DMS Algebra Seminar

Speaker: Wanlin Li (Washington University in St. Louis)

Title: Algebraic and arithmetic properties of curves via Galois cohomology

Abstract: A lot of the algebraic and arithmetic information of a curve is contained in its interaction with the Galois group. This draws inspiration from topology, where given a family of curves over a base B, the fundamental group of B acts on the cohomology of the fiber. As an arithmetic analogue, given an algebraic curve C defined over a non-algebraically closed field K, the absolute Galois group of K acts on the etale cohomology of the geometric fiber and this action gives rise to various Galois cohomology classes. In this talk, we discuss how to use these classes to detect algebraic and arithmetic properties of the curve, such as the rational points (following Grothendieck's section conjecture) and whether the curve is hyperelliptic.