# Events & Seminars

2020
Jan
16

4:00pm to 5:15pm

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
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.

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

2020
May
14

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. Read more about Analysis Seminar: Cancelled

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.

2020
Jan
02

# Groups & Dynamics Seminar. Maria Gerasimova (BIU) : “Isoperimetry, Littlewood functions, and unitarisability of group”

10:00am to 11:00am

## Location:

Ross 70 a

Let Γ be a discrete group. A group Γ is called unitarisable if for any Hilbert space H and

any uniformly bounded representation π : Γ → B(H) of Γ on H there exists a bounded operator

S : H → H such that S^{−1}π(g)S is a unitary representation for any g ∈ Γ. It is well known that

amenable groups are unitarisable. It has been open ever since whether amenability characterises unitarisability of groups.

Dixmier: Are all unitarisable groups amenable?

One of the approaches to study unitarisability is related to the space of the Littlewood functions

any uniformly bounded representation π : Γ → B(H) of Γ on H there exists a bounded operator

S : H → H such that S^{−1}π(g)S is a unitary representation for any g ∈ Γ. It is well known that

amenable groups are unitarisable. It has been open ever since whether amenability characterises unitarisability of groups.

Dixmier: Are all unitarisable groups amenable?

One of the approaches to study unitarisability is related to the space of the Littlewood functions

2020
Jan
08

# Special Analysis Seminar: Andrew Ahn (MIT) "Largest Singular Values of Products of \beta-Ensembles"

2:00pm to 3:00pm

## Location:

221B

Title:Largest Singular Values of Products of \beta-Ensembles

2020
Mar
31

# Or Landesberg

12:00pm to 1:00pm

2019
Dec
26

2019
Dec
25

# Special dynamics seminar: Asaf Katz (Chicago) - Measure rigidity of Anosov flows via the factorization method

1:30pm to 3:30pm

## Location:

Ross 70

Title - Measure rigidity of Anosov flows via the factorization method.

Abstract: Anosov flows are central objects in dynamics, generalizing the basic example of a geodesic flow over a Riemann surface.

In the talk we will introduce those flows and their dynamical behavior.

Moreover, we show how the factorization method, pioneered by Eskin and Mirzakhani in their groundbreaking work about measure rigidity for the moduli space of translation surfaces, can be adapted to smooth ergodic theory and in particular towards the study of Anosov flows.

Abstract: Anosov flows are central objects in dynamics, generalizing the basic example of a geodesic flow over a Riemann surface.

In the talk we will introduce those flows and their dynamical behavior.

Moreover, we show how the factorization method, pioneered by Eskin and Mirzakhani in their groundbreaking work about measure rigidity for the moduli space of translation surfaces, can be adapted to smooth ergodic theory and in particular towards the study of Anosov flows.

2020
Jan
09

# Ted Chinburg (U Penn): Using capacity theory to plug leaks

12:00pm to 1:00pm

## Location:

Manchester Building, Room 209

January 9, 12:00-13:00, Seminar room 209, Manchester building.

2019
Dec
18

# Logic Seminar - Jouko Vaananen

11:00am to 1:00pm

## Location:

Ross building - Room 63

**Jouko Vaananen**will speak about some new infinitary logics.

**On some new infinitary logics**

__Abstract:__