Variétés rationnelles

In 1981, Sansuc obtained a formula for Tamagawa numbers of reductive groups over number fields, modulo some then unknown results on the arithmetic of simply connected groups which have since been proven, particularly Weil's conjecture on Tamagawa numbers over number fields. One easily deduces that this same formula holds for all linear algebraic groups over number fields. Sansuc's method still works to treat reductive groups in the function field setting, thanks to the recent resolution of Weil's conjecture in the function field setting by Lurie and Gaitsgory. However, due to […]

In this talk, I will discuss the so-called generic cohomology of a function field, which can be constructed using any suitable cohomology theory. While this object resembles Galois cohomology in many ways, there are subtle but important differences that give this object a more refined structure. I will focus primary on a new birational anabelian result which uses the Hodge-theoretic avatar of generic cohomology.