Bourbaki goes to Luxembourg (garden)

On march 15th, 2009, I gave the Bourbaki lecture on “the differentiable sphere theorem”. As a protest against the government policy, the beginning of the lecture has been given on the bandstand of Jardin du Luxembourg. After ten minutes we had to leave when the senate police arrived. We then finished the lecture in  the regular room at Institut Henri Poincaré. A video is posted on You Tube.

Collapsing irreducible 3-manifolds with nontrivial fundamental group

This is a joint work with Laurent Bessières, Michel Boileau, Sylvain Maillot and Joan Porti. Let M be a closed, orientable, irreducible, non-simply connected 3-manifold.We prove that if M admits a sequence of Riemannian metrics which volume-collapses and whose sectional curvature is locally controlled, then M is a graph manifold. This is the last step in Perelman’s proof of Thurston’s Geometrisation Conjecture.

The reference is:

L. Bessières, G. Besson, M. Boileau, S. Maillot and J. Porti Collapsing irreducible 3-manifolds with nontrivial fundamental group Invent math (2010) 179: 435–460.