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Automorphisms of free nilpotent-by-abelian groups

Published online by Cambridge University Press:  24 October 2008

R. M. Bryant
Affiliation:
University of Manchester Institute of Science and Technology, Manchester M60 1QD
C. K. Gupta
Affiliation:
University of Manitoba, Winnipeg R3T 2N2, Canada

Extract

Let Fn be a free group of finite rank n with basis {x1,…, xn}. Let be a variety of groups and write for the verbal subgroup of Fn corresponding to . (See [11] for information on varieties and related concepts.) Every automorphism of Fn induces an automorphism of the relatively free group Fn/V, and those automorphisms of Fn/V arising in this way are called tame. If is the variety of all metabelian groups and n ╪ 3 then every automorphism of Fn/V is tame [2, 4, 12]. But this is an exceptional situation. For many (and probably most) other varieties , Fn/V has non-tame automorphisms for all sufficiently large n. This holds for the variety of all nilpotent groups of class at most c where c ≥ 3 [1, 3] and for nearly all product varieties including, in particular, the variety of all groups whose derived groups are nilpotent of class at most c, where c > 2 [10, 13].

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 1993

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References

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