10h-11h : Dan Corey (Université de Las Vegas)

Titre : Singular matroid realization spaces

Résumé : By Mnëv's universality theorem, every singularity type appears in the realization spaces of a rank 3 matroid. While the proofs of this theorem are constructive, the resulting matroids have large ground sets even for the simplest singularities. I will present recent joint work with Dante Luber (TU Berlin) where we show that, over the complex numbers, the realization spaces of rank 3 matroids on ≤ 11 elements are all smooth, but there are singular realization spaces for matroids on ≥ 12 elements. We use this result to show that the open Grassmannian is not schön in the sense of Tevelev. 

11h15-12h15 : Leonid Monin (EPFL, Lausanne)

Titre : TBA