The Algebra Seminar on Friday 25 March will be given by Gus Lehrer. --------------------------------------------------------------------- Speaker: Gus Lehrer (University of Sydney) Date: Friday 25 March Time: 12.05-12.55pm Venue: Carslaw 175 Title: The second fundamental theorem of invariant theory for the orthogonal group Abstract: I shall explain how the commutant of the classical orthogonal group action on tensor space has a presentation which is obtained from the Brauer algebra by adding one single idempotent relation, which will be explicitly described. This solves a 74 year old mystery. Applications will be given via cellular theory to multiplicity theory in characacteristics other than zero, and to the quantum case at roots of unity. This is joint work with Ruibin Zhang. ---------------------------------------------------------------------