Seminars

2019 Feb 20

Analysis Seminar: Itay Londner (UBC) "Interpolation sets and arithmetic progressions"

12:00pm to 1:00pm

Location: 

Ross 70
Title: Interpolation sets and arithmetic progressions Abstract: Given a set S of positive measure on the unit circle, a set of integers K is an interpolation set (IS) for S if for any data {c(k)} in l^2(K) there exists a function f in L^2(S) such that its Fourier coefficients satisfy f^(k)=c(k) for all k in K. In the talk I will discuss the relationship between the concept of IS and the existence arithmetic structure in the set K, I will focus primarily on the case where K contains arbitrarily long arithmetic progressions with specified lengths and step sizes.
2019 Jan 01

Yotam Smilansky (HUJI), Multiscale substitution schemes and Kakutani sequences of partitions.

2:15pm to 3:15pm

Location: 

Ross 70
Abstract: Substitution schemes provide a classical method for constructing tilings of Euclidean space. Allowing multiple scales in the scheme, we introduce a rich family of sequences of tile partitions generated by the substitution rule, which include the sequence of partitions of the unit interval considered by Kakutani as a special case. In this talk we will use new path counting results for directed weighted graphs to show that such sequences of partitions are uniformly distributed, thus extending Kakutani's original result. Furthermore, we will describe certain limiting frequencies
2018 Dec 27

Basic Notions: Sergiu Hart - "Game Dynamics and Equilibria"

4:00pm to 5:00pm

Location: 

Ross 70
The general theme is game dynamics leading to equilibrium concepts. The plan is to deal with the following topics (all concepts will be defined, and proofs / proof outlines will be provided): (1) An integral approach to the construction of calibrated forecasts and their use for Nash equilibrium dynamics. (2) Blackwell's Approachability Theorem and its use for correlated equilibrium dynamics (regret-matching). (3) Communication complexity and its use for the speed of convergence of uncoupled dynamics.
2019 Jan 03

Basic Notions: Dorit Aharonov - "Quantum computation"

4:00pm to 5:00pm

Location: 

Ross 70
Quantum computation ================== You can hardly open the newspaper nowadays without seeing something about Quantum computation. But aside from the hype and the industry interest, this deceivingly simple model offers a surprisingly rich set of mathematical, physical and conceptual questions, which seem to touch upon almost any area of mathematics: from group representations, to Markov chains, Knot invariants, expanders, cryptography, lattices, differential geometry, and many more. I will give some definitions, provide some basic results, and sketch some open problems.
2019 Mar 20

Analysis Seminar: Andrei Osipov (Yale) "On the evaluation of sums of periodic Gaussians"

12:00pm to 1:00pm

Location: 

Ross 70
Title: On the evaluation of sums of periodic Gaussians Abstract: Discrete sums of the form $\sum_{k=1}^N q_k \cdot \exp\left( -\frac{t – s_k}{2 \cdot \sigma^2} \right)$ where $\sigma>0$ and $q_1, \dots, q_N$ are real numbers and $s_1, \dots, s_N$ and $t$ are vectors in $R^d$, are frequently encountered in numerical computations across a variety of fields. We describe an algorithm for the evaluation of such sums under periodic boundary conditions, provide a rigorous error analysis, and discuss its implications on the computational cost and choice of parameters.
2018 Dec 25

T&G: Or Hershkovits (Stanford), Mean Curvature Flow of Surfaces -- NOTE special time and location

1:00pm to 2:00pm

Location: 

Room 70, Ross Building, Jerusalem, Israel
In the last 35 years, geometric flows have proven to be a powerful tool in geometry and topology. The Mean Curvature Flow is, in many ways, the most natural flow for surfaces in Euclidean space. In this talk, which will assume no prior knowledge, I will illustrate how mean curvature flow could be used to address geometric questions.
2019 Jan 11

Joram Seminar: Lev Buhovski (Tel-Aviv University) - 0,01% Improvement of the Liouville property for discrete harmonic functions on Z^2.

11:45am to 12:45pm

Location: 

Manchester Building (Hall 2), Hebrew University Jerusalem
Let u be a harmonic function on the plane. The Liouville theorem claims that if |u| is bounded on the whole plane, then u is identically constant. It appears that if u is a harmonic function on the lattice Z^2, and |u| < 1 on 99,99% of Z^2, then u is a constant function. Based on a joint work with A. Logunov, Eu. Malinnikova and M. Sodin.

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