Can a Group Have a Cyclic Automorphism Group of Odd Order?

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SUMMARY

No group can have its automorphism group cyclic of odd order, with the exception of the trivial case of the group Z/2Z. The discussion highlights that while Aut(Z/2Z) has order 1, which is odd, this case is considered trivial. The main task is to demonstrate that every other group with a cyclic automorphism group must possess an automorphism of order 2, thereby confirming the impossibility of having a cyclic automorphism group of odd order for non-trivial groups.

PREREQUISITES
  • Understanding of group theory concepts, specifically automorphism groups.
  • Familiarity with cyclic groups and their properties.
  • Knowledge of Z/2Z and its significance in group theory.
  • Basic proof techniques in abstract algebra.
NEXT STEPS
  • Study the properties of automorphism groups in finite groups.
  • Learn about the structure of cyclic groups and their orders.
  • Explore examples of groups with automorphism groups of various orders.
  • Investigate the implications of automorphisms of order 2 in group theory.
USEFUL FOR

Students of abstract algebra, particularly those studying group theory and automorphisms, as well as educators looking to clarify concepts related to cyclic groups and their automorphism properties.

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Homework Statement



Prove that no group can have its automorphism group cyclic of odd order.

Homework Equations





The Attempt at a Solution



Aut(Z2) has order 1, which is odd...trivial, yes, but I thought I was DONE.

However, my professor has said "well prove it EXCEPT for Z2"

I thought I was done, and now I have till 2 to do redo this and I have a mental block on it.

Can someone give my a push?

Thanks,
CC
 
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So you've got to show that every group (except Z/2Z) with cyclic aut. grp. has an automorphism of order 2...
 
All right, I think I see it now...although I already turned it in incomplete. I just couldn't see it yesterday.
Thanks.
 

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