Finite group torsors for the qfh topology, by J.F. Jardine
Suppose that S is a Noetherian scheme and that G is a group scheme
which is finite and etale over S. This note shows that G-torsors for
the qfh topology coincide up to isomorphism with torsors induced up
from the etale topology over such schemes S, in the sense that the
obvious comparison function between isomorphism classes of torsors is
a bijection. This is the non-abelian analogue of a comparison theorem
of Voevodsky which identifies etale and qfh cohomology for coefficient
sheaves represented by finite etale abelian group schemes. The method
of proof is to show that the qfh stack completion of the group scheme
G induces a local weak equivalence of classifying simplicial sheaves
for the etale topology.
J.F. Jardine <jardine@uwo.ca>