2016
Nov
20

# Zabrodsky Lectures: Dan Freed (University of Texas)

Sun, 20/11/2016 (All day) to Thu, 24/11/2016 (All day)

HOME / Eventss

2016
Nov
20

Sun, 20/11/2016 (All day) to Thu, 24/11/2016 (All day)

2018
Apr
26

2018
Apr
26

Thu, 26/04/2018 (All day) to Tue, 01/05/2018 (All day)

2018
May
23

4:15pm to 5:15pm

Manchester Building (Hall 2), Hebrew University Jerusalem

The Crossing Lemma of Ajtai, Chvátal, Newborn, Szemerédi (1982) and Leighton (1983 )states that if a graph of n vertices and e>4n edges is drawn in the plane, then the number of crossings between its edges must be at least constant times e^3/n^2. This statement, which is asymptotically tight, has found many applications in combinatorial geometry and in additive combinatorics. However, most results that were obtained using the Crossing Lemma do not appear to be optimal, and there is a quest for improved versions of the lemma for graphs satisfying certain special properties.

2018
Apr
09

2018
Mar
28

12:00pm to 1:00pm

2018
Jun
06

12:00pm to 1:00pm

Ross Building, Room 70

Abstract:
Hamiltonian impact systems are dynamical systems in which there are two main mechanisms which dictate the system’s behavior - Hamilton’s equations which govern the motion inside the impact system domain, and the billiard reflection rule which governs the motion upon reaching the domain boundary. As the dynamics in impact systems are piecewise smooth by nature due to the
collisions with the boundary, many of the traditional tools used in the analysis of Hamiltonian
systems cannot be applied to impact systems in a straightforward manner. This talk will present a

2018
May
02

12:00pm to 1:00pm

room 70, Ross Building

Abstract: We will discuss connections between Gromov's work on isoperimetry of waists and Milman's work on the M-ellipsoid of a convex body. It is proven that any convex body K in an n-dimensional Euclidean space has a linear image K_1 of volume one satisfying the following waist inequality: Any continuous map f from K_1 to R^d has a fiber f^{-1}(t) whose (n-d)-dimensional volume is at least c^{n-d}, where c > 0 is a universal constant. Already in the case where f is linear, this constitutes a slight improvement over known results.

2018
Feb
05

2018
Feb
26

(All day)

Room 130, IIAS, Feldman Building, Givat Ram

10:00-11:00:

11:30-12:30:

14:00-16:00:

2018
Jan
31

2018
Jun
21

2:30pm to 3:30pm

Manchester Building (Hall 2), Hebrew University Jerusalem

Given a convex polytope P, what is the number of integer points in P? This problem is of great interest in combinatorics and discrete geometry, with many important applications ranging from integer programming to statistics. From a computational point of view it is hopeless in any dimensions, as the knapsack problem is a special case. Perhaps surprisingly, in bounded dimension the problem becomes tractable. How far can one go? Can one count points in projections of P, finite intersections of such projections, etc.?

2016
Jun
09

12:00pm to 1:15pm

Manchester Building (Ross 63), Jerusalem, Israel

*** Please note the LOCATION ***
We shall give a simple generalization of commutative rings. The
category GR of such generalized rings contains ordinary commutative
rings (fully, faithfully), but also the "integers" and the "residue
field" at a real or complex place of a number field ; the "field with
one element" F1 (the initial object of GR) ; the "Arithmetical
Surface" (the categorical sum of the integers Z with them self). We
shall show this geometry sees the real and complex places of a number
field K : the valuation sub GR of K correspond to the finite and

2018
Jan
25