Proving Aut(S_3) is Isomorphic to S_3

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SUMMARY

Aut(S_3) is isomorphic to S_3, as both groups have exactly six elements. The group S_3, representing the symmetric group on three elements, is non-abelian, which distinguishes it from the cyclic group Z_6, also of order six. To prove the isomorphism, one must demonstrate that there are exactly six isomorphisms and identify at least one pair that do not commute. The relation (12)(13)=(132) is a key aspect in establishing the non-commutative nature of S_3.

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  • Understanding of group theory concepts, specifically symmetric groups.
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  • Knowledge of permutation notation and operations.
  • Basic understanding of abelian and non-abelian groups.
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  • Study the properties of symmetric groups, focusing on S_3 and its structure.
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  • Explore the differences between abelian and non-abelian groups.
  • Investigate the concept of group actions and their implications in automorphisms.
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happyg1
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Homework Statement




Prove that Aut(S_3)=S_3

Homework Equations


= means isomorphic


The Attempt at a Solution



If I let S_3 be {1,2,3} then I can write out explicitly its 6 elements...the permutations of 1,2,3...
Aut(S3) is the set of isomorphisms of S3 onto itself. So can I just write them all out and then say that since they have the same order they are isomorphic?
Or is there a better way?

Thanks,
CC
 
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If you can show there are exactly 6 isomorphisms, then you've shown Aut(S_3) is one of the two groups of order 6: Z_6 and S_3. These can be distinguished by the fact that Z_6 is abelian while S_3 is not, so it only remains to find a pair of isomorphisms that don't commute.

How were you planning on showing there are exactly 6 isomorphisms? If you're not sure here, think about the relation:

(12)(13)=(132)
 
happyg1 said:
Aut(S3) is the set of isomorphisms of S3 onto itself. So can I just write them all out and then say that since they have the same order they are isomorphic?

No. This does not prove anything.
 

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