2019 Jun 27

# Group and dynamics seminar: Asaf Naor (Princeton)

10:00am to 11:15am

2019 Jun 03

# Combinatorics - back to back:

11:00am to 1:00pm

## Location:

CS Rothberg bldg, room B-500, Safra campus
First talk: Speaker: Madeleine Weinstein (Berkeley) Title: Voronoi Cells of Varieties Abstract:
2019 May 13

# Combinatorics: Shira Zerbib (U. Michigan, Iowa State University) "Envy-free division of a cake without the “hungry players" assumption"

11:00am to 1:00pm

## Location:

CS bldg, room B-500, Safra campus
Speaker: Shira Zerbib (U. Michigan, Iowa State University) Title: Envy-free division of a cake without the “hungry players" assumption Abstract: The fair division theorem due to Stromquist (1980) ensures that under some conditions it is possible to divide a rectangular cake into n pieces and assign one piece to each of n players such that no player strictly prefers a piece that has not been assigned to him.
2019 May 06

# Combinatorics: Omri Ben Eliezer (TAU) "Finding patterns in permutations"

11:00am to 1:00pm

## Location:

CS building, room B-500, Safra campus
Speaker: Omri Ben Eliezer, TAU Title: Finding patterns in permutations Abstract: For two permutations sigma and pi, we say that sigma contains a copy of pi, if there is a subset (not necessarily consecutive) of elements in sigma, whose relative order is the same as in pi. For example, if pi = (1,2,3), then a copy of pi in sigma amounts to an increasing subsequence in sigma of length 3. As shown by Guillemot and Marx, a copy of a constant length pi can be found in sigma in linear time. However, how quickly can one find such a
2019 May 16

# Basic Notions: Ehud de Shalit (HUJI) " Hilbert's 12th problem - recent developments"

4:00pm to 5:15pm

## Location:

Ross 70
Hilbert's 12th problem (Kronecker's Jugendtraum) is one of the major open problems
2019 Jun 10

# Combinatorics: Eyal Karni (BIU) "Combinatorial high dimensional expanders"

11:00am to 1:00pm

## Location:

CS bldg, room B-500, Safra campus
Speaker: Eyal Karni (BIU) Title: Combinatorial high dimensional expanders Abstract: An eps-expander is a graph G=(V,E) in which every set of vertices X where |X|<=|V|/2 satisfies |E(X,X^c)|>=eps*|X| . There are many edges that "go out" from any relevant set.
2019 May 27

# Combinatorics: Uri Rabinovich (U. Haifa) TBA

11:00am to 1:00pm

2019 May 23

# Basic Notions: Ehud de Shalit (HUJI) " Hilbert's 12th problem - recent developments"

4:00pm to 5:15pm

## Location:

Ross 70
Hilbert's 12th problem (Kronecker's Jugendtraum) is one of the major open problems
2019 Jun 24

# Combinatorics: Doron Puder (TAU) TBA

11:00am to 1:00pm

2019 May 27

# NT & AG Seminar "A dream desingularization algorithm", Michael Temkin

2:30pm to 3:30pm

Abstract: Any birational geometer would agree that the best algorithm for resolution of singularities should run by defining a simple invariant of the singularity and iteratively blowing up its maximality locus. The only problem is that already the famous example of Whitney umbrella shows that this is impossible, and all methods following Hironaka had to use some history and resulted in more complicated algorithms. Nevertheless, in a recent work with Abramovich and Wlodarczyk we did construct such an algorithm, and an independent description of a similar
2019 May 21

# Landau Lecture 3: Liftings mod p2 and the Nygaard filtration

## Lecturer:

Prof. Luc Illusie (Université Paris-Sud)
1:00pm to 2:00pm

## Location:

Ross 70

### Liftings mod p2 and the Nygaard filtration

Abstract: I will revisit old results on liftings mod p2 and decompositions of de Rham complexes in positive characteristic (Deligne-I.) at the light of relations recently discovered independently by Bhargav Bhatt and myself between cotangent complexes, de Rham-Witt, and derived de Rham complexes.

2019 Jun 20

# Noam Kolodner

10:00am to 11:00am

2019 Jun 06

# Groups and dynamics seminar - Yoav Gat (Technion) - Counting lattice points on the Heisenberg groups - A generalization of a classical problem to a non-commutative setting

10:00am to 11:00am

Abstract: In this talk, I shall present a generalization of the lattice point counting problem for Euclidean balls in the context of a certain type of homogeneous groups, the so-called Heisenberg groups.
2019 Jun 13

# Group and dynamics seminar: Michael Chapman (HUJI): Cutoff on Ramanujan complexes

10:00am to 11:10am

Abstract: A Markov chain over a finite state space is said to exhibit the total variation cutoff phenomenon if, starting from some Dirac measure, the total variation distance to the stationary distribution drops abruptly from near maximal to near zero. It is conjectured that simple random walks on the family of $k$-regular, transitive graphs with a two sided $\epsilon$ spectral gap exhibit total variation cutoff (for any fixed $k$ and \$\epsilon). This is known to be true only in a small number of cases.
2019 Jun 04

2:00pm to 3:00pm