Ronan Terpereau (Bourgogne) 17 September 2020 "Actions of connected algebraic groups on rational 3-dimensional Mori fibrations" In this talk we will study the connected algebraic groups acting on Mori fibrations X -> Y with X a rational threefold and Y a curve or a surface. We will see how these groups can be classified, using the minimal model program (MMP) and the Sarkisov program, and how our results make possible to recover most of the classification of the connected algebraic subgroups of the Cremona group Bir(P^3) obtained by Hiroshi Umemura in the 1980's when the base field is the field of complex numbers.
