

Strongly ergodic equivalence relations and full factors
By Amine Marrakchi


A split version of the mixing conjecture and applications
By Philippe Michel


Conformal measures and currents in holomorphic dynamics
By Mikhail Lyubich
Appears in collection : Differential Geometry, Billiards, and Geometric Optics / Géométrie différentielle, billards et optique géométrique
In an ordinary billiard trajectories of a Hamiltonian system are reflected after a collision with a hypersurface (scatterer). If the scatterer has codimension more than one, we say that the billiard is degenerate. Degenerate billiards appear e.g. as limits of systems with singularities in celestial mechanics. We discuss the existence of trajectories of such systems shadowing trajectories of a degenerate billiard.