Galois actions of finitely generated groups rarely have model companions

Abstract

AbstractWe show that if is a finitely generated group such that its profinite completion is “far from being projective” (i.e., the kernel of the universal Frattini cover of is not a small profinite group), then the class of existentially closed ‐actions on fields is not elementary. Since any infinite, finitely generated, virtually free, and not free group is “far from being projective,” the main result of this paper corrects an error in our paper, Beyarslan and Kowalski (Proc. London Math. Soc., (2) 118 (2019), 221–256), by showing the negation of Theorem 3.26 in that paper.