2017
Dec
11

# Combinatorics seminar: Leonard Schulman

11:00am to 12:30pm

## Location:

Eilat Hall at IIAS

Title: The Invisible Hand of Laplace Read more about Combinatorics seminar: Leonard Schulman

2017
Dec
11

11:00am to 12:30pm

Eilat Hall at IIAS

Title: The Invisible Hand of Laplace Read more about Combinatorics seminar: Leonard Schulman

2016
Dec
19

11:00am to 1:00pm

Rothberg B220 (CS)

Speaker: Lukas Kühne (University of Bonn)
Title: Heavy hyperplanes in multiarrangements and their freeness
Abstract:
One of the central topics among the theory of hyperplane arrangements is their freeness. Terao's conjecture tries to link the freeness with the combinatorics of an arrangement. One of the few categories of arrangements which satisfy this conjecture consists of 3-dimensional arrangements with an unbalanced Ziegler restriction. This means that the arrangement contains a lot of hyperplanes intersecting in one single line

2016
Feb
29

Repeats every week every Monday until Mon Jun 13 2016 .

10:30am to 12:30pm10:30am to 12:30pm

10:30am to 12:30pm

10:30am to 12:30pm

10:30am to 12:30pm

10:30am to 12:30pm

10:30am to 12:30pm

10:30am to 12:30pm

10:30am to 12:30pm

10:30am to 12:30pm

10:30am to 12:30pm

10:30am to 12:30pm

10:30am to 12:30pm

10:30am to 12:30pm

10:30am to 12:30pm

10:30am to 12:30pm

B220 Rothberg (CS and Engineering building)

NOTE THE SPECIAL TIME: 11:00--12:30
Speaker: Eyal Ackerman, University of Haifa at Oranim
Title: Coloring points with respect to squares
Abstract:
Is there an absolute constant $m$ such that any finite planar point set can be 2-colored such that every axis-parallel square that contains at least $m$ points contains points of both colors? I will discuss this problem and related ones.

2017
Nov
20

11:00am to 12:30pm

IIAS Room 130

Speaker 1: Sria Louis
Title: Asymptotically Almost Every 2r-regular Graph has an Internal Partition
Abstract: An internal partition of a graph is a partitioning of the vertex set into two parts such that for every vertex, at least half of its neighbors are on its side. It is easy to notice that such a partition doesn't always exist (e.g. - cliques), though, both the existence and finding of such a partition - are open problems.
Stiebitz (1996), responding to a problem of Thomassen (1983), made a breakthrough in this area, but the question and some interesting generalizations are still open.

2017
Mar
06

11:00am to 1:00pm

Rothberg B220 (CS)

Speaker: Zilin Jiang (Technion)
Title: Relations between Tverberg points and central points
Abstract:
Given 3n lines in general position in the plane, it is always possible to partition them into n triples of lines so that all the triangles, formed by the triples, share a common point. This result is known back in 1988 by J.P. Roudneff. Strangely, in higher dimensions, it is only proved by Roman Karasev for n that is a prime power.

2018
Mar
26

2016
Dec
05

11:00am to 1:00pm

B220 Rothberg (CS)

Speaker: Klim Efremenko (TAU)
Title: Testing Equality in Communication Graphs
Abstract:
Let G=(V,E) be a connected undirected graph with k vertices. Suppose
that on each vertex of the graph there is a player having an n-bit
string. Each player is allowed to communicate with its neighbors
according to a (static) agreed communication protocol and the players
must decide, deterministically, if their inputs are all equal. What
is the minimum possible total number of bits transmitted in a protocol
solving this problem? We determine this minimum up to a lower order

2017
Dec
25

11:00am to 12:30pm

Room 130 at the IIAS

Title: Trace reconstruction for the deletion channel

2017
Jan
23

11:00am to 1:00pm

Rothberg B220 (CS bldg)

Speaker: Elchanan Mossel (MIT)
Title: Lower Bounds on Same-Set Inner Product in Correlated Spaces
Abstract: Suppose we pick X uniformly from {0,1,2}^n and Y is picked by letting each Y(i) = X(i) or
X(i) + 1 mod 3 with probability 0.5 each independently.
Is it true that for every set S with |S| > c 2^n it holds that the probability that both X and Y are in S is at least g(c) > 0, where g does not depend on the dimension n?
Similar questions were asked before in different contexts. For example,

2017
May
29

11:00am to 1:00pm

Rothberg B220 (CS bldg)

Speaker: Dmitry Faifman (U Toronto)
Title: The integral geometry of indefinite signature.

2016
Nov
21

11:00am to 1:00pm

B220 Rothberg (CS)

Speaker: David Ellis, Queen Mary
Title: Some applications of the $p$-biased measure to Erd\H{o}s-Ko-Rado type problems
Abstract:

2018
Jan
08

11:00am to 12:30pm

Eilat Hall at IIAS

There are exponentially many triangulations of a fixed manifold extremely distant from each other in some natural metric. I will discuss similar results for contractible 2-complexes. In order to prove these for the manifold being the sphere (or a contractible complex) one needs to create topology out of nothing. This is done by studying group theory of the trivial group.

2017
Jan
09

11:00am to 1:00pm

Rothberg B220 (CS bldg)

Speaker: Ilan Karpas, HU
Tilte: Families with forbidden intersection patterns
Abstract:
Let l, n be even natural numbers. A pattern p of length l is an element
p = (p1, . . . , pl) ∈ {−, +}^l. Given such a pattern and two sets A, B ⊂ [n], we say that the pair (A, B) forms pattern p if the following conditions are satisfied:
1. A \Delta B = {i_1, . . . , i_l}, where i_1 < i_2 < . . . < i_l,
2. For 1 ≤ j ≤ l, we have i_ j ∈ A \ B if p_ j = + and i_ j ∈ B \ A if p_ j = −.

2016
Nov
07

10:40am to 12:50pm

Israel Institute for Advanced Studies, Safra campus, Givat Ram

* This talk is joint with the 20th Midrasha Mathematicae: 60 faces to groups, celebrating Alex Lubotzky's 60th birthday.
The full program for AlexFest, Nov. 6--11, is detailed here:
http://www.as.huji.ac.il/ias/public/121/the20thMidrashaMa2016/program.pdf
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Speaker: László Babai (University of Chicago)
Title: Finite permutation groups and the Graph Isomorphism problem
Updated abstract:
The Graph Isomorphism (GI) problem is the algorithmic problem

2018
Jan
01

11:00am to 12:30pm