Upcoming seminars can also be found here.

2018
Jul
11

# Logic Seminar - Assaf Shani - TBA

11:00am to 1:00pm

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Upcoming seminars can also be found here.

2018
Jul
11

11:00am to 1:00pm

2018
Jun
25

(All day)

Feldman Building, Givat Ram

Title for the day: "Quantum ergodicity and spectral theory with a discrete flavour"

9:00-10:50:**Shimon Brooks** (Bar Ilan), "Delocalization of Graph Eigenfunctions"

14:00-15:50:**Elon Lindenstrauss** (HUJI), "Quantum ergodicity on graphs and beyond"

See also the Basic Notions by Elon Lindenstrauss @ Ross 70 (16:30).

Abstract for morning session:

9:00-10:50:

14:00-15:50:

See also the Basic Notions by Elon Lindenstrauss @ Ross 70 (16:30).

Abstract for morning session:

2018
Jun
25

2018
Jun
19

12:00pm to 1:30pm

Room 110, Manchester Buildling, Jerusalem, Israel

We shall discuss several topics regarding symplectic measurements in the classical phase space. In particular: Viterbo's volume-capacity conjecture and its relation with Mahler conjecture, the symplectic size of random convex bodies, the EHZ capacity of convex polytopes (following the work of Pazit Haim-Kislev), and (if time permits) also computational complexity aspects of estimating symplectic capacities.

2018
Jun
19

4:00pm to 6:00pm

Math 209

Abstract: Let V be an irreducible algebraic subvariety of C^n X C^n of
dimension n.
If Schanuel Conjecture holds, under some natural conditions on V, we
show that, if V is defined over the rationals, there exists a in C^n
such that (a, exp(a)) is a generic point of V.

2018
Jun
18

(All day)

Eilat Hall, Feldman Building, Givat Ram

Speakers:

Part I: 10:30 - 12:30

Part II: 14:00 - 15:50

Time permitting, we plan to discuss the following topics (in this order):

1.

* Additive Sparsification and VC dimension

* Multiplicative Sparsification

* Examples: cut weights, cut-dimension of L_1 metrics, general metrics,

and their high-dimensional analogues

2.

2018
Jun
21

4:00pm to 4:00am

2018
Jun
14

4:00pm to 5:15pm

Ross 70

Ergodic theoretic methods in the context of homogeneous dynamics have been highly successful in number theoretic and other applications. A lacuna of these methods is that usually they do not give rates or effective estimates. Einseidler, Venkatesh and Margulis proved a rather remarkable quantitative equidistribution result for periodic orbits of semisimple groups in homogenous spaces that can be viewed as an effective version of a result of Mozes and Shah based on Ratner's measure classification theorem.

2018
Jun
25

4:30pm to 5:45pm

This is the second of two lectures on the paper Einseidler,, Margulis, Mohammadi and Venkatesh https://arxiv.org/abs/1503.05884. In this second lecture I will explain how the authors obtain using property tau (uniform spectral gap for arithmetic quotient) quantitaive equidistribution results for periodic orbits of maximal semisimple groups. Surprisingly, one can then use this theorem to establish property tau...

2019
Mar
13

12:00pm to 1:00pm

2018
Jun
12

1:00pm to 2:30pm

Room 110, Manchester Buildling, Jerusalem, Israel

Open Gromov-Witten (OGW) invariants count pseudoholomorphic maps from a Riemann surface with boundary to a symplectic manifold, with constraints that make sure the moduli space of solutions is zero dimensional. In joint work with J. Solomon (2016-2017), we defined OGW invariants in genus zero under cohomological conditions. In this talk, also based on joint work with J. Solomon, I will describe a family of PDEs satisfied by the generating function of our invariants. We call this family the open WDVV equations.

2018
Jun
11

10:00am to 10:50am

Feldman Building, Givat Ram

In the past decades There has been considerable interest in the probability that two random elements of (finite or certain infinite)
groups commute.
I will describe new works (by myself and by others) on probabilistically nilpotent groups, namely groups in which the probability that [x_1,...,x_k]=1 is positive/bounded away from zero.
It turns out that, under some natural conditions,
these are exactly the groups which have a finite/bounded index
subgroup which is nilpotent of class < k.
The proofs have some combinatorial flavor.

2018
Jun
11

9:00am to 9:50am

Feldman Building, Givat Ram

Let X be the spherical building associated to the group G=GL(n,F) ,
where F is a finite field. We will survey some results on the homology of X with constant and twisted coefficients, and on the corresponding expansion properties.

2018
Jun
11

2:00pm to 3:50pm

Feldman Building, Givat Ram

In this talk we recall Conlon's random construction of sparse 2-dim simplicial complexes arising from Cayley graphs of F_2^t . We check what expansion properties this construction has (and doesn't have): Mixing of random walks, Spectral gap of the 1-skeleton, Spectral gap of the links, Co-systolic expansion and the geometric overlap property.

2018
Jun
04

2:00pm to 3:50pm

Feldman Building, Givat Ram

In this talk we shall review a paper by Gromov and Guth, in which they introduced several ways to measure the geometric complexity of an embedding of simplicial complexes to Euclidean spaces.
One such measurement is strongly related to the notion of high dimensional expanders introduced by Gromov, and in fact, it is based on a paper of Kolmogorov and Barzadin from 1967, in which the notion of an expander graph appeared implicitly.
We shall show one application of bounded degree high dimensional expanders, and present many more open questions arising from the above mentioned paper.