Cohomological invariants in positive characteristic
Algebraic Geometry
2020-03-20 v1 Group Theory
K-Theory and Homology
Abstract
We determine the mod p cohomological invariants for several affine group schemes G in chararacteristic p. These are invariants of G-torsors with values in etale motivic cohomology, or equivalently in Kato's version of Galois cohomology based on differential forms. In particular, we find the mod 2 cohomological invariants for the symmetric groups and the orthogonal groups in characteristic 2, which Serre computed in characteristic not 2. We also determine all operations on the mod p etale motivic cohomology of fields, extending Vial's computations of the operations on the mod p Milnor K-theory of fields.
Keywords
Cite
@article{arxiv.2003.08568,
title = {Cohomological invariants in positive characteristic},
author = {Burt Totaro},
journal= {arXiv preprint arXiv:2003.08568},
year = {2020}
}
Comments
37 pages