On the normalizer of finitely generated subgroups of absolute galois groups of uncountable hilbertian fields of characteristic 0
Author(s) -
Wulf-Dieter Geyer,
Moshe Jarden
Publication year - 1988
Publication title -
israel journal of mathematics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.168
H-Index - 63
eISSN - 1565-8511
pISSN - 0021-2172
DOI - 10.1007/bf02778037
Subject(s) - mathematics , uncountable set , centralizer and normalizer , countable set , cardinality (data modeling) , algebraically closed field , combinatorics , complement (music) , discrete mathematics , pure mathematics , biochemistry , chemistry , complementation , computer science , gene , data mining , phenotype
For a fieldK and a positive integere let N e (K) be the set of alle-tuplesσ = (σ 1, …,σ e)εG(K) e that generate a selfnormalizer closed subgroup ofG(K). Chatzidakis proved, that ifK is Hilbertian and countable, then N e (K) has Haar measure 1. IfK is Hilbertian and uncountable, this need not be the case. Indeed, we prove that ifK 0 is a field of characteristic 0 that contains all roots of unity,T is a set of cardinality ℵ1 which is algebraically independent overK 0 andK =K 0(T), then neither N e (K) nor its complement contain a set of positive measure. In particular N e (K) is a nonmeasurable set.
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