2017 May 25

# Basic notions: Ehud de Shalit - The Loxton - van der Poorten conjecture

4:00pm to 5:00pm

Abstract: Adamczewski and Bell proved in the 2013 the Loxton - van der Poorten
conjecture. It says the following. Let f be a Laurent power series (with complex
coefficients) and let \sigma_p be the operator substituting x^p for x in f. Suppose that f satisfies a homogenous polynomial equation in the operator \sigma_p with
coefficients which are rational functions, and a similar equation in the operator \sigma_q where p and q are multiplicatively independent natural numbers. Then f is a rational function.
2015 Dec 23

# Eshnav: Dorit Aharonov - "The revolution of quantum information"

Dorit Aharonov
6:00pm to 7:00pm

## Location:

Math 2 (Manchester building)
2017 Dec 13

# Eshnav: Ohad Noy Feldheim - "Lattices, Colorings and Magnets"

6:15pm to 7:15pm

## Location:

Math 2 (Manchester building)
2016 Jan 13

# Eshnav: Mike Hochman - "The Isoperimetric Inequality"

Mike Hochman
6:00pm to 7:00pm

## Location:

Math 2 (Manchester building)
2015 Dec 02

# Eshnav: Raz Kupferman - "Geometry and elasticity: from torn nylon to carnivorous plants"

Raz Kupferman
6:00pm to 7:00pm

## Location:

Math 2 (Manchester building)
2017 May 18

# Basic notions: Ehud de Shalit - The Loxton - van der Poorten conjecture

4:00pm to 5:00pm

Abstract: Adamczewski and Bell proved in the 2013 the Loxton - van der Poorten
conjecture. It says the following. Let f be a Laurent power series (with complex
coefficients) and let \sigma_p be the operator substituting x^p for x in f. Suppose that f satisfies a homogenous polynomial equation in the operator \sigma_p with
coefficients which are rational functions, and a similar equation in the operator \sigma_q where p and q are multiplicatively independent natural numbers. Then f is a rational function.
2015 Nov 11

# Eshnav: Karim Adiprasito (HUJI) "Combinatorial geometry"

6:00pm to 7:00pm

## Location:

Math 2 (Manchester building)
Title: Combinatorial Geometry
Abstract:
Matroids or (combinatorial) geometries are natural abstractions of
the concept of linear and algebraic independence over fields, were defined
by Whitney nearly a century ago. Since then, they have become a crucial tool
in model theory, graph coloring, noncommutative geometty and the study of
characteristic classes. Quite amazingly, it was recently shown that matroids
satisy deep results classically associated to algebraic varieties, something
that was not expected in this generality.
2017 Apr 30

# Combinatorics: Amir Yehudayoff (Technion) TBA

Repeats every week every Sunday until Sun Jun 25 2017 except Sun Apr 30 2017.
11:00am to 1:00pm

11:00am to 1:00pm
11:00am to 1:00pm
11:00am to 1:00pm
11:00am to 1:00pm
11:00am to 1:00pm
11:00am to 1:00pm
11:00am to 1:00pm
11:00am to 1:00pm

## Location:

Rothberg B221 (CS building)
Speaker: Misha Tyomkyn (TAU)
Title: Lagrangians of hypergraphs and the Frankl-Furedi conjecture
Abstract:
Frankl and Furedi conjectured in 1989 that the maximum Lagrangian of
all r-uniform hypergraphs of given size m is realised by the initial
segment of the colexicographic order. For r=3 this was partially solved
by Talbot, but for r\geq 4 the conjecture was widely open. We verify
the conjecture for all r\geq 4, whenever
$\binom{t-1}{r} \leq m \leq \binom{t}{r}- \gamma_r t^{r-2}$
2015 Dec 24

# Amitsur Algebra: Michael Larsen (Indiana U)

12:00pm to 1:15pm

## Location:

Manchester Building (room 209), Jerusalem, Israel
Title: Character values on compact simple Lie groups
Abstract: This work is part of a joint project with Aner and others to find upper bounds for values of irreducible characters in two related settings: compact simple Lie groups and finite groups of Lie type. I will discuss the first case, presenting bounds of the form
$$|\chi(g)| = O(\chi(1)^\alpha),$$
2015 Nov 19

# Amitsur Algebra: Avinoam Mann (HUJI), "Irreducible characters of some p-groups"

12:00pm to 1:15pm

## Location:

Manchester Building (room 209), Jerusalem, Israel
Abstract: We will discuss the characters of some classes of finite p-groups, in particular groups of maximal class and generalizations, and normally monomial groups.
2016 Jan 14

# Amitsur Algebra: Frauke Bleher (U of Iowa): Holomorphic differentials in positive characteristic

12:00pm to 1:15pm

## Location:

Manchester Building (room 209), Jerusalem, Israel
Title: Holomorphic differentials in positive characteristic
Abstract: This talk is about joint work with Ted Chinburg and Aristides Kontogeorgis.
Let X be a smooth projective curve over an algebraically closed field
k of positive characteristic p. Suppose G is a finite group with non-trivial
2015 Dec 03

# Amitsur Algebra: Boris Plotkin (Hebrew U)

12:00pm to 1:15pm

## Location:

Manchester Building (room 209), Jerusalem, Israel
Title: Algebraic Geometry in an arbitrary variety of algebras and Algebraic Logic
Abstract: I will speak about a system of notions which lead to interesting new problems for groups and algebras as well as to reinterpretation of some old ones.
2016 Mar 08

# Dynamics & probability: Elon Lindenstrauss (Mean dimension and embedding of Z^d actions)

2:00pm to 3:00pm

## Location:

Manchester building, Hebrew University of Jerusalem, (Room 209)
2016 Mar 29

# Dynamics & probability: Paul Nelson (ETH) - Microlocal lifts and quantum unique ergodicity on GL(2,Q_p)

2:00pm to 3:00pm

## Location:

Manchester building, Hebrew University of Jerusalem, (Room 209)
Abstract:
There are by now several celebrated measure classification results to the effect that a measure is uniform provided it possesses sufficient "invariance" as quantified by stabilizer, entropy, or recurrence. In some applications, part of the challenge is to identify or construct measures to which these hypotheses apply.
2018 Jan 15

# Michael Farber: "Robot motion planning and equivariant Bredon cohomology"

9:00am to 11:00am

## Location:

IIAS, Feldman Building, Givat Ram

Abstract: The motion planning problem of robotics leads to an interesting invariant of topological spaces, TC(X), depending on the homotopy type of X = the configuration space of the system. TC(X) is an integer reflecting the complexity of motion planning algorithms for all systems (robots) having X as their configuration space. Methods of algebraic topology allow to compute or to estimate TC(X) in many examples of practical interest. In the case when the space X is aspherical the number TC(X) depends only on the fundamental group of X.