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Groups of Wielandt length two

Published online by Cambridge University Press:  24 October 2008

Elizabeth A. Ormerod
Affiliation:
The Australian National University, G.P.O. Box 4, Canberra A.C.T. 2601, Australia

Extract

The Wielandt subgroup ω(G) of a group G is the subgroup of elements that normalize every subnormal subgroup of G. This subgroup, now named for Wielandt, was introduced by him in 1958 [15]. For a finite non-trivial group the Wielandt subgroup is always a non-trivial, characteristic subgroup. Thus it is possible to define the ascending Wielandt series for a finite group G which terminates at the group. Write ω0(G) = 1, and for i ≥ 1, ωi(G)/ωi–1(G) = ω(Gi–1(G)). The smallest n such that ωn(G) = G is called the Wielandt length of G, and the class of groups of Wielandt length at most n is denoted by . From the definition it follows that is closed under homomorphic images and taking normal subgroups. Nilpotent groups in are also closed under taking subgroups.

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 1991

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