English

On a generalized Brauer group in mixed characteristic cases

Number Theory 2020-11-18 v3 Algebraic Geometry

Abstract

We define a generalization of the Brauer group HBn(X)\operatorname{H}_\mathrm{B}^{n}(X) for an equi-dimensional scheme XX and n>0n>0. In the case where XX is the spectrum of a local ring of a smooth algebra over a discrete valuation ring, HBn(X)\operatorname{H}_\mathrm{B}^{n}(X) agrees with the \'{e}tale motivic cohomology Heˊtn+1(X,Z(n1))\operatorname{H}^{n+1}_{\mathrm{\acute{e}t}}\left(X, \mathbb{Z}(n-1)\right). We prove (a part of) the Gersten-type conjecture for the generalized Brauer group for a local ring of a smooth algebra over a mixed characteristic discrete valuation ring and an isomorphism HBn(R)HBn(k) \operatorname{H}_\mathrm{B}^{n}\left( R \right) \simeq \operatorname{H}_\mathrm{B}^{n}\left( k \right) for a henselian local ring RR of a smooth algebra over a mixed characteristic discrete valuation ring and the residue field kk. As an application, we show local-global principles for Galois cohomology groups over function fields of smooth curves over a mixed characteristic excellent henselian discrete valuation ring.

Keywords

Cite

@article{arxiv.1710.11449,
  title  = {On a generalized Brauer group in mixed characteristic cases},
  author = {Makoto Sakagaito},
  journal= {arXiv preprint arXiv:1710.11449},
  year   = {2020}
}

Comments

29 pages, Final version, Revised after the referee report

R2 v1 2026-06-22T22:31:12.748Z