English

The behavior of differential, quadratic and bilinear forms under purely inseparable field extensions

Commutative Algebra 2016-10-19 v5

Abstract

Let FF be a field of characteristic pp and let E/FE/F be a purely inseparable field extension. We study the group Hpn+1(F)H_p^{n+1}(F) of classes of differential forms under the restriction map Hpn+1(F)Hpn+1(E)H_p^{n+1}(F)\to H_p^{n+1}(E) and give a system of generators of the kernel Hpn+1(E/F)H_p^{n+1}(E/F). In the case p=2p=2, we use this to determine the kernel Wq(E/F)W_q(E/F) of the restriction map Wq(F)Wq(E)W_q(F) \to W_q(E) between the group of nonsingular quadratic forms over FF and over EE. We also deduce the corresponding result for the bilinear Witt kernel W(E/F)W(E'/F) of the restriction map W(F)W(E)W(F) \to W(E'), where E/FE'/F denotes a modular purely inseparable field extension.

Keywords

Cite

@article{arxiv.1512.02079,
  title  = {The behavior of differential, quadratic and bilinear forms under purely inseparable field extensions},
  author = {Marco Sobiech},
  journal= {arXiv preprint arXiv:1512.02079},
  year   = {2016}
}