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On a set of normal subgroups
Published online by Cambridge University Press: 18 May 2009
Extract
The commutator [a, b] of two elements a and b in a group G satisfies the identity
ab = ba[a, b].
The subgroups we study are contained in the commutator subgroup G′, which is the subgroup generated by all the commutators.
The group G is covered by a well-known set of normal subgroups, namely the normal closures {g}G of the cyclic subgroups {g} in G. In a similar way one may associate a subgroup K(g) with each element g, by defining K(g) to be the subgroup generated by the commutators [g, x] as x takes all values in G. These subgroups generate G′ (but do not cover G′ in general), and are normal in G in consequence of the identical relation
(A) [g, x]Y = [g, y]−1[g, xy]
holding for all g, x and y in G. (By ab we mean b−1ab.) It is easy to see that
{g}G = {g, K(g)}.
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- Research Article
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- Copyright © Glasgow Mathematical Journal Trust 1962
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