Automorph-permutable not implies permutable: Difference between revisions
(New page: {{subgroup property non-implication| stronger = automorph-permutable subgroup| weaker = permutable subgroup}} ==Statement== ===Verbal statement=== An automorph-permutable subgroup o...) |
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==Facts used== | ==Facts used== | ||
* [[Symmetric groups are complete]]: For <math>n \ne 2,6</math>, the symmetric group on <math>n</math> letters is complete: it is centerless and every automorphism of it is inner. | * [[Symmetric groups on finite sets are complete]]: For <math>n \ne 2,6</math>, the symmetric group on <math>n</math> letters is complete: it is centerless and every automorphism of it is inner. | ||
==Proof== | ==Proof== | ||
Latest revision as of 18:17, 5 April 2009
This article gives the statement and possibly, proof, of a non-implication relation between two subgroup properties. That is, it states that every subgroup satisfying the first subgroup property (i.e., automorph-permutable subgroup) need not satisfy the second subgroup property (i.e., permutable subgroup)
View a complete list of subgroup property non-implications | View a complete list of subgroup property implications
Get more facts about automorph-permutable subgroup|Get more facts about permutable subgroup
EXPLORE EXAMPLES YOURSELF: View examples of subgroups satisfying property automorph-permutable subgroup but not permutable subgroup|View examples of subgroups satisfying property automorph-permutable subgroup and permutable subgroup
Statement
Verbal statement
An automorph-permutable subgroup of a group need not be permutable.
Facts used
- Symmetric groups on finite sets are complete: For , the symmetric group on letters is complete: it is centerless and every automorphism of it is inner.
Proof
Example in the symmetric group on four letters
Consider to be the symmetric group on four letters: . Consider the two-element subgroup generated by the double transposition .
is an automorph-permutable subgroup in : Since symmetric groups are complete, it suffices to argue that is conjugate-permutable in . This, in turn follows because is a 2-subnormal subgroup of : it is normal in the subgroup , which is normal in .
On the other hand, is not permutable in , for instance, does not permute with the subgroup generated by .