2018 May 29

# Yuri Lima (Paris 11): Symbolic dynamics for non-uniformly hyperbolic systems with singularities

2:15pm to 3:15pm

## Location:

Ross 70
Symbolic dynamics is a tool that simplifies the study of dynamical systems in various aspects. It is known for almost fifty years that uniformly hyperbolic systems have good'' codings. For non-uniformly hyperbolic systems, Sarig constructed in 2013 good'' codings for surface diffeomorphisms. In this talk we will discuss some recent developments on Sarig's theory, when the map has discountinuities and/or critical points, such as multimodal maps of the interval and Bunimovich billiards.
2018 May 08

# Dynamics Seminar: Yinon Spinka (TAU): Finitary codings of Markov random fields

2:15pm to 4:15pm

## Location:

Ross 70
Let X be a stationary Z^d-process. We say that X is a factor of an i.i.d. process if there is a (deterministic and translation-invariant) way to construct a realization of X from i.i.d. variables associated to the sites of Z^d. That is, if there is an i.i.d. process Y and a measurable map F from the underlying space of Y to that of X, which commutes with translations of Z^d and satisfies that F(Y)=X in distribution. Such a factor is called finitary if, in order to determine the value of X at a given site, one only needs to look at a finite (but random) region of Y.
2018 Apr 12

# Special talk: Yonatan Harpaz (Paris 13) - "Small extensions in algebra and topology"

## Lecturer:

Yonatan Harpaz (Paris 13)
1:15pm to 2:15pm

## Location:

Ross 70
Abstract: In this talk, we will discuss the notion of small extensions in its various incarnations, from torsors under abelian groups to square-zero extensions of algebras. We will then focus on the somewhat less familiar case of small extensions of ∞-categories. Our main goal is to make this abstract concept concrete and intuitive through a variety of examples. In particular, we will advocate the point of view that small extensions of  ∞-categories offer a unifying perspective in understanding many constructions appearing in obstruction, classification, and deformation theoretic problems
2018 Apr 16

# HD-Combinatorics Special Day on Grassman Expanders and Unique Games (organized by Irit Dinur)

(All day)

## Location:

Room 130, IIAS, Feldman Building, Givat Ram
2018 Apr 11

4:00pm to 6:00pm

Ross 70A
2018 Apr 15

# GAME THEORY AND MATHEMATICAL ECONOMICS RESEARCH SEMINAR: Ron Peretz, Bar Ilan University: "The Rate of Innovation Diffusion in Social Networks (joint with Itai Arieli, Yakov Babichenko, and Peyton H Young)"

1:30pm to 2:30pm

## Location:

Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus
2018 May 22

# Dynamics Lunch: Tsviqa Lakrec (Huji)

12:00pm to 1:00pm

## Location:

Manchester lounge
2017 Nov 01

# Logic Seminar - Immanuel BenPorat - "Cardinal conditions for strong Fubini theorems"

11:00am to 1:00pm

## Location:

Math209
This talk will be largely based on a paper by Joseph Shipman with the same title. We will discuss some variations of Fubini type theorems. The focus will be on what is known as "strong Fubini type theorems". Apparently these versions were proved to be independent of ZFC,and our main aim will be to sketch a proof of this result. We will assume basic knowledge in measure theory. Aside from that, the material is rather self contained.
2018 Jun 06

# Logic Seminar - Gabriel Conant - "Local NIP group theory and pseudofinite groups"

11:00am to 1:00pm

## Location:

Ross 63
Much of the early development of model theoretic stability theory was motivated by stable groups, which include algebraic groups as guiding examples. Later work of Hrushovski and Pillay showed that many tools from stable group theory can be adapted to the local setting, where one works around a single stable formula rather than a stable theory. More recently, groups definable in NIP theories have been intensively studied, bringing back the importance of measures in model theory. On the other hand, local NIP group theory is not as well understood.
2017 May 24

# Logic seminar - Katrin Tent, "Ample geometries of finite Morley rank"

4:00pm to 6:00pm

## Location:

Ross 70
Abstract: I will explain the model theoretic notion of ampleness and present the geometric context of recent constructions.
2017 Dec 27

# Logic Seminar - Omer Ben-Neria - "Singular Stationarity and Set Theoretic Generalizations of Algebras"

11:00am to 1:00pm

## Location:

Ross 63
Abstract: The set theoretic generalizations of algebras have been introduced in the 1960s to give a set theoretic interpretation of usual algebraic structures. The shift in perspective from algebra to set theory is that in set theory the focus is on the collection of possible algebras and sub-algebras on specific cardinals rather than on particular algebraic structures. The study of collections of algebras and sub-algebras has generated many well-known problems in combinatorial set theory (e.g., Chang’s conjecture and the existence of small singular Jonsson cardinals).
2016 Dec 21

# Logic seminar - Ur Benari-Tish, "The modal logic of σ-centered forcing"

4:00pm to 6:00pm

## Location:

Ross 70
The modal logic of σ-centered forcing Speaker: Ur Benari-Tish
2017 Jul 10

# Special logic seminar - Noa Lavi, "Independent chapters in dependent theories"

11:00am to 1:00pm

## Location:

Ross 70
This talk is about three published papers of mine that form my phd. In the first two chapters I focus in the model theory of real closed fields and in the third one I take one step back and investigate in greater genearility dependent theories. The results are the following: 1. Boundedness criterion for rational functions over generalized semi-algebraic sets in real closed fields. 2. Positivity criterion for polynomials over generalized semi-algebraic sets in real closed valued fields.
2018 May 16

# Logic Seminar - Shlomo Eshel - "The Strong Erdos-Hajnal property and the incidence relation"

11:00am to 1:00pm

## Location:

Ross 63
In my master thesis we (Prof' Kobi Peterzil and I) investigated a problem in combinatorial geometry using tools from model theory. Following the article of Chernikov and Starchenko, "Regularity lemma for distal structures", we consider the Strong Erdos-Hajnal property for the incidence relation of points and lines in R^2. In particular, we compute a constant d such that for every finite sets of points P and lines L, with |P|,|L| > 2, there are a subsets P' of P and L' of L such that no point in P' lies on a line from L', and such that |P'|>d|P| , |L'|>d|L|.
2017 Dec 06

# Logic Seminar - Daoud Siniora - "Automorphism groups of homogeneous structures"

11:00am to 1:00pm

## Location:

Math 209
A special class among the countably infinite relational structures is the class of homogeneous structures. These are the structures where every finite partial isomorphism extends to a total automorphism. A countable set, the ordered rationals, and the random graph are all homogeneous.