Claire Voisin : Decomposition of the diagonal and stable birational invariants

Posted by Izzet Coskun , part of the Algebraic Geometry Seminar.

At

April 1, 2015, 4 p.m.

In

SEO 427

Abstract

The Lüroth problem asks whether a unirational variety is rational. It has a negative answer starting from dimension 3 and can be attacked by various geometric approaches. For the stable Lüroth problem, where "rational" is replaced by "stably rational" , only the Artin-Mumford approach had been used up to now to solve the problem in dimension 3. Using the notion of decomposition of the diagonal, we exhibit many unirational threefolds which are not stably rational while their Artin-Mumford invariant is trivial.