2018
Apr
09

# Seminars

2018
Mar
28

# Analysis Seminar: TBA

12:00pm to 1:00pm

2018
Jun
06

# Analysis Seminar: Michal Pnueli

12:00pm to 1:00pm

2018
May
02

# Analysis Seminar: Bo'az Klartag

12:00pm to 1:00pm

2018
Feb
05

2018
Feb
26

# HD-Combinatorics Special Day on On Random groups and property T (organized by Izhar Oppenheim)

(All day)

## Location:

Room 130, IIAS, Feldman Building, Givat Ram

10:00-11:00:

**Izhar Oppenheim**, Introduction to Property (T)

11:30-12:30:

**Izhar Oppenheim,**Introduction to Random Groups

14:00-16:00:

**Izhar Oppenheim,**Property (T) and hyperbolicity for random groups in the permutation model

2018
Jan
31

2016
Jun
09

# Joint Amitsur Algebra&NT Seminar: Shai Haran (Technion), "New foundations for geometry"

12:00pm to 1:15pm

## Location:

Manchester Building (Ross 63), Jerusalem, Israel

*** Please note the LOCATION ***
We shall give a simple generalization of commutative rings. The
category GR of such generalized rings contains ordinary commutative
rings (fully, faithfully), but also the "integers" and the "residue
field" at a real or complex place of a number field ; the "field with
one element" F1 (the initial object of GR) ; the "Arithmetical
Surface" (the categorical sum of the integers Z with them self). We
shall show this geometry sees the real and complex places of a number
field K : the valuation sub GR of K correspond to the finite and

2016
Apr
21

# Amitsur Algebra: Konstantin Golubev (HU)

12:00pm to 1:15pm

## Location:

Manchester Building (room 209), Jerusalem, Israel

Title: Spectral approach to the chromatic number of a simplicial complex
Abstract: In this talk, we'll summarize results obtained in recent years in a pursuit for spectral bounds for the chromatic number of a simplicial complex. As the principal application, we'll show that Ramanujan complexes serve as family of explicitly constructed complexes with large girth and large chromatic number. We'll also present other results, such as a bound on the expansion and a bound on the mixing of a complex, and refer to open questions.
Based on joint work with S.Evra, A.Lubotzky and O.Parzanchevski.

2016
Jan
07

# Amitsur Algebra: Gili Schul (Hebrew U): Rapid expansion in finite simple groups

12:00pm to 1:15pm

## Location:

Manchester Building (room 209), Jerusalem, Israel

Title: Rapid expansion in finite simple groups
Abstract: We show that small normal subsets $A$ of finite simple groups expand
very rapidly -- namely, $|A^2| \ge |A|^{2-\epsilon}$, where $\epsilon >0$ is
arbitrarily small.
Joint work with M. W. Liebeck and A. Shalev

2018
Jan
25

# Special seminar: Sylvian Cappell (NYU) "What can be the fixed point sets of a given finite group acting on a non-simply-connected compact space?"

10:30am to 11:30am

## Location:

Ross 70

We will report on a joint work with Shmuel Weinberger of U. of Chicago & Min Yan of Hong Kong U. of Sci. & Tech.

2016
Jun
16

# Amitsur Algebra: Gili Golan, "The generation problem in Thompson group F"

12:00pm to 1:15pm

## Location:

Manchester Building (room 209), Jerusalem, Israel

We show that the generation problem in Thompson group F is decidable, i.e., there is an algorithm which decides if a finite set of elements of F generates the whole F. The algorithm makes use of the Stallings 2-core of subgroups of F, which can be defined in an analogue way to the Stallings core of subgroups of a free group. An application of the algorithm shows that F is a cyclic extension of a group K which has a maximal elementary amenable subgroup B. The group B is a copy of a subgroup of F constructed by Brin.

2016
Apr
07

# Amitsur Algebra: Ayala Byron (HUJI), "Definable fields in the free group"

12:00pm to 1:15pm

## Location:

Manchester Building (room 209), Jerusalem, Israel

Abstract: In the early 2000s Sela proved that all non-abelian free groups share a common first-order theory. Together with R. Sklinos, we use tools developed in his work to show that no infinite field is definable in this theory. In this talk we will survey the line of proof for a formal solution theorem for a simple sort of definable sets, that have a structure of a hyperbolic tower, and use it to characterize definable sets that do not carry a definable structure of an abelian group.

2018
Apr
25

2018
Jan
30