Seminars

2018 Jun 19

Dynamics Lunch: Amichai Lampert (Huji) "Equidistribution of Zeros of Polynomials"

12:00pm to 1:00pm

Location: 

Manchester lounge
A classical theorem of Erdos and Turan states that if a monic polynomial has small values on the unit circle (relative to its constant coefficient), then its zeros cluster near the unit circle and are close to being equidistributed in angle. In February 2018, K. Soundararajan gave a short and elementary proof of their result using Fourier analysis. I'll present this new proof.
2018 May 01

Dynamics Lunch: Ofir David (Huji) "On Minkowski's conjecture"

12:00pm to 1:00pm

Location: 

Manchester lounge
One of the first algorithm any mathematician learns about is the Euclidean division algorithm for the rational integer ring Z. When asking whether other integer rings have similar such division algorithms, we are then led naturally to a geometric interpretation of this algorithm which concerns lattices and their (multiplicative) covering radius.
2018 Apr 11

Analysis Seminar: Cy Maor (Toronto) "The geodesic distance on diffeomorphism groups"

12:00pm to 1:00pm

Location: 

Ross Building, Room 70
Since the seminal work of Arnold on the Euler equations (1966), many equations in hydrodynamics were shown to be geodesic equations of diffeomorphism groups of manifolds, with respect to various Sobolev norms. This led to new ways to study these PDEs, and also initiated the study of of the geometry of those groups as (infinite dimensional) Riemannian manifolds.
2018 May 14

Combinatorics: Joel Friedman (UBC) "Open Problems Related to the Zeta Functions"

11:00am to 12:30pm

Location: 

IIAS, Eilat hall, Feldman bldg, Givat Ram
Speaker: Joel Friedman, UBC Title: Open Problems Related to the Zeta Functions Abstract: We express some open problems in graph theory in terms of Ihara graph zeta functions, or, equivalently, non-backtracking matrices of graphs. We focus on "expanders" and random regular graphs, but touch on some seemingly unrelated problems encoded in zeta functions. We suggest that zeta functions of sheaves on graphs may have relevance to complexity theory and to questions of Stark and Terras regarding whether coverings of a fixed graph can ramify like number field extensions.
2018 May 07

Combinatorics: Zur Luria (ETH), "New bounds for the n-queen's problem"

11:00am to 12:30pm

Location: 

IIAS, Eilat hall, Feldman bldg, Givat Ram
Speaker: Zur Luria, ETH Title: New bounds for the n-queen's problem Abstract: The famous n-queens problem asks: In how many ways can n nonattacking queens be placed on an n by n chessboard? This question also makes sense on the toroidal chessboard, in which opposite sides of the board are identified. In this setting, the n-queens problem counts the number of perfect matchings in a certain regular hypergraph. We give an extremely general bound for such counting problems, which include Sudoku squares and designs.
2018 Apr 24

T&G: Anton Khoroshkin (HSE), Compactified moduli spaces of rational curves with marked points as homotopy quotients of operads

1:00pm to 2:30pm

Location: 

Room 63, Ross Building, Jerusalem, Israel
I will explain the notion of a homotopy quotient of an operad providing different examples of operads of compactified moduli spaces of genus zero curves with marked points: including the space of complex curves (math.arXiv:1206.3749), the real loci of the complex one (arXiv:math/0507514) and the noncommutative …
2018 Apr 10

T&G: Jesse Kass (University of South Carolina), How to count lines on a cubic surface arithmetically

1:00pm to 2:30pm

Location: 

Room 110, Manchester Building, Jerusalem, Israel

Salmon and Cayley proved the celebrated 19th century result that a smooth cubic surface over the complex numbers contains exactly 27 lines.  By contrast, the count over the real numbers depends on the surface, and these possible counts were classified by Segre.  A number of researchers have recently made the striking observation that Segre’s work shows a certain signed count is always 3.  In my talk, I will explain how to extend this result to an arbitrary field.

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