Speaker: Pierre-Louis Blayac
Date: February 12, 2026
Affiliation: Universtiy of Strasbourg, France

Abstract: An open convex subset of the real projective space is called divisible if it is preserved and acted on cocompactly by some discrete group of projective transformations. The study of Divisible Convex Sets was initiated by Benzécri in the 60s, and since then the story of this seemingly narrow field of research has seen a lot of progress and several surprising turns of events, revealing links with many kinds of mathematics: dynamical systems, geometric group theory, Coxeter groups, moduli spaces, geometrisation of $3$-manifolds. We will review this story, with a focus on one particularly delicate aspect: the construction of examples. In particular, we will explain the construction of non-strictly convex non-symmetric divisible convex sets in any dimension.