2017 Nov 28

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

12:00pm to 1:30pm


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.
2015 Dec 07

Number theory: Jean-Baptiste Teyssier (HUJI) "Kedlaya-Mochizuki theorem and applications"

4:00pm to 5:15pm


Ross Building, room 70A
Let X be a complex manifold and let M be a meromorphic connection on X with
poles along a normal crossing divisor D. Levelt-Turrittin theorem asserts that the pull-back of M to the formal neighbourhood of a codimension 1 point in D decom poses (after ramification) into elementary factors easy to work with.
This decomposition may not hold at some other points of D. When it does, we say
that M has good formal decomposition along D. A conjecture of Sabbah, recently
proved by Kedlaya and Mochizuki independently, asserts roughly the
2015 Nov 09

Number theory: Ishai Dan-Cohen (Essen), "Towards Chabauty-Kim loci for the polylogarithmic quotient over an arbitrary number field"

4:00pm to 5:45pm


Ross Building, room 70, Jerusalem, Israel
Title: Towards Chabauty-Kim loci for the polylogarithmic quotient over an arbitrary number field
Abstract: Let K be a number field and let S be an open
subscheme of Spec O_K.
Minhyong Kim has developed a method for
bounding the set of S-valued points on a
hyperbolic curve X over S; his method opens
a new avenue in the quest for an "effective
Mordell conjecture".
But although Kim's approach has lead to the
construction of explicit bounds in special
cases, the problem of realizing the potential
2017 Dec 19

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

1:00pm to 2:30pm


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.
2015 Dec 17

Groups & dynamics: Rene Rühr, Distribution of Shapes of Orthogonal Lattices

10:00am to 11:30am


Ross building, Hebrew University of Jerusalem, (Room 70)
To every topological group, one can associate a unique universal
minimal flow (UMF): a flow that maps onto every minimal flow of the
group. For some groups (for example, the locally compact ones), this
flow is not metrizable and does not admit a concrete description.
However, for many "large" Polish groups, the UMF is metrizable, can be
computed, and carries interesting combinatorial information. The talk
will concentrate on some new results that give a characterization of
metrizable UMFs of Polish groups. It is based on two papers, one joint
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


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.
2015 Nov 19

Groups & dynamics: Lei Yang (HUJI) "Equidistribution of expanding translates of curves in homogeneous spaces and Diophantine approximation"

10:00am to 11:00am


Ross 70
Title: Equidistribution of expanding translates of curves in homogeneous spaces and Diophantine approximation.
We consider an analytic curve $\varphi: I \rightarrow \mathbb{M}(n\times m, \mathbb{R}) \hookrightarrow \mathrm{SL}(n+m, \mathbb{R})$ and embed it into some homogeneous space $G/\Gamma$, and translate it via some diagonal flow
2016 Nov 03

Groups and dynamics - Misha Belolipetsky

10:30am to 11:30am


Ross 70
Speaker: Misha Belolipetsky
Title: Arithmetic Kleinian groups generated by elements of finite order
We show that up to commensurability there are only finitely many
cocompact arithmetic Kleinian groups generated by rotations. The proof
is based on a generalised Gromov-Guth inequality and bounds for the
hyperbolic and tube volumes of the quotient orbifolds. To estimate the
hyperbolic volume we take advantage of known results towards Lehmer's
problem. The tube volume estimate requires study of triangulations of