2017
Nov
07

# Events & Seminars

2017
Apr
27

# Basic notions: Raz Kupferman

4:00pm to 5:15pm

Abstract:

The “geometrization" of mechanics (whether classical, relativistic or quantum) is almost as old as modern differential geometry, and it nowadays textbook material.

The “geometrization" of mechanics (whether classical, relativistic or quantum) is almost as old as modern differential geometry, and it nowadays textbook material.

2018
Jan
04

# Basic Notions Seminar: Zlil Sela (HUJI) - "Projection complexes, actions on quasi-trees, and applications to mapping class groups of surfaces" (after Bestvina-Bromberg-Fujiwara).

4:00pm to 5:15pm

## Location:

Ross 70

Projection complexes, actions on quasi-trees, and applications to mapping class groups of surfaces (after Bestvina-Bromberg-Fujiwara).

2017
Mar
02

# Basic Notions: Ori Gurel Gurevich (HUJI) - On Smirnov's proof of conformal invariance of critical percolation

4:00pm to 5:00pm

## Location:

Manchester Building, Lecture Hall 2

Abstract:

Let G be an infinite connected graph. For each vertex of G we decide

randomly and independently: with probability p we paint it blue and

with probability 1-p we paint it yellow. Now, consider the subgraph of

blue vertices: does it contain an infinite connected component?

There is a critical probability p_c(G), such that if p>p_c then almost

surely there is a blue infinite connected component and if p

We will focus on planar graphs, specifically on the triangular

Let G be an infinite connected graph. For each vertex of G we decide

randomly and independently: with probability p we paint it blue and

with probability 1-p we paint it yellow. Now, consider the subgraph of

blue vertices: does it contain an infinite connected component?

There is a critical probability p_c(G), such that if p>p_c then almost

surely there is a blue infinite connected component and if p

__p_c or p<p_c.__We will focus on planar graphs, specifically on the triangular

2018
Jan
11

# Basic Notions: Michael Hopkins (Harvard) - Homotopy theory and algebraic vector bundles

4:00pm to 5:15pm

## Location:

Einstein 2

Abstract: This talk will describe joint work with Aravind Asok

and Jean Fasel using the methods of homotopy theory to construct new

examples of

algebraic vector bundles. I will describe a natural conjecture

which, if

true, implies that over the complex numbers the classification

of algebraic

vector bundles over smooth affine varieties admitting an

algebraic cell

decomposition coincides with the classification of topological

complex vector bundles.

and Jean Fasel using the methods of homotopy theory to construct new

examples of

algebraic vector bundles. I will describe a natural conjecture

which, if

true, implies that over the complex numbers the classification

of algebraic

vector bundles over smooth affine varieties admitting an

algebraic cell

decomposition coincides with the classification of topological

complex vector bundles.

2018
Jan
14

# Kazhdan Sunday seminars: Leonid Polterovich (TAU) "Algebraic methods in symplectic topology"

3:00pm to 5:00pm

## Location:

Ross buildings, Room 70A.

Nick Rozenblyum (Chicago) will talk about Tamarkin's category.

2017
Oct
22

(All day)

2018
Jan
14

# Kazhdan Sunday seminars: Tomer Schlank (HUJI) "Topics in algebraic topology".

11:00am to 1:00pm

## Location:

Ross buildings, Room 70A.

10:00-11:00 We will have a special lecture on string diagrams by Shaul Barkan
11:00-13:00 Asaf Horev will continue his talk about ambidexterity and duality

2016
Jun
16

# Jerusalem Analysis and PDEs - Gilbert Weinstein (Ariel)

1:00pm to 2:00pm

## Location:

Ross 70

Title: Harmonic maps with prescribed singularities and applications to general relativity

Abstract: We will present a general theory of existence and uniqueness for harmonic maps with prescribed singularities into Riemannian manifolds with non-positive curvature. The singularities are prescribed along submanifolds of co-dimension 2. This result generalizes one from 1996, and is motivated by a number of recent applications in general relativity including:

* a lower bound on the ADM mass in terms of charge and angular momentum for multiple black holes;

Abstract: We will present a general theory of existence and uniqueness for harmonic maps with prescribed singularities into Riemannian manifolds with non-positive curvature. The singularities are prescribed along submanifolds of co-dimension 2. This result generalizes one from 1996, and is motivated by a number of recent applications in general relativity including:

* a lower bound on the ADM mass in terms of charge and angular momentum for multiple black holes;

2017
May
25

# Mark Rudelson: Delocalization of the eigenvectors of random matrices.

1:00pm to 2:00pm

## Location:

Ross 70

Abstract: Consider a random matrix with i.i.d. normal entries. Since its distribution is invariant under rotations, any normalized eigenvector is uniformly distributed over the unit sphere. For a general distribution of the entries, this is no longer true. Yet, if the size of the matrix is large, the eigenvectors are distributed approximately uniformly. This property, called delocalization, can be quantified in various senses. In these lectures, we will discuss recent results on delocalization for general random matrices.

2017
Nov
08

# Jerusalem Analysis Seminar: "To infinity and back (a bit)", Jonathan Breuer (HUJI)

12:00pm to 1:00pm

## Location:

Ross 63

Let H be a self-adjoint operator defined on an infinite dimensional Hilbert space. Given some

spectral information about H, such as the continuity of its spectral measure, what can be said about

the asymptotic spectral properties of its finite dimensional approximations? This is a natural (and

general) question, and can be used to frame many specific problems such as the asymptotics of zeros of

orthogonal polynomials, or eigenvalues of random matrices. We shall discuss some old and new results

2016
Dec
29

# Analysis and PDEs Seminar: Svetlana Jitomirskaya (UC Irvine)

1:00pm to 2:00pm

## Location:

Ross 70

Title: Sharp arithmetic spectral transitions and universal hierarchical structure of quasiperiodic eigenfunctions.

Abstract: A very captivating question in solid state physics

is to determine/understand the hierarchical structure of spectral features

of operators describing 2D Bloch electrons in perpendicular magnetic

fields, as related to the continued fraction expansion of the magnetic

flux. In particular, the hierarchical behavior of the eigenfunctions of

the almost Mathieu operators, despite signifi cant numerical studies and

Abstract: A very captivating question in solid state physics

is to determine/understand the hierarchical structure of spectral features

of operators describing 2D Bloch electrons in perpendicular magnetic

fields, as related to the continued fraction expansion of the magnetic

flux. In particular, the hierarchical behavior of the eigenfunctions of

the almost Mathieu operators, despite signifi cant numerical studies and

2017
May
24

# Mark Rudelson: Delocalization of the eigenvectors of random matrices.

2:00pm to 3:00pm

## Location:

רוס 63

Abstract: Consider a random matrix with i.i.d. normal entries. Since its distribution is invariant under rotations, any normalized eigenvector is uniformly distributed over the unit sphere. For a general distribution of the entries, this is no longer true. Yet, if the size of the matrix is large, the eigenvectors are distributed approximately uniformly. This property, called delocalization, can be quantified in various senses. In these lectures, we will discuss recent results on delocalization for general random matrices.

2016
Nov
22

2017
Dec
27

# Jerusalem Analysis Seminar: "Optimal Gaussian Partitions", Elchanan Mossel (MIT)

12:00pm to 1:00pm

## Location:

Ross 70

How should we partition the Gaussian space into k parts in a way that minimizes Gaussian surface area, maximize correlation or simulate a specific distribution. The problem of Gaussian partitions was studied since the 70s first as a generalization of the isoperimetric problem in the context of the heat equation. It found a renewed interest in the context of the double bubble theorem proven in geometric measure theory and due to connection to problems in theoretical computer science and social choice theory. Read more about Jerusalem Analysis Seminar: "Optimal Gaussian Partitions", Elchanan Mossel (MIT)