Local Global Principles for Galois Cohomology

Local Global Principles for Galois Cohomology - Julia Hartmann

Julia Hartmann
RWTH Aachen University; Member, School of Mathematics, IAS
December 13, 2012

We consider Galois cohomology groups over function fields F of curves that are defined over a complete discretely valued field.
Motivated by work of Kato and others for n=3, we show that local-global principles hold for
$H^n(F, Z/mZ(n-1))$ for all n>1.
In the case n=1, a local-global principle need not hold. Instead, we will see that the obstruction to a local-global principle for $H^1(F,G)$, a Tate-Shafarevich set, can be described explicitly for many (not necessarily abelian) linear algebraic groups G.
Concrete applications of the results include central simple algebras and Albert algebras.