2019 Aug 07

NT & AG Seminar: Sandeep Varma "Bernstein projectors for SL(2)"

2:00pm to 3:00pm


Ross 70
Let G be the group SL(2) over a finite extension F of Q_p, p odd. For a fixed r ≥ 0, we identify the elements of the Bernstein center of G supported in the Moy-Prasad G-domain G_{r^+}, by characterizing them spectrally.
We study the behavior of convolution with such elements on orbital integrals of functions in C^∞_c(G(F)), proving results in the spirit of semisimple descent.
These are ‘depth r versions’ of results proved for general reductive groups by J.-F. Dat, R. Bezrukavnikov, A. Braverman and D. Kazhdan.
2019 Dec 19

Colloquium Zabrodsky lecture 1: Paul Seidel (MIT)- The symplectic topologist as a dynamicist

2:30pm to 3:30pm


Manchester Building (Hall 2), Hebrew University Jerusalem
The development of symplectic topology was motivated by Hamiltonian mechanics. It has been particularly successful in addressing one specific aspect, namely fixed points and periodic points of discrete-time Hamiltonian systems. I will explain how such applications work, both in older and more recent examples.
2020 Jan 16

Colloquium Dvoretzky lecture: Sylvia Serfaty (NYU): Systems of points with Coulomb interactions

2:30pm to 3:30pm


Manchester Building (Hall 2), Hebrew University Jerusalem

Title: Systems of points with Coulomb interactions
Abstract:  Large ensembles of points with Coulomb interactions arise in various settings of condensed matter physics, classical and quantum mechanics, statistical mechanics, random matrices and even approximation theory, and they give rise to a variety of questions pertaining to analysis, Partial Differential Equations and probability.
2019 Jun 27

Groups and Dynamics seminar: Asaf Katz (Chicago) - An application of Margulis' inequality to effective equidistribution.

11:30am to 12:45pm

Abstract: Ratner's celebrated equidistribution theorem states that the trajectory of any point in a homogeneous space under a unipotent flow is getting equidistributed with respect to some algebraic measure. In the case where the action is horospherical, one can deduce an effective equidistribution result by mixing methods, an idea that goes back to Margulis' thesis.

2019 Jun 23

Special Talk - Saharon Shelah

4:00pm to 6:00pm


Manchester Building, Room 110

Simplicity and universality

Fixing a complete first order theory T, countable for transparency, we had known quite well for which cardinals T has a saturated model. This depends on T of course - mainly of
whether it is stable/super-stable. But the older, precursor notion of having
 a universal notion lead us to more complicated answer, quite partial so far, e.g
the strict order property and even SOP_4 lead to having "few cardinals"
(a case of GCH almost holds near the cardinal). Note  that eg GCH gives a complete
2019 Jun 18

Dynamics and probability: David Jerison (MIT) - Localization of eigenfunctions via an effective potential

2:00pm to 3:00pm


Ross 70
We discuss joint work with Douglas Arnold, Guy David, Marcel Filoche and Svitlana Mayboroda.
Consider for the operator $L = -\Delta + V$ with periodic boundary conditions, and more
generally on the manifold with or without boundary. Anderson localization, a significant feature
of semiconductor physics, says that the eigenfunctions of $L$ are exponentially localized with
high probability for many classes of random potentials $V$. Filoche and Mayboroda introduced the