"On the structure of torsors under affine group schemes over an 
algebraically closed field"

Abstract: It is well known that all torsors under an affine algebraic 
group over an algebraically closed field are trivial.
We show that under suitable conditions this also holds if the the group 
is not necessarily of finite type. This has an application to 
isomorphisms of fibre functors on neutral Tannakian categories.