Eventss

2019 Apr 01

Combinatorics: Raphy Yuster (U. Haifa) "On some Ramsey type problems in tournaments"

11:00am to 1:00pm

Location: 

CS B-500, Safra campus
Speaker: Raphy Yuster, U. Haifa
Title: On some Ramsey type problems in tournaments
Abstract:
I will talk about several Ramsey type problems in tournaments guaranteeing the existence of subgraphs with certain chromatic properties.
Here are two such problems which attracted some attention recently:
1. Let g(n) be the smallest integer such that every tournament with more than g(n) vertices has an *acyclic subgraph* with chromatic number larger than n.
2019 Jun 17

NO seminar: mini conference in memory of Prof. Yossi Zaks at U. Haifa

11:00am to 1:00pm

Location: 

U. Haifa

From Raphy Yuster: On Monday 17 June, 2019 we will hold a one day mini conference in memory of Professor Yossi Zaks
(see attached poster or updated information in
http://sciences.haifa.ac.il/math/wp/?page_id=1382 )
Mini conference: Yossi Zaks Memorial Meeting – Monday, June 17, 2019
list of speakers
Noga Alon, Princeton University and Tel Aviv University
Gil Kalai, Hebrew University
Nati Linial, Hebrew University
Rom Pinchasi, The Technion
Organizers
2019 Apr 29

Combinatoric: Karthik C. Srikanta (Weizmann Institute) "On Closest Pair Problem and Contact Dimension of a Graph"

11:00am to 1:00pm

Location: 

CS B-500, Safra campus
Speaker: Karthik C. Srikanta (Weizmann Institute)
Title: On Closest Pair Problem and Contact Dimension of a Graph
Abstract: Given a set of points in a metric space, the Closest Pair problem asks to find a pair of distinct points in the set with the smallest distance. In this talk, we address the fine-grained complexity of this problem which has been of recent interest. At the heart of all our proofs is the construction of a family of dense bipartite graphs with special embedding properties and are inspired by the construction of locally dense codes.
2019 Apr 08

Combinatorics: Kim Minki (Technion) "The fractional Helly properties for families of non-empty sets"

11:00am to 1:00pm

Location: 

CS B-500, Safra campus
Speaker: Kim Minki, Technion
Title: The fractional Helly properties for families of non-empty sets
Abstract:
Let $F$ be a (possibly infinite) family of non-empty sets.
The Helly number of $F$ is defined as the greatest integer $m = h(F)$ for which there exists a finite subfamily $F'$ of cardinality $m$ such that every proper subfamily of $F'$ is intersecing and $F'$ itself is not intersecting.
For example, Helly's theorem asserts that the family of all convex sets in $d$-dimensional Euclidean space has Helly number $d+1$.
2019 Mar 07

Emmanuel Roy (Paris 13) Non-singular Poisson suspensions

2:45pm to 3:45pm

Location: 

Ross 70
Poisson suspensions are random sets of points endowed with a transformation that displaces each point according to a single transformation of the sigma-finite space where the points lie. In this ongoing work, instead of dealing with measure-preserving transformations (which is the classical case), we are going to present our attempt to explore the non-singular case. The difficulties are counterbalanced by new tools that are trivial in the measure-preserving case but highly informative in the non-singular one.
2019 Mar 10

Ari Shnidman "Geometric expressions for derivatives of L-functions of automorphic forms" (after Yun and Zhang)

Repeats every week every Sunday until Sun Jun 23 2019 except Sun Apr 21 2019.
2:00pm to 4:00pm

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Yun and Zhang compute the Taylor series expansion of an automorphic L-function over a function field, in terms of intersection pairings of certain algebraic cycles on the so-called moduli stack of shtukas. This generalizes the Waldspurger and Gross-Zagier formulas, which concern the first two coefficients.
2019 Mar 10

Zlil Sela and Alex Lubotzky "Model theory of groups"

Repeats every week every Sunday until Sat Jun 29 2019 except Sun Apr 21 2019.
11:00am to 1:00pm

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Zlil Sela and Alex Lubotzky "Model theory of groups"
In the first part of the course we will present some of the main results in the theory of free,
hyperbolic and related groups, many of which appear as lattices in rank one simple Lie groups
We will present some of the main objects that are used in studying the theory of these groups,
and at least sketch the proofs of some of the main theorems.
In the second part of the course, we will talk about the model theory of lattices in high rank simple Lie groups.
2019 Apr 10

Set Theory Seminar - Yair Hayut (KGRC) - Partial Strong Compactness

2:00pm to 3:30pm

Location: 

Ross 63

Abstract: The ultrafilter lemma, saying that every filter can be extended to an ultrafilter, is one of the fundamental consequences of the axiom of choice. By adding closure assumptions, and asking for extension of $\kappa$-complete filters to $\kappa$-complete ultrafilters, we obtain the notion of strongly compact cardinal, which has a very high consistency strength. 

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