2019 Mar 28

Basic Notions: Benjamin Weiss (HUJI) "Groups with property T have and "cost" of equivalence relations"

4:00pm to 5:15pm

Location:

Ross 70
The cost of a measure-preserving equivalence relation is a quantitative measure of its complexity. I will
explain what the cost is and then discuss a recent result of Tom Hutchcroft and Gabor Pete in which they construct,
for any group with property T, a free ergodic measure preserving action with cost 1.
2019 Mar 25

NT & AG Lunch: Ehud DeShalit "An overview of class field theory, II"

1:00pm to 2:00pm

Location:

Faculty lounge, Math building
Class field theory classifies abelian extensions of local and global fields
in terms of groups constructed from the base. We shall survey the main results of class
field theory for number fields and function fields alike. The goal of these introductory lectures
is to prepare the ground for the study of explicit class field theory in the function field case,
via Drinfeld modules.
I will talk for the first 2 or 3 times.
2019 Mar 26

T&G: Vivek Shende (Berkeley), Quantum topology from symplectic geometry

1:00pm to 2:30pm

Location:

Room 110, Manchester Building, Jerusalem, Israel
The discovery of the Jones polynomial in the early 80's was the beginning of quantum topology'': the introduction of various invariants which, in one sense or another, arise from quantum mechanics and quantum field theory. There are many mathematical constructions of these invariants, but they all share the defect of being first defined in terms of a knot diagram, and only subsequently shown by calculation to be independent of the presentation. As a consequence, the geometric meaning has been somewhat opaque.
2019 Mar 27

Logic Seminar - Shlomo Eshel

11:00am to 1:00pm

Location:

Ross 63
Uniform definability of types over finite sets

Uniform definability of types over finite sets (UDTFS) is a property of formulas which implies NIP and characterizes NIP in the level of theories (by Chernikov and Simon).

In this talk we will prove that if T is any theory with definable Skolem functions, then every dependent formula phi has UDTFS. This result can be seen as a translation of a result of Shay Moran and Amir Yehudayof in machine learning theory to the logical framework.
2019 Jun 12

Logic Seminar - Moshe Illouz

11:00am to 1:00pm

Location:

Ross 63

Categoricity relative to order and order stability

In this talk we will show a generalization of the notion of stability and categoricity relative to the order. One of the natural questions is whether categoricity implies stability, just like in the regular case. We will show that this is not true generally, by using a result of Pabion on peano arithmetic. We are also going to see some specific cases where categoricity relative to the order implies stability.
2019 Jun 05

Logic Seminar - Oren Kalish

11:00am to 1:00pm

Location:

Ross 63

Tight weakly o-minimal structures

We introduce a class of weakly o-minimal expansions of groups, called tight structures. We prove that the o-minimal completion of a tight structure is linearly bounded.
2019 May 22

Logic Seminar - Shahar Oriel

11:00am to 1:00pm

Location:

Ross 63
An omega-categorical strictly stable pseudo-plane

Lachlan conjectured that any omega-categorical stable theory is even omega-stable. Later in 1980 it was shown that there is no omega-categorical omega-stable pseudo plane. In 1988, Hrushovski refuted Lachlan's conjecture by constructing an omega-categorical, strictly stable pseudo-plane.

We will give a quick overview of the construction and try to use this example to test if some properties of omega-categorical  omega-stable theories lift to omega-categorical stable theories.
2019 Apr 03

Logic Seminar - Tomasz Rzepecki

11:00am to 1:00pm

Location:

Ross 63

G-compactness, hereditary G-compactness and related phenomena

The notion of G-compactness, along with the Galois groups, was introduced by Lascar in order to find a sufficient condition under which a first order theory can be recovered from the category of its models.
I will recall this notion. In order to do that, I will also recall various classical notions of strong types, and possibly the Galois group of the theory (and briefly discuss their importance).
2019 Jun 26

Logic Seminar - Nick Ramsey

11:00am to 1:00pm

Location:

Ross 63
Possibilities for a theory of independence beyond NSOP_1 and NTP_2
2019 Mar 20

Logic Seminar - Spencer Unger

11:00am to 1:00pm

Location:

Ross 63

Stationary reflection and the singular cardinals hypothesis.
2019 Jun 19

Logic Seminar - Shlomo Eshel

11:00am to 1:00pm

Location:

Ross 63
A  generalization of the Szemeredi-Trotter theorem to o-minimal expansions of fields
2019 May 29

11:00am to 1:00pm

Location:

Ross 63
Pseudo-o-minimality and pseudo-finite sets.
2019 May 01

Logic Seminar - Mirna Dzamonja

11:00am to 1:00pm

Location:

Ross 63

Two logics for singular cardinals
2019 May 15

Logic Seminar - Shimon Garti

11:00am to 1:00pm

Location:

Ross 63

On the cofinality of some classical cardinal characteristics.

We will try to prove two results about the possible cofinality of cardinal characteristics.
The first result is about the ultrafilter number, and this is a part of a joint work with Saharon Shelah.
The second is about Galvin's number, and this is a joint work with Yair Hayut, Haim Horowitz and Menachem Magidor.
2019 Mar 18

Special course: A. Goncharov (Yale, visiting Einstein Institute of Mathematics) "Quantum geometry of moduli spaces of local systems on surfaces and representation theory"

Repeats every week every Monday until Mon Apr 29 2019 except Mon Apr 22 2019.
4:00pm to 6:00pm

4:00pm to 6:00pm
4:00pm to 6:00pm
4:00pm to 6:00pm
4:00pm to 6:00pm
4:00pm to 6:00pm

Location:

Ross 70

Abstract. This is a joint work with Linhui Shen.
A decorated surface is an oriented surface with punctures and a finite collection of special points on the boundary, considered modulo isotopy.
Let G be a split adjoint group. We introduce a moduli space Loc(G,S) of G-local systems on a decorated surface S, which reduces to the character variety when S has no boundary, and quantize it.