University of Georgia
Department of Mathematics

Seminar Schedule
August 15-19, 2005
All Seminars are held in Boyd Graduate Studies Bldg. unless otherwise noted.

TUESDAY, August 16, 2005

VIGRE Grad Student Seminar
2:00pm-3:00pm. Room 304
Speaker: Dan Nakano, University of Georgia
Title: VIGRE group introduction: Lie algebra cohomology and its applications (algebra)

THURSDAY, August 18, 2005

VIGRE Grad Student Seminar
2:00-3:00pm Room 303
Speaker: Jason Cantarella, University of Georgia
Title: VIGRE group introduction (differential geometry)

FRIDAY, August 19, 2005

Topology/Geometry Seminar
2:30-3:30pm, Room 326
Speaker: Frederic Paulin, ENS-Paris
Title of talk: The ubiquity of Hall rays
Abstract: The set, called the Lagrange spectrum, of the approximation constants of irrational real number by rational ones starts with a maximal initial segment of the form $[0,\mu]$, called the Hall ray. The existence of the Hall ray can be translated in terms of the behaviour of the geodesic flow on the modular once punctured hyperbolic torus. We prove that this phenomenon has nothing to do with arithmetic nor constant curvature, nor dimension 2, but holds true say for any finite volume cusped negatively curved Riemannian manifold of dimension at least 3. This is a joint work with Jouni Parkkonen.