Events & Seminars

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 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).
2017 Mar 08

Logic seminar - Yair Hayur, "Radin Forcing and model without weak diamond"

4:00pm to 6:00pm

Location: 

Ross 70
Abstract: We continue with the topic of the previous week. We will define the Radin forcing, discuss (without proof) and its basic properties. We will give Woodin's proof for the consistency of the existence of strong inaccessible without diamond and show how to strengthen it to the consistency of strong inaccessible without weak diamond.
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 02

Logic Seminar - Chloe Perin - "Forking in the free group"

12:00pm to 2:00pm

Location: 

Ross 63
Sela proved that the theory of free groups is stable. It is thus natural to wonder what the independence relation looks like. Together with Sklinos, we worked out a complete characterization of forking independence in the standard model (over any set of parameters) in terms of an algebraic-geometric object called the JSJ decomposition, which encodes all the splittings of the group as an amalgamated product or an HNN extension relative to the parameter set. In the talk we will try to give an idea of the proof over some examples.
2018 May 21

Combinatorics: Daniel Kalmanovich and Or Raz (HU) "2 talks back-to-back"

11:00am to 12:30pm

Location: 

IIAS, Eilat hall, Feldman Building, Givat Ram
First speaker: Daniel kalmanovich, HU Title: On the face numbers of cubical polytopes Abstract: Understanding the possible face numbers of polytopes, and of subfamilies of interest, is a fundamental question. The celebrated g-theorem, conjectured by McMullen in 1971 and proved by Stanley (necessity) and by Billera and Lee (sufficiency) in 1980-81, characterizes the f-vectors of simplicial polytopes.
2018 Jun 05

Tom Meyerovitch (BGU): On expansivness, topological dimension and mean dimesnion

2:15pm to 3:15pm

Location: 

Ross 70
Expansivness is a fundamental property of dynamical systems. It is sometimes viewed as an indication to chaos. However, expansiveness also sets limitations on the complexity of a system. Ma\~{n}'{e} proved in the 1970’s that a compact metric space that admits an expansive homeomorphism is finite dimensional. In this talk we will discuss a recent extension of Ma\~{n}'{e}’s theorem for actions generated by multiple homeomorphisms, based on joint work with Masaki Tsukamoto. This extension relies on a notion called “topological mean dimension’’ , introduced by Gromov and

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