Eventss

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

Location: 

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

Location: 

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
2019 Jun 20

Basic Notions: Hillel Furstenberg (HUJI) : "Affine (Convex) representations and harmonic functions on symmetric spaces." Part 1

4:00pm to 5:15pm

Location: 

Ross 70
Classical group representation theory deals with group actions on linear spaces; we consider group actions on compact convex spaces, preserving topological and convex structure. We focus on irreducible actions, and show that for a large class of groups - including connected Lie groups - these can be determined. There is a close connection between this and the theory of bounded harmonic functions on symmetric spaces and their boundary values.
2019 Jun 27

Basic Notions: Hillel Furstenberg (HUJI) : "Affine (Convex) representations and harmonic functions on symmetric spaces." Part 2

4:00pm to 5:15pm

Location: 

Ross 70
Classical group representation theory deals with group actions on linear spaces; we consider group actions on compact convex spaces, preserving topological and convex structure. We focus on irreducible actions, and show that for a large class of groups - including connected Lie groups - these can be determined. There is a close connection between this and the theory of bounded harmonic functions on symmetric spaces and their boundary values.
2019 Jun 26

Analysis Seminar - Dvoretzky lecture - Assaf Naor "The (in)compatibility of 3 and 5 dimensional Heisenberg geometry with Lebesgue spaces"

12:00pm to 1:00pm

Location: 

Ross 70

Title: The (in)compatibility of 3 and 5 dimensional Heisenberg geometry with Lebesgue spaces
Abstract: The 3-dimensional (discrete) Heisenberg geometry is the shortest-path metric on the infinite graph whose vertex set is the integer grid $\Z^3$ and the neighbors of each integer vector $(a,b,c)$ are the four integer vectors $$(a+ 1,b,c), (a- 1,b,c), (a,b+ 1,c+ a), (a,b- 1,c- a).$$

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