English

On the residue fields of Henselian valued stable fields

Rings and Algebras 2011-11-10 v4 Commutative Algebra

Abstract

Let (K,v)(K, v) be a Henselian valued field satisfying the following conditions, for a given prime number pp: (i) central division KK-algebras of (finite) pp-primary dimensions have Schur indices equal to their exponents; (ii) the value group v(K)v(K) properly includes its subgroup pv(K)pv(K). The paper shows that if K^\hat K is the residue field of (K,v)(K, v) and R^\hat R is an intermediate field of the maximal pp-extension K^(p)/K^\hat K (p)/\hat K, then the natural homomorphism Br(K^)(\hat K) \to Br(R^)(\hat R) of Brauer groups maps surjectively the pp-component Br(K^)p(\hat K)_{p} on Br(R^)p(\hat R)_{p}. It proves that Br(K^)p(\hat K)_{p} is divisible, if p>2p > 2 or K^\hat K is a nonreal field, and that Br(K^)2(\hat K)_{2} is of order 2 when K^\hat K is formally real. We also obtain that R^\hat R embeds as a K^\hat K-subalgebra in a central division K^\hat K-algebra Δ^\hat \Delta if and only if the degree [R^ ⁣:K^][\hat R\colon \hat K] divides the index of Δ^\hat \Delta .

Keywords

Cite

@article{arxiv.math/0412544,
  title  = {On the residue fields of Henselian valued stable fields},
  author = {I. D. Chipchakov},
  journal= {arXiv preprint arXiv:math/0412544},
  year   = {2011}
}

Comments

Final form, to appear in J. Algebra 319 (2008), No 1, 16-49