The finiteness of the Tate–Shafarevich group over function fields for algebraic tori defined over the base field

Rapinchuk AS, Rapinchuk IA. The finiteness of the Tate–Shafarevich group over function fields for algebraic tori defined over the base field. Comptes Rendus Mathematique . 2024;362:739–749.

Abstract

Let K be a field and V be a set of rank one valuations of K. The corresponding Tate–Shafarevich group of a K-torus T is Ш(T,V)=ker(H1(K,T)→∏v∈VH1(Kv,T)). We prove that if K=k(X) is the function field of a smooth geometrically integral quasi-projective variety over a field k of characteristic 0 and V is the set of discrete valuations of K associated with prime divisors on X, then for any torus T defined over the base field k, the group Ш(T,V) is finite in the following situations: (1) k is finitely generated and X(k)≠∅; (2) k is a number field.

Last updated on 09/19/2024