Past Events
Abstract
Degree-d multivariate polynomials over small finite fields are of central importance in theoretical computer science. And yet they retain many mysteries; for example, their Fourier spectra are very poorly understood. We will discuss the so-called "Fourier growth" of such functions…
In the 1970's dihedral representations of knot groups were used to define twisted signature-type invariants which generalize the older invariants of Levine and Tristram. The most prominent examples are the Casson-Gordon invariants, which provide obstructions to being topologically slice as well…
Abstract: This is a talk about concavity and convexity of trace functionals. In a celebrated paper in 1973, Lieb proved what we now call Lieb's Concavity Theorem and resolved a conjecture of Wigner, Yanase and Dyson in 1963. This result, together with its many extensions, has found plenty of…
Abstract: Take an irrational rotation of the two-sphere; it only has the north and south poles as its periodic points. However, Franks proved that for any area-preserving diffeomorphism of the two-sphere, if it has more than two fixed points, then it must have infinitely many periodic…
A nodal domain of a Laplacian eigenvector of a graph is a maximal connected component where it does not change sign. Sparse random regular graphs have been proposed as discrete toy models of "quantum chaos", and it has accordingly been conjectured by Y. Elon and experimentally observed by Dekel…
We prove the Multiplicity One Conjecture for mean curvature flows of surfaces in R^3. Specifically, we show that any blow-up limit of such mean curvature flows has multiplicity one. This has several applications. First, combining our work with results of Brendle and Choi-Haslhofer-Hershkovits-…
Continuing from last week, we cover Chapter 1 of ‘Semiclassical Analysis’ by Guillemin and Sternberg. We are interested in solving a hyperbolic linear partial differential equation involving a time variable. We reduce it to an ‘eikonal equation’, which we can solve locally by finding a…
I will report on my joint work in progress with Lue Pan which proves that the part of the rational p-adic completed cohomology of a general Shimura variety that is locally analytic with "sufficiently regular" infinitesimal weights is concentrated in the middle degree. I will begin with some…
Abstract: In recent years several groups of authors introduced various invariants that are based on Lagrangian Floer homology of a symmetric product of a symplectic manifold. In this talk, I will introduce Heegaard Floer symplectic cohomology (HFSH), an invariant of a Liouville domain M…