English

Types of Linkage of Quadratic Pfister Forms

Commutative Algebra 2018-11-13 v3 Algebraic Geometry

Abstract

Given a field FF of positive characteristic pp, θHpn1(F)\theta \in H_p^{n-1}(F) and β,γF×\beta,\gamma \in F^\times, we prove that if the symbols θdββ\theta \wedge \frac{d \beta}{\beta} and θdγγ\theta \wedge \frac{d \gamma}{\gamma} in Hpn(F)H_p^n(F) share the same factors in Hp1(F)H_p^1(F) then the symbol θdββdγγ\theta \wedge \frac{d \beta}{\beta} \wedge \frac{d \gamma}{\gamma} in Hpn+1(F)H_p^{n+1}(F) is trivial. We conclude that when p=2p=2, every two totally separably (n1)(n-1)-linked nn-fold quadratic Pfister forms are inseparably (n1)(n-1)-linked. We also describe how to construct non-isomorphic nn-fold Pfister forms which are totally separably (or inseparably) (n1)(n-1)-linked, i.e. share all common (n1)(n-1)-fold quadratic (or bilinear) Pfister factors.

Keywords

Cite

@article{arxiv.1806.03603,
  title  = {Types of Linkage of Quadratic Pfister Forms},
  author = {Adam Chapman and Andrew Dolphin},
  journal= {arXiv preprint arXiv:1806.03603},
  year   = {2018}
}