2020 Mar 16

# NT Seminar - Sam Chow - CANCELLED!!!

2:30pm to 3:30pm

## Location:

Ross 70

Title. Dyadic approximation in the Cantor set

Abstract. We investigate the approximation rate of a typical element of the Cantor set by dyadic rationals. This is a manifestation of the times two times three phenomenon, and is joint work with Demi Allen and Han Yu.
2020 Apr 01

# Analysis Seminar: Cancelled

12:00pm to 1:00pm

Ross 70
2020 Mar 23

(All day)

2020 Jan 19

# Game theory seminar: Computational Design Principles of Cognition (Yuval Hart)

2:00pm to 3:00pm

## Location:

Elath Hall, 2nd floor, Feldman Building
Driven by recent technological advancements, behavior and brain activity can now be measured at an unprecedented resolution and scale. This “big-data” revolution is akin to a similar revolution in biology. In biology, the wealth of data allowed systems-biologists to uncover the underlying design principles that are shared among biological systems. In my studies, I apply design principles from systems-biology to cognitive phenomena. In my talk I will demonstrate this approach in regard to creative search.
2020 Jan 14

# T&G: Pavel Etingof (MIT), Short star-products for filtered quantizations

1:00pm to 2:30pm

## Location:

Room 209, Manchester Building, Jerusalem
Motivated by three-dimensional N=4 superconformal field theory, in 2016 Beem, Peelaers and Rastelli considered short even star-products for homogeneous symplectic singularities (more precisely, hyper-Kahler cones) and conjectured that they exist and depend on finitely many parameters. We prove the dependence on finitely many parameters in general and existence for a large class of examples, using the connection of this problem with zeroth Hochschild homology of quantizations suggested by Kontsevich.
2020 Jan 28

# Special Talk: Rita Gitik (University of Michigan) : "Geodesic triangles in the hyperbolic plane."

11:00am to 12:00pm

## Location:

Ross 70

Let M be an orientable hyperbolic surface without boundaryand let c be a closed geodesic in M.

We prove that any side of any triangle formed by distinctlifts of c in the hyperbolic plane is shorter than c.

2020 Jan 16

# Basic Notions: Cy Maor (HUJI) "Infinite dimensionalRiemannian geometry in hydrodynamics and shape analysis".

4:00pm to 5:15pm

## Location:

Ross 70
In the mid-18th century, Euler derived hisfamous equations of motion of an incompressible fluid, one of the most studiedequations in hydrodynamics. More than 200 years later, in 1966, Arnold observedthat they are, in fact, geodesic equations on the (infinite dimensional)Lie group of volume-preserving diffeomorphisms of a manifold, endowed with acertain right-invariant Riemannian metric.
2020 Jan 30

# Basic Notions: Cy Maor (HUJI) "Infinite dimensional Riemannian geometry in hydrodynamics and shape analysis".

4:00pm to 5:15pm

## Location:

Ross 70
In the mid-18th century,Euler derived his famous equations of motion of an incompressible fluid, one ofthe most studied equations in hydrodynamics. More than 200 years later, in1966, Arnold observed that they are, in fact, geodesic equations on the(infinite dimensional) Lie group of volume-preserving diffeomorphisms of amanifold, endowed with a certain right-invariant Riemannian metric.
2020 Jan 08

# Logic Seminar - Kyle Gannon

11:00am to 1:00pm

## Location:

Ross building - Room 63
Kyle Gannon will speal about Keisler measures in and around NIP.

Abstract:
2020 Jan 23

# Groups & Dynamics Seminar. POSTPONED

10:00am to 11:00am

## Location:

Ross 70 a
A countable group is said to be homogeneous if whenever tuples of elements u, v satisfy the same first-order formulas there is an automorphism of the group sending one to the other. We had previously proved with Rizos Sklinos that free groups are homogeneous, while most surface groups aren't. In a joint work with Ayala Dente-Byron, we extend this to give a complete characterization of torsion-free hyperbolic groups that are homogeneous.
2020 Jan 05

# Game theory seminar: Monotonic Norms and Orthogonal Issues in Multidimensional Voting (Benny Moldovanu)

2:00pm to 3:00pm

## Location:

Elath Hall, 2nd floor, Feldman Building
We study issue-by-issue voting and robust mechanism design in multidimensional frameworks where privately informed agents
have preferences induced by general norms. We uncover the deep connections between dominant strategy incentive compatibility (DIC) on the one hand,
and several geometric/functional analytic concepts on the other. Our main results are:
1) Marginal medians are DIC if and only if they are calculated
with respect to coordinates defined by a basis such that the norm is orthant-monotonic in the associated coordinate system.
2020 Jan 01

# Logic Seminar - Spencer Unger

11:00am to 1:00pm

## Location:

Ross building - Room 63
2020 May 14

# Colloquium: Henri Berestycki (EHESS)

2:30pm to 3:30pm

## Location:

Manchester Building (Hall 2), Hebrew University Jerusalem
2020 Mar 18

# Analysis Seminar: Cancelled

12:00pm to 1:00pm

## Location:

Ross 70
Abstract:

Weprove eigenfunction and quasimode estimates on compact Riemannian manifolds for Schr\”odingeroperators, $H_V=-\Delta_g+V$ involving critically singular potentials $V$ which weassume tobe in $L^{n/2}$ and/or the Kato class ${\mathcal K}$.  Our proof is basedon modifying the oscillatory integral/resolvent approachthat was used to study the case where $V \equiv 0$ using recently developedtechniques by many authorsto study variable coefficient analogs of the uniform Sobolev estimates ofKenig, Ruiz and the speaker.

2020 Jan 02

# Tamar Bar-On (BIU): Profinite completion of free profinite groups

12:00pm to 1:00pm

## Location:

Seminar room 209, Manchester Building, Givat ram

Abstract: The profinite completion of a free profinite group on an infinite set of generators is a profinite group of greater rank. However, it is still unknown whether it is a free profinite group as well. I am going to present some partial results regarding this question.