Séminaires : Séminaire d'Algèbre

Equipe(s) : gr,
Responsables :J. Alev, D. Hernandez, B. Keller, Th. Levasseur, et S. Morier-Genoud.
Email des responsables : Jacques Alev <jacques.alev@univ-reims.fr>, David Hernandez <david.hernandez@imj-prg.fr>, Bernhard Keller <bernhard.keller@imj-prg.fr>, Thierry Levasseur <Thierry.Levasseur@univ-brest.fr>, Sophie Morier-Genoud <sophie.morier-genoud@imj-prg.fr>
Salle : 001
Adresse :IHP


Orateur(s) Susan SIERRA - Edimbourg,
Titre Dynamics of automorphisms, noetherian rings, and the Virasoro algebra
Horaire14:00 à 15:00
RésumeThis talk links algebraic geometry, noncommutative ring theory, and the Virasoro Lie algebra, known for its importance in conformal field theory. We begin with a question in ring theory. Let X be a projective surface with an automorphism a, and consider the skew polynomial extension k(X)[t; a]. Which finitely generated graded subalgebras are noetherian? It turns out that, morally, if a has dense orbits on X there are many noetherian subalgebras, and if not there are few. In the first part of the talk we explain this. In the second, we show how this leads to a proof that the enveloping algebra of the Virasoro algebra is not noetherian.