2017 Jan 19

# Amitsur Algebra: Yiftach Barnea, "Old and New Results on Subgroup Growth in Pro-p Groups."

12:00pm to 1:00pm

## Location:

Manchester Building, Room 209
Title: Old and New Results on Subgroup Growth in Pro-p Groups. Abstract: I will survey our current knowledge about subgroup growth in pro-p growth. In particular I will present new solutions to long standing open problems in the area: 1. What is the minimal subgroup growth of non-$p$-adic analytic pro-$p$ groups? (Joint work with Benjamin Klopsch and Jan-Christoph Schlage-Puchta.) 2. What are the subgroup growths of the Grigorchuk group and the Gupta-Sidki groups? (Joint work with Jan-Christoph Schlage-Puchta.)
2017 Jun 22

# Amitsur Algebra: Jan Dobrowolski

12:00pm to 1:00pm

## Location:

Manchester 209
Title: Inp-minimal ordered groups. Abstract. The main goal of the talk is to present the proof of the theorem stating that inp-minimal (left)-ordered groups are abelian. This generalizes a previous result of P. Simon for bi-ordered inp-minimal groups.
2016 Dec 29

# Amitsur Algebra: Igor Rivin, "Random integer matrices"

12:00pm to 1:00pm

## Location:

Manchester Building, Room 209
Title: Random integer matrices Abstract: I will discuss various models of random integer matrices, and their (occasionally surprising) properties. Some of the work discussed is joint with E. Fuchs.
2017 May 04

# Amitsur Algebra: Jasbir Chahal, " A tale of three elliptic curves"

12:00pm to 1:00pm

## Location:

Manchester 209
Title: A tale of three elliptic curves. Abstract: We will show how the arithmetic of three elliptic curves answers three old questions in the Euclidean geometry.
2016 Dec 08

# Amitsur Algebra: George Glauberman (Chicago)

12:00pm to 1:15pm

## Location:

Manchester Building, Room 209
Title: Fixed points of finite groups on modules Abstract: Suppose G is a finite group, p is a prime, S is a Sylow p-subgroup of G, and V is a G-module over a field of characteristic p. In some situations, an easy calculation shows that the fixed points of G on V are the same as the fixed points of the normalizer of S in G. Generalizations of this result have been obtained previously to study the structure of G for p odd. We plan to describe a new generalization for p = 2. (This is part of joint work with J. Lynd that removes the classification of finite simple groups
2017 Mar 02

# Amitsur Algebra: Lev Glebsky, " Almost Congruence Extension Property for subgroups of free groups"

12:00pm to 1:00pm

## Location:

Manchester Building, Room 209
Title: Almost Congruence Extension Property for subgroups of free groups. Abstract. The talk essentially based on: https://arxiv.org/abs/1606.02345 Let G be a group and H
2017 Feb 09

# Amitsur Algebra: Evan DeCorte, "The spectral method for geometric colouring problems"

12:00pm to 1:00pm

## Location:

Manchester Building, Room 209
Title: The spectral method for geometric colouring problems
2017 Jun 29

12:00pm to 1:00pm

## Location:

Manchester 209
Title: Stability patterns in representation theory and applications Abstract: Many natural sequences of objects come equipped with group actions, e.g. the symmetric group on n letters acting on a space X_n. This leads to fundamental instability of invariants, such as homology, arising from the representation theory of the sequence of groups. Representation stability is a new and increasingly important set of ideas that describe a sense in which such sequence of representations (of different groups) stabilizes.
2015 Nov 19

# Groups & dynamics: Lei Yang (HUJI) "Equidistribution of expanding translates of curves in homogeneous spaces and Diophantine approximation"

10:00am to 11:00am

## Location:

Ross 70
Title: Equidistribution of expanding translates of curves in homogeneous spaces and Diophantine approximation. Abstract: We consider an analytic curve $\varphi: I \rightarrow \mathbb{M}(n\times m, \mathbb{R}) \hookrightarrow \mathrm{SL}(n+m, \mathbb{R})$ and embed it into some homogeneous space $G/\Gamma$, and translate it via some diagonal flow
2015 Nov 12

# Groups & dynamics: Elon Lindenstrauss (HUJI), "Rigidity of higher rank diagonalizable actions in positive characteristic"

10:00am to 11:00am

## Location:

Ross 70
Title: Rigidity of higher rank diagonalizable actions in positive characteristic
2015 Dec 29

# Dynamics lunch: Tom Gilat (HUJI): "Measure rigidity for `dense' multiplicative semigroups (following Einsiedler and Fish)"

12:00pm to 1:00pm

## Location:

Manchester building, Hebrew University of Jerusalem, (Coffee lounge)
2015 Nov 24

# Dynamics & probability: Yaar Salomon (Stonybrook) "The Danzer problem and a solution to a related problem of Gowers"

2:00pm to 3:00pm

## Location:

Manchester building, Hebrew University of Jerusalem, (Room 209)
The Danzer problem and a solution to a related problem of Gowers Is there a point set Y in R^d, and C>0, such that every convex set of volume 1 contains at least one point of Y and at most C? This discrete geometry problem was posed by Gowers in 2000, and it is a special case of an open problem posed by Danzer in 1965. I will present two proofs that answers Gowers' question with a NO. The first approach is dynamical; we introduce a dynamical system and classify its minimal subsystems. This classification in particular yields the negative answer to Gowers'
2015 Dec 15

# Dynamics & probability: Omri Solan (TAU) - Divergent trajectories in SL_3(R)/SL_3(Z)

2:00pm to 4:30pm

## Location:

Manchester building, Hebrew University of Jerusalem, 209
Abstract:
2015 Nov 03

# Dynamics lunch: Or Landesberg (HUJI)

12:00pm to 1:00pm

## Location:

Manchester building, Hebrew University of Jerusalem, (Room 209)
Title: On the Mixing Property for Hyperbolic Systems [following a paper by Martine Babillot]
2015 Dec 02

# Dynamics & probability: Ron Rosenthal (ETHZ) "Local limit theorem for certain ballistic random walks in random environments"

2:00pm to 3:00pm

## Location:

Ross 70
Title: Local limit theorem for certain ballistic random walks in random environments Abstract: We study the model of random walks in random environments in dimension four and higher under Sznitman's ballisticity condition (T'). We prove a version of a local Central Limit Theorem for the model and also the existence of an equivalent measure which is invariant with respect to the point of view of the particle. This is a joint work with Noam Berger and Moran Cohen.