• 2019 Jan 01

# Dynamics Lunch: Zemer Kosloff: On the action of the permutation group on the cantor set (after Aldous-Pitman and Stratila-Voiculescu)

12:00pm to 1:00pm

• 2018 Dec 18

# Dynamics Lunch: Omer Ben-Neria "Dichotomies for Borel equivalence relations"

12:00pm to 1:00pm

Abstract: We would like present several results in descriptive set theory involving definable equivalence relations on Polish spaces. Given an equivalence relation E on a polish space X, we would like to study the classification problem of determining whether two objects x,y in X are E-related.
• 2018 Dec 11

# Dynamics Lunch: Tom Gilat "A proof of the Erdos-Kac theorem by A. Granville and K. Soundararjan"

12:00pm to 1:00pm

## Location:

Manchester faculty club
• 2018 Dec 04

# Dynamics Lunch: Manuel Luethi "Well approximable numbers and times n invariant probability measures on the torus after Einsiedler, Fishman and Shapira."

12:00pm to 1:00pm

## Location:

Manchester faculty club
• 2018 Nov 27

# Dynamics Seminar: Yan Dolinsky

12:00pm to 1:00pm

## Location:

Manchester faculty club
• 2018 Nov 20

# Dynamics Lunch: Jiange Li "Sumsets and entropy" after Ruzsa

12:00pm to 1:00pm

## Location:

Manchester faculty club
• 2018 Nov 13

# Dynamics Lunch: Jakub Konieczny "Sarnak conjecture and automatic sequences (following C. Müllner and M. Lemańczyk)"

12:00pm to 1:00pm

## Location:

Manchester faculty club
• 2018 Nov 06

# Dynamics Lunch: Weikun He "Counterexamples to a conjecture of Woods, after Regev, Shapira and Weiss."

12:00pm to 1:00pm

## Location:

Manchester faculty club
• 2018 Oct 23

# Dynamics Lunch: Amir Algom "On \alpha \beta sets."

12:00pm to 1:00pm

## Location:

Manchester faculty club
Let $\alpha, \beta$ be elements of infinite order in the circle group. A closed set K in the circle is called an \alpha \beta set if for every x\in K either x+\alpha \in K or x+\beta \in K. In 1979 Katznelson proved that there exist non-dense \alpha \beta sets, and that there exist \alpha \beta sets of arbitrarily small Hausdorff dimension. We shall discuss this result, and a more recent result of Feng and Xiong, showing that the lower box dimension of every \alpha \beta set is at least 1/2.
• 2018 Jun 26

# Dynamics Lunch: Jasmin Matz (Huji) ״Distribution of periodic orbits of the horocycle flow״

12:00pm to 1:00pm

## Location:

Manchester lounge
An old result of Hedlund tells us that there are no closed orbits for the horocycle flow on a compact Riemann surface M. The situation is different if M is non-compact in which case there is a one-parameter family of periodic orbits for every cusp of M. I want to talk about a result by Sarnak concerning the distribution of the such orbits in each of these families when their length goes to infinity. It turns out that these orbits become equidistributed in M and the rate of convergence can in fact be quantified in terms of spectral properties of the Eisenstein series on M.