2019 Mar 26

Dynamics Seminar: Nattalie Tamam "Diagonalizable groups with non-obvious divergent trajectories"

12:00pm to 1:00pm


Manchester faculty club
Singular vectors are the ones for which Dirichlet’s theorem can be infinitely improved. For example, any rational vector is singular. The sequence of approximations for any rational vector q is 'obvious'; the tail of this sequence contains only q. In dimension one, the rational numbers are the only singulars. However, in higher dimensions there are additional singular vectors. By Dani's correspondence, the singular vectors are related to divergent trajectories in Homogeneous dynamical systems. A corresponding 'obvious' divergent trajectories can also be defined.
2019 Mar 25

NT & AG Lunch: Ehud DeShalit "An overview of class field theory, II"

1:00pm to 2:00pm


Faculty lounge, Math building
Class field theory classifies abelian extensions of local and global fields in terms of groups constructed from the base. We shall survey the main results of class field theory for number fields and function fields alike. The goal of these introductory lectures is to prepare the ground for the study of explicit class field theory in the function field case, via Drinfeld modules. I will talk for the first 2 or 3 times.
2019 Mar 26

T&G: Vivek Shende (Berkeley), Quantum topology from symplectic geometry

1:00pm to 2:30pm


Room 110, Manchester Building, Jerusalem, Israel
The discovery of the Jones polynomial in the early 80's was the beginning of ``quantum topology'': the introduction of various invariants which, in one sense or another, arise from quantum mechanics and quantum field theory. There are many mathematical constructions of these invariants, but they all share the defect of being first defined in terms of a knot diagram, and only subsequently shown by calculation to be independent of the presentation. As a consequence, the geometric meaning has been somewhat opaque.