Series: Mathematics Colloquium

Date: Thursday, October 3, 2002

Time: 4:30 - 5:30 PM

Place: 102 McAllister Building

Host: Sergei Tabachnikov

Refreshments: 4:00 - 4:30 PM, in 212 McAllister

Speaker: Joseph Landsberg, Georgia Tech

Title: Series of Lie groups, after Freudenthal, Deligne and Vogel

Abstract: 

I will discuss various ways Lie groups have been organized into
``series'', with emphasis on the geometric models of Freudenthal and
the categorical models of Deligne and Vogel.  In recent work with
L. Manivel these perspectives provided the inspiration to obtain new
geometric insight into the structure of nilpotent orbits and to prove
striking formulas, including vast generalizations of the Deligne
dimension formulas for the exceptional groups. (Deligne obtained the
formulas via computer experiments.)