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permutable subgroup (Definition)

Let $G$ be a group. A subgroup $H$ of $G$ is said to be permutable if it permutes with all subgroups of $G$ , that is, $KH=HK$ for all $K\leq G$ . We sometimes write $H\per G$ to indicate that $H$ is a permutable subgroup of $G$ .

Permutable subgroups were introduced by Øystein Ore, who called them quasinormal subgroups.

Normal subgroups are clearly permutable.

Permutable subgroups are ascendant. This is a result of Stonehewer[1], who also showed that in a finitely generated group, all permutable subgroups are subnormal.

References

1
Stewart E. Stonehewer, Permutable subgroups of infinite groups, Math. Z. 125 (1972), 1-16. (This paper is available from GDZ.)




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Other names:  quasinormal subgroup, quasi-normal subgroup
Also defines:  permutable, quasinormal, quasi-normal

Attachments:
example of non-permutable subgroup (Example) by Algeboy
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Cross-references: subnormal, finitely generated group, ascendant, normal subgroups, subgroup, group
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This is version 6 of permutable subgroup, born on 2006-09-17, modified 2008-11-23.
Object id is 8372, canonical name is PermutableSubgroup.
Accessed 4271 times total.

Classification:
AMS MSC20E07 (Group theory and generalizations :: Structure and classification of infinite or finite groups :: Subgroup theorems; subgroup growth)

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