Topology & Geometry

The Topology & Geometry seminar meets on Tuesdays at 13:00 at room 70 in the Ross Building.
2018 Apr 10

T&G: Jesse Kasse (University of South Carolina), How to count lines on a cubic surface arithmetically

1:00pm to 2:30pm

Location:

Room 110, Manchester Building, Jerusalem, Israel
2018 Apr 24

T&G: Anton Khoroshkin (HSE), Compactified moduli spaces of rational curves with marked points as homotopy quotients of operads

1:00pm to 2:30pm

Location:

Room 110, Manchester Building, Jerusalem, Israel
2018 Mar 27

T&G: Lev Buhovski (Tel Aviv), Bounding the Poisson bracket invariant on surfaces

1:00pm to 2:30pm

Location:

Room 110, Manchester Building, Jerusalem, Israel
2016 Jan 20

Topology & geometry, Matan Prasma (Radboud University), "Model-categorical cotangent complex formalism"

11:00am to 12:45pm

Location:

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.
2017 May 09

Topology & Geometry Seminar: Serap Gurer (Galatasaray University), "(Co)homology theories on diffeological spaces".

11:00am to 12:00pm

Location:

Ross A70.
Abstract: In this talk, I will introduce diffeological spaces and some (co)homology theories on these spaces. I will also talk on Thom-Mather spaces and their (co)homology in the diffeological context.
2017 Jun 13

Topology and Geometry Seminar: Alexander Caviedes Castro (Tel-Aviv University), "Symplectic capacities and Cayley graphs"

1:00pm to 1:50pm

Location:

Ross 70A
Abstract: The Gromov non-squeezing theorem in symplectic geometry states that is not possible to embed symplectically a ball into a cylinder of smaller radius, although this can be done with a volume preserving embedding. Hence, the biggest radius of a ball that can be symplectically embedded into a symplectic manifold can be used as a way to measure the "symplectic size'' of the manifold. We call the square of this radius times the number \pi the Gromov width of the symplectic manifold. The Gromov width as a symplectic invariant is extended through the notion of "Symplectic Capacity".
2018 Apr 30

Zabrodsky Lecture: Camillo De Lellis (Universitat Zurich), Regularity of area minimizing currents in codimension higher than 1: interior

2:00pm to 3:00pm

Location:

Room 70A, Ross Building, Jerusalem, Israel
2018 May 01

Zabrodsky Lecture: Camillo De Lellis (Universitat Zurich), Regularity of area minimizing currents in codimension higher than 1: boundary

2:00pm to 3:00pm

Location:

Room 70A, Ross Building, Jerusalem, Israel
2017 Nov 28

T&G: Benjamin Ackermann (Hebrew University), Kodaira's embedding theorem

12:00pm to 1:30pm

Location:

Room 70A, Ross Building, Jerusalem, Israel
In this talk we present a proof of the Kodaira's theorem that gives a sufficient condition on the existence of an embedding of a Kahler manifold into CPn. This proof is based on the Kodaira Vanishing theorem, using a sheaf-cohomological translation of the embedding conditions. לאירוע הזה יש שיחת וידאו. הצטרף: https://meet.google.com/mcs-bwxr-iza
2017 Dec 19

T&G: Yakov Eliashberg (Stanford), Simplifying singularities of Lagrangian skeleta

1:00pm to 2:30pm

Location:

Room 63, Ross Building, Jerusalem, Israel
I will discuss in the talk David Nadler’s “arborealizaton conjecture” and will sketch its proof. The conjecture states that singularities of a Lagrangian skeleton of a symplectic Weinstein manifold could be always simplified to a finite list of singularities, called arboreal”. This is a joint work with Daniel Albarez-Gavela, David Nadler and Laura Starkston.
2017 Dec 12

T&G: Yoel Groman (Columbia), Generation of the Fukaya category of a Lagrangian torus fibration by a section

1:00pm to 2:30pm

Location:

Room 70A, Ross Building, Jerusalem, Israel
The (wrapped) Fukaya category of a symplectic manifold is a category whose objects are Lagrangian submanifolds and which contains a wealth of information about the symplectic topology. I will discuss the construction of the wrapped Fukaya category for certain completely integrable Hamiltonian systems. These are 2n-dimensional symplectic manifolds carrying a system of n commuting Hamiltonians surjecting onto Euclidean space. This gives rise to a Lagrangian torus fibration with singularities.
2017 Nov 21

T&G: Semyon Alesker (Tel Aviv University), Calabi type problem for Monge-Ampere equations on HKT manifolds

12:00pm to 1:30pm

Location:

Room 70A, Ross Building, Jerusalem, Israel
Real and complex Monge-Ampere equations play a central role in several branches of geometry and analysis. We introduce a quaternionic version of a Monge-Ampere equation which is an analogue of the famous Calabi problem in the complex case. It is a non-linear elliptic equation of second order on so called HyperKahler with Torsion (HKT) manifolds (the latter manifolds were introduced by physicists in 1990's). While in full generality it is still unsolved, we will describe its solution in a special case and some
2017 Dec 05

T&G: Michael Farber (IIAS), Robot motion planning and Bredon equivariant cohomology

12:00pm to 1:30pm

Location:

Room 70A, Ross Building, Jerusalem, Israel
I will describe a topological approach to the robot motion planning problem focusing mainly on the case of aspherical configuration spaces.
2015 Nov 25

Topology & geometry: Lara Simone Suárez (HUJI), "Exact Lagrangian cobordism and pseudo-isotopy"

11:00am to 12:45pm

Location:

Ross building, Hebrew University (Seminar Room 70A)
Abstract: Consider two Lagrangian submanifolds L, L′ in a symplectic manifold (M,ω). A Lagrangian cobordism (W;L,L′) is a smooth cobordism between L and L′ admitting a Lagrangian embedding in (([0,1]×R)×M,(dx∧dy)⊕ω) that looks like [0,ϵ)×{1}×L and (1−ϵ,1]×{1}×L′ near the boundary. In this talk we will show that under some topological constrains, an exact Lagrangian cobordism (W;L,L′) with dim(W)>5 is diffeomorphic to [0,1]×L.
2016 Jan 20

Topology & geometry, Matan Prasma (Radboud University), "Model-categorical cotangent complex formalism"

11:00am to 12:45pm

Location:

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.