2018 Oct 15

# NT & AG Lunch: Yakov Varshavsky "Mathematics around Langlands program"

1:00pm to 2:00pm

## Location:

Faculty lounge, Math building

This is a new seminar, whose official name is "Topics in number theory
and algebraic geometry". At least in the beginning the goal
of the seminar will be to give a (relatively) gentle introduction to
various topics, which should be accessible to beginning but motivated graduate students.
The seminar has a number in the shnaton (80942), so graduate students
can get a credit for it.
First talk: The goal of this organizational/introductory talk will be to
describe areas of mathematics, connected to Langlands program.
2018 Dec 09

# Kazhdan seminar: Tomer Schlank "The Nonabelian Chabauty Method"

12:00pm to 2:00pm

## Location:

Ross 70A
Abstract: The Chabauty method is a remarkable tool which employs p-adic analitic methods (in particular Colman integration.) To study rational points on curves. However the method can be applied only when the genus of the curve in question is larger than its Mordell-Weil rank. Kim developed a sophisticated "nonableian" generalisation. We shall present the classical methid, and give an approachable introduction to Kim's method. I'm basically going to follow http://math.mit.edu/nt/old/stage_s18.html
2018 Oct 08

# T&G: Stephan Rosebrock (Karlsruhe), Asphericity, Relative Asphericity and Labelled Oriented Trees

12:30pm to 2:00pm

## Location:

Room 70, Ross Building, Jerusalem, Israel
The Whitehead conjecture asks whether a subcomplex of an aspherical 2-complex is always aspherical. This question is open since 1941. Howie has shown that the existence of a finite counterexample implies (up to the Andrews-Curtis conjecture) the existence of a counterexample within the class of labelled oriented trees. Labelled oriented trees are algebraic generalisations of Wirtinger presentations of knot groups.
2018 Nov 18

# Special Analysis Seminar: Sergey Denisov (Wisconsin) "Szego theorem for measures on the real line: optimal results and applications"

12:00pm to 1:00pm

## Location:

Manchester building, room 209
Title: Szego theorem for measures on the real line: optimal results and applications. Abstract: Measures on the unit circle for which the logarithmic integral converges can be characterized in many different ways: e.g., through their Schur parameters or through the predictability of the future from the past in Gaussian stationary stochastic process. In this talk, we consider measures on the real line for which logarithmic integral exists and give their complete characterization in terms of the Hamiltonian in De Branges canonical system. This provides a generalization of the
2019 Jan 07

# Combinatorics: Bruno Benedetti (U. Miami) "Local constructions of manifolds"

11:00am to 1:00pm

## Location:

CS building, room B500, Safra campus, Givat Ram
Speaker: Bruno Benedetti, U. Miami Title: Local constructions of manifolds Abstract: Starting with a tree of tetrahedra, say you are allowed to recursively glue together some two boundary triangles that have nonempty intersection. You may perform this type of move as many times you want. Let us call "Mogami manifolds" the triangulated 3-manifolds (with or without boundary) that can be obtained this way. Mogami, a quantum physicist, conjectured in 1995 that all triangulated 3-balls are Mogami. This conjecture implies an important one in discrete quantum gravity
2018 Nov 05

# Combinatorics: Ohad Klein, BIU, "Biased halfspaces, noise sensitivity, and local Chernoff inequalities"

11:00am to 1:00pm

## Location:

Rothberg CS bldg, room B500, Safra campus, Givat Ram
Speaker: Ohad Klein, BIU Title: Biased halfspaces, noise sensitivity, and local Chernoff inequalities Abstract: Let X be a random variable defined by X=\sum_i a_i x_i where x_i are independent random variables uniformly distributed in \{-1, 1\}, and a_i in R, the reals. Assume Var(X)=1=sum a_{i}^2. We investigate the tail behavior of the variable X, and apply the results to study halfspace functions f:{-1,1}^{n}-->{-1,1} defined by f(x)=1 (\sum_i a_i x_i > t) for some t in R. A puzzle: Let a = max_{i} |a_{i}|. Is it true that Pr[|X| \leq a] \geq a/10?
2018 Oct 22

# Combinatorics: Spencer Backman, HU, "Cone valuations, Gram's relation, and flag-angles"

11:00am to 1:00pm

## Location:

Rothberg CS building, room B500, Safra campus, Givat Ram
Speaker: Spencer Backman, HU Title: Cone valuations, Gram's relation, and flag-angles
2018 Dec 10

# Erdos lecture I: Counting linear extensions and Young tableaux

## Lecturer:

Igor Pak (UCLA)
11:00am to 1:00pm

## Location:

IIAS, lecture hall 130, Safra campus, Givat Ram
Speaker: Igor Pak, UCLA Title: Counting linear extensions. Abstract: I will survey various known and recent results on counting the number of linear extensions of finite posets. I will emphasize the asymptotic and complexity aspects for special families, where the problem is especially elegant yet remains #P-complete. In the second half of the talk I will turn to posets corresponding to (skew) Young diagrams. This special case is important for many applications in representation theory and algebraic geometry.
2018 Oct 29

# Combinatorics: Noam Lifshitz, BIU, "Sharp thresholds for sparse functions with applications to extremal combinatorics."

11:00am to 1:00pm

## Location:

Rothberg CS blgd, room B500, Safra campus, Givat, Ram
Speaker: Noam Lifshitz, BIU Title: Sharp thresholds for sparse functions with applications to extremal combinatorics. Abstract: The sharp threshold phenomenon is a central topic of research in the analysis of Boolean functions. Here, one aims to give sufficient conditions for a monotone Boolean function $f$ to satisfy $\mu_{p}(f)=o(\mu_{q}(f))$, where $q = p + o(p)$, and $\mu_{p}(f)$ is the probability that $f=1$ on an input with independent coordinates, each taking the value $1$ with probability $p$.
2018 Oct 15

# Combinatorics: Tammy Ziegler, HU, "Extending weakly polynomial functions from high rank varieties"

11:00am to 1:00pm

## Location:

Rothberg CS building, room B500, Safra campus, Givat Ram
Speaker: Tammy Ziegler, HU Title: Extending weakly polynomial functions from high rank varieties Abstract: Let k be a field, V a k-vector space, X in V a subset. Say that f: X —> k is weakly polynomial of degree a if its restriction to any isotropic subspace is a polynomial degree of a. We show that if X is a high rank variety then any weakly polynomial function of degree a is the restriction to X of a polynomial of degree a on V. Joint work with D. Kazhdan.
2018 Dec 19

# Analysis Seminar: Dmitry Ryabogin (Kent) "On a local version of the fifth Busemann-Petty Problem"

12:00pm to 1:00pm

## Location:

Ross Building, Room 70
Title: On a local version of the fifth Busemann-Petty Problem Abstract: In 1956, Busemann and Petty posed a series of questions about symmetric convex bodies, of which only the first one has been solved. Their fifth problem asks the following. Let K be an origin symmetric convex body in the n-dimensional Euclidean space and let H_x be a hyperplane passing through the origin orthogonal to a unit direction x. Consider a hyperplane G parallel to H_x and supporting to K and let C(K,x)=vol(K\cap H_x)dist (0, G).
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
2019 Apr 10

# Analysis Seminar: Gregory Berkolaiko (Texas)

12:00pm to 1:00pm

2019 Mar 27

# Analysis Seminar: Ofer Zeitouni (Weizmann))

12:00pm to 1:00pm

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