SMS scnews item created by Anthony Henderson at Mon 17 Sep 2007 1203
Type: Seminar
Distribution: World
Expiry: 21 Sep 2007
Calendar1: 21 Sep 2007 1205-1255
CalLoc1: Carslaw 373
CalTitle1: Algebra Seminar: O’Sullivan -- The generalised Jacobson-Morosov theorem

Algebra Seminar

The generalised Jacobson-Morosov theorem

Peter O’Sullivan

21st September, 12:05-12:55pm, Carslaw 373


The classical Jacobson-Morosov theorem states that over a field k of characteristic zero, the embedding of the additive group Ga into SL2 is universal among homomorphisms from Ga to a reductive group, in the sense that any such homomorphism factors through the embedding, and any two factorisations are conjugate.

Based on a categorical splitting theorem, Andre and Kahn proved that a similar universal property holds with Ga replaced by an arbitrary algebraic group over k and SL2 by an appropriate limit of reductive groups. In this talk a more geometric approach to this result will be given, using actions of reductive groups on affine schemes.

After the seminar we will take the speaker to lunch.

See the Algebra Seminar web page for information about other seminars in the series.

Anthony Henderson