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finitely generated group (Definition)

A finitely generated group is a group that has a finite generating set.

Every finite group is obviously finitely generated. Every finitely generated group is countable.

Any quotient of a finitely generated group is finitely generated. However, a finitely generated group may have subgroups that are not finitely generated. (For example, the free group of rank $ 2$ is generated by just two elements, but its commutator subgroup is not finitely generated.) Nonetheless, a subgroup of finite index in a finitely generated group is necessarily finitely generated; a bound on the number of generators required for the subgroup is given by the Schreier index formula.

The finitely generated groups all of whose subgroups are also finitely generated are precisely the groups satisfying the maximal condition. This includes all finitely generated nilpotent groups and, more generally, all polycyclic groups.

A group that is not finitely generated is sometimes said to be infinitely generated.



"finitely generated group" is owned by yark. [ full author list (2) | owner history (1) ]
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See Also: fundamental theorem of finitely generated abelian groups, A finitely generated group has only finitely many subgroups of a given index

Also defines:  finitely generated, finitely generated subgroup, infinitely generated, infinitely generated group, infinitely generated subgroup
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Cross-references: polycyclic groups, nilpotent groups, maximal condition, number, index, commutator subgroup, generated by, rank, free group, subgroups, countable, finite group, generating set, group
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This is version 21 of finitely generated group, born on 2002-02-03, modified 2007-06-14.
Object id is 1726, canonical name is FinitelyGenerated.
Accessed 10441 times total.

Classification:
AMS MSC20A05 (Group theory and generalizations :: Foundations :: Axiomatics and elementary properties)

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