English

Forms over fields and Witt's lemma

K-Theory and Homology 2020-09-09 v3 Algebraic Topology

Abstract

We give an overview of the general framework of forms of Bak, Tits and Wall, when restricting to vector spaces over fields, and describe its relationship to the classical notions of Hermitian, alternating and quadratic forms. We then prove a version of Witt's lemma in this context, showing in particular that the action of the group of isometries of a space equipped with a form is transitive on isometric subspaces.

Cite

@article{arxiv.1811.12219,
  title  = {Forms over fields and Witt's lemma},
  author = {David Sprehn and Nathalie Wahl},
  journal= {arXiv preprint arXiv:1811.12219},
  year   = {2020}
}

Comments

Final version, to appear in Math. Scand

R2 v1 2026-06-23T06:25:20.218Z