2016
May
31

# Dynamics lunch: Yuri Kifer (HUJI) - On Erdos-Renyi law of large numbers and its extensions

12:00pm to 1:00pm

## Location:

Manchester building, Hebrew University of Jerusalem, (Coffee lounge)

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2016
May
31

12:00pm to 1:00pm

Manchester building, Hebrew University of Jerusalem, (Coffee lounge)

2016
May
10

12:00pm to 1:00pm

Manchester building, Hebrew University of Jerusalem, (Coffee lounge)

2016
Mar
22

2015
Dec
29

12:00pm to 1:00pm

Manchester building, Hebrew University of Jerusalem, (Coffee lounge)

2016
Jun
21

12:00pm to 1:00pm

Manchester building, Hebrew University of Jerusalem, (Coffee lounge)

2016
Feb
24

11:00am to 12:45pm

Ross building, Hebrew University (Seminar Room 70A)

Abstract: The unit circle viewed as a Riemannian manifold has diameter (not 2 but rather) π, illustrating the difference between intrinsic and ambient distance. Gromov proceeded to erase the difference by pointing out that when a Riemannian manifold is embedded in L∞, the intrinsic and the ambient distances coincide in a way that is as counterintuitive as it is fruitful. Witness the results of his 1983 Filling paper.

2015
Dec
02

11:00am to 12:45pm

Ross building, Hebrew University (Seminar Room 70A)

Abstract: The classical theorem of Van Kampen and Flores states that the k-dimensional skeleton of (2k+2)-dimensional simplex cannot be embedded into R2k.
We present a version of this theorem for chain maps and as an application we prove a qualitative topological Helly-type theorem.
If we define the Helly number of a finite family of sets to be one if all sets in the family have a point in common and as the largest size of inclusion-minimal subfamily with empty intersection otherwise, the theorem can be stated as follows:

2016
Apr
06

11:00am to 12:45pm

Levi building, Hebrew University ( Room 06)

**Note the special location**
Abstract:

2016
Mar
23

11:00am to 12:45pm

Ross building, Hebrew University (Seminar Room 70A)

Abstract:
In this pair of talks I will discuss how to obtain fixed-point expressions
for open Gromov-Witten invariants. The talks will be self-contained,
and the second talk will only require a small part of the first talk,
which we will review.
The Atiyah-Bott localization formula has become a valuable tool for
computation of symplectic invariants given in terms of integrals on
the moduli spaces of closed stable maps. In contrast, the moduli spaces
of open stable maps have boundary which must be taken into account
in order to apply fixed-point localization. Homological perturbation

2016
Jan
20

11:00am to 12:45pm

Ross building, Hebrew University (Seminar Room 70A)

Abstract: One of the first applications of model categories was Quillen homology. Building on the notion of Beck modules, one defines the cotangent complex of an associative or commutative (dg)-algebras as the derived functor of its abelianization. The latter is a module over the original algebra, and its homology groups are called the (Andre'-)Quillen homology. The caveat of this approach is that the cotangent complex is not defined as a functor on the category of all algebras.

2015
Nov
11

11:00am to 12:45pm

Ross building, Hebrew University (Seminar Room 70A)

Abstract: An elastic energy functional of a Riemannian manifold is a function that measures the distance of an embedding u:→ℝd from being isometric. In many applications, the manifold in consideration is actually a limit of other manifolds, that is, is a limit of n in some sense. Assuming that we have an elastic energy functional for each n, can we obtain an energy functional of which is a limit of the functionals of n?

2016
Mar
09

11:00am to 12:45pm

Ross building, Hebrew University (Seminar Room 70A)

Abstract: The contact mapping class group of a contact manifold V is the set of contact isotopy classes of its contactomorphisms. When V is the 2n-dimensional (n at least 2) Am Milnor fiber times the circle, with a natural contact structure, we show that the full braid group Bm+1 on m+1strands embeds into the contact mapping class group of V. We deduce that when n=2, the subgroup Pm+1 of pure braids is mapped to the part of the contact mapping class group consisting of smoothly trivial classes. This solves the contact isotopy problem for V.

2015
Dec
16

11:00am to 2:30pm

Ross building, Hebrew University (Seminar Room 70A)

Abstract: For a toric Fano manifold $X$ denote by $Crit(X) \subset (\mathbb{C}^{\ast})^n$ the solution scheme of the Landau-Ginzburg system of equations of $X$. Examples of toric Fano manifolds with $rk(Pic(X)) \leq 3$ which admit full strongly exceptional collections of line bundles were recently found by various authors. For these examples we construct a map $E : Crit(X) \rightarrow Pic(X)$ whose image $\mathcal{E}=\left \{ E(z) \vert z \in Crit(X) \right \}$ is a full strongly exceptional collection satisfying the M-aligned property.

2016
Jun
15

11:00am to 12:45pm

Ross building, Hebrew University (Seminar Room 70A)

Abstract: In the paper "Formal noncommutative symplectic geometry'', Maxim Kontsevich introduced three versions of cochain complexes GCCom, GCLie and GCAs "assembled from'' graphs with some additional structures. The graph complex GCCom (resp. GCLie, GCAs) is related to the operad Com (resp. Lie, As) governing commutative (resp. Lie, associative) algebras. Although the graphs complexes GCCom, GCLie and GCAs (and their generalizations) are easy to define, it is hard to get very much information about their cohomology spaces.

2016
Mar
02

11:00am to 12:45pm

Ross building, Hebrew University (Seminar Room 70A)

Abstract: I will review a beautiful construction of an infinite collection of monotone Lagrangian tori in the projective plane (and other del Pezzo surfaces) due to Renato Vianna. These tori are obtained from a single one by a procedure called mutation, and I will talk about the wall-crossing formula which relates this geometric procedure to algebraic mutation known from cluster algebra. A proof of the wall-crossing formula is work in progress.