17:00 -- 18:30 Θw€Θ(εwξκLpX)
Tea: 16:30 -- 17:00 R[
Last updated September 21, 2018
102ϊ -- 056Ί, 17:00 -- 18:30
An Alexander polynomial for MOY graphs
Abstract: An MOY graph is a trivalent graph equipped with a balanced coloring.
In this talk, we define a version of Alexander polynomial for an MOY graph.
This polynomial is the Euler characteristic of the Heegaard Floer homology of an MOY graph.
We give a characterization of the polynomial, which we call MOY-type relations,
and show that it is equivalent to Virofs gl(1 | 1)-Alexander polynomial of a graph.
(A part of the talk is a joint work of Zhongtao Wu)
109ϊ -- 056Ί, 17:00 -- 18:30
Boris Hasselblatt (Tufts University)
Foulon surgery, new contact flows, and dynamical complexity
Abstract: A refinement of Dehn surgery produces new contact flows that are unusual and interesting in several ways.
The geodesic flow of a hyperbolic surface becomes a nonalgebraic contact Anosov flow with larger orbit growth,
and the purely periodic fiber flow becomes parabolic or hyperbolic.
Moreover, Reeb flows for other contact forms for the same contact structure have the same complexity.
Finally, an idea by Vinhage promises a quantification of the complexity increase.
1023ϊ -- 056Ί, 17:00 -- 18:30
François Fillastre (Université de Cergy-Pontoise)
Co-Minkowski space and hyperbolic surfaces
Abstract: There are many ways to parametrize two copies of Teichmueller space by constant curvature -1 Riemannian or Lorentzian 3d manifolds
(for example the Bers double uniformization theorem). We present the co-Minkowski space (or half-pipe space),
which is a constant curvature -1 degenerated 3d space, and which is related to the tangent space of Teichmueller space.
As an illustration, we give a new proof of a theorem of Thurston saying that,
once the space of measured geodesic laminations on a compact hyperbolic surface is identified with the tangent space of Teichmueller space via infinitesimal earthquake,
then the length of laminations is an asymmetric norm. Joint work with Thierry Barbot (Avignon).