Suppose that a finite group G admits a Frobenius group of automorphisms
FH with kernel F and complement H such that the fixed-point subgroup of
F is trivial: CG(F)=1. In this situation various properties of G are
shown to be close to the corresponding properties of CG(H). By using
Clifford's theorem it is proved that the order ∣G∣ is bounded in terms of
∣H∣ and ∣CG(H)∣, the rank of G is bounded in terms of ∣H∣ and the rank
of CG(H), and that G is nilpotent if CG(H) is nilpotent. Lie ring
methods are used for bounding the exponent and the nilpotency class of G in
the case of metacyclic FH. The exponent of G is bounded in terms of ∣FH∣
and the exponent of CG(H) by using Lazard's Lie algebra associated with the
Jennings--Zassenhaus filtration and its connection with powerful subgroups. The
nilpotency class of G is bounded in terms of ∣H∣ and the nilpotency class
of CG(H) by considering Lie rings with a finite cyclic grading satisfying a
certain `selective nilpotency' condition. The latter technique also yields
similar results bounding the nilpotency class of Lie rings and algebras with a
metacyclic Frobenius group of automorphisms, with corollaries for connected Lie
groups and torsion-free locally nilpotent groups with such groups of
automorphisms. Examples show that such nilpotency results are no longer true
for non-metacyclic Frobenius groups of automorphisms.Comment: 31 page