Generic Splitting Fields of Central Simple Algebras: Galois Cohomology and Nonexcellence
Authors: Izhboldin O.T.1; Karpenko N.A.2
Source: Algebras and Representation Theory, Volume 2, Number 1, March 1999 , pp. 19-59(41)
Publisher: Springer
Abstract:
A field extension L / F is called excellent if, for any quadratic form
over F, the anisotropic part (
L)an of
over L is defined over F; L / F is called universally excellent if L
E / E is excellent for any field extension E / F. We study the excellence property for a generic splitting field of a central simple F-algebra. In particular, we show that it is universally excellent if and only if the Schur index of the algebra is not divisible by 4. We begin by studying the torsion in the second Chow group of products of SeveriBrauer varieties and its relationship with the relative Galois cohomology group H3(L / F) for a generic (common) splitting field L of the corresponding central simple F-algebras.
Keywords: quadratic form over a field; excellent field extension; central simple algebra; SeveriBrauer variety; Chow group; Galois cohomology
Language: English
Document Type: Regular paper
Affiliations: 1: Department of Mathematics and Mechanics, St. Petersburg State University, Petrodvorets, 198904, Russia. e-mail: oleg@izh.usr.pu.ru 2: Westfälische Wilhelms-Universität, Mathematisches Institut, Einsteinstraße 62, D-48149 Münster, Germany. e-mail: karpenk@math.uni-muenster.de

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