkin approximations) and the two-dimensional
setting. I will discuss number of properties of the models...
2:00pm|Simonyi Hall 101 and Remote Access
No seminar: Dr. MLK Jr. Day
2:00pm|Simonyi Hall 101 and Remote Access
Cubic surfaces and non-Euclidean geometry
2:00pm|Simonyi Hall 101 and Remote Access
The classification of geometric structures on manifolds
naturally leads to actions of automorphism groups, (such as mapping
class groups of surfaces) on "character varieties" (spaces of
equivalence classes of representations of surface groups).
Jus...
A mathematical approach to some problems in neurobiology
2:00pm|Simonyi Hall 101 and Remote Access
I will discuss some questions of interest in neuroscience, seen
through the lens of mathematics. No prior knowledge of neuroscience
is needed for this talk. Two of the most basic visual capabilities
of primates are orientation selectivity, i.e., the...
PDEs vs. Geometry: analytic characterizations of geometric properties of sets
2:00pm|Simonyi Hall 101 and Remote Access
In this talk we will discuss connections between the geometric
and analytic/PDE properties of sets. The emphasis is on
quantifiable, global results which yield true equivalence between
the geometric and PDE notions in very rough scenarios,
including...
2:00pm|Simonyi Hall 101 and Remote Access
Morrey’s conjecture arose from a rather innocent looking
question in 1952: is there a local condition characterizing
"ellipticity” in the calculus of variations? Morrey was not able to
answer the question, and indeed, it took 40 years until
first...
No seminar: Presidents' Day
2:00pm|Simonyi Hall 101 and Remote Access
A Gentle Approach to Crystalline Cohomology
2:00pm|Simonyi Hall 101 and Remote Access
Let X be a smooth affine algebraic variety over the field C of
complex numbers (that is, a smooth submanifold of C^n which can be
described as the solutions to a system of polynomial equations).
Grothendieck showed that the de Rham cohomology of X...
The orbit method, microlocal analysis and applications to L-functions
2:00pm|Simonyi Hall 101 and Remote Access
I will describe how the orbit method can be developed in a
quantitative form, along the lines of microlocal analysis, and
applied to local problems in representation theory and global
problems involving the analysis of automorphic forms. This
talk...
No seminar: Morse lectures
2:00pm|Simonyi Hall 101 and Remote Access
On the unpredictability of fluid motions
2:00pm|Simonyi Hall 101 and Remote Access
The fundamental equations of fluid dynamics exhibit
non-uniqueness. Is this a mathematical fluke, or do the equations
fail to uniquely predict the motion of fluids? In this colloquium,
we present recent mathematical and physical progress toward...
2:00pm|Simonyi Hall 101 and Remote Access
2:00pm|Simonyi Hall 101 and Remote Access
Thresholds for increasing properties of random structures are a
central concern in probabilistic combinatorics and related
areas. In 2006, Kahn and Kalai conjectured that for any
nontrivial increasing property on a finite set, its threshold
is...
Members’ Seminar
Completing the Bernstein Program (A Geometric Conjecture within the Representation Theory of p-adic Groups)
Approximation algorithms and Grothendieck type inequalities
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...
Local Models of Shimura Varieties
George Pappas
Blow up in a 3-D "toy" model for the Euler equations
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...
A New Characterization of Sobolev Spaces
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...
p-Adic Multiple Zeta Values
A Liouville Type Result for some Conformally Invariant Fully Nonlinear Equations
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.
Polynomiality Properties of Type A Weight and Tensor Product Multiplicities
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...
Exotic Smooth Structures on Rational Surfaces
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'...
Iterated Integrals and Algebraic Cycles
It will be on some constructions in the candidate category of
mixed Tate Motives constructed by Bloch and Kriz.
Motivic Integration, Constructible Functions, and Stringy Chern Classes
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...
On some Properties of the Nottingham Group
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...
Generalized Teichmueller Spaces
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...
Quantitative Symplectic Geometry
Universality for Mathematical and Physical Systems
Percy Deift
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...
Random Walks and Equidistribution on Lie Groups
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.
The Deligne-Simpson Problem and Double Affine Hecke Algebras
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...
Deformation of Yang-Mills Theory Via Pure Spinors
Arithmetic Progressions and Nilmanifolds
Multivariable Mahler Measure and Regulators
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...
Counting Polynomial Configurations on Dense Subsets of the Integers
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...
Generation of Finite Simple Groups and Derangements
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...
String Topology and Closed Geodesics
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...
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...
Some Results on Complete Symmetric Varieties
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...
On the p-Adic Spectra of Some Hecke Operators
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...
The Two-Dimensional Ising Model and SLE
Open Gromov-Witten Theory of the Quintic Threefold
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...
Equidistribution Problems on Siegel Modular Varieties
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...
We introduce and construct the "AC geometry" from the Gaussian
free field and use it to prove various facts about Schramm-Loewner
evolutions.
Random Geometry and SLE II
We introduce and construct the "AC geometry" from the Gaussian
free field and use it to prove various facts about Schramm-Loewner
evolutions.
Regularity and Analyticity for the dissipative Quasi-Geostrophic Equations