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#1 Help Me ! » normal subgroups » 2011-03-30 09:41:32

ctmathnut
Replies: 1

Let G be a group with subgroups K and H where H is cyclic, H is normal in G and K is normal in H. Show that K is normal in G.

We want to show that gkg^(-1) ∈ K for all k ∈ K and g ∈ G. I know gkg^(-1)=gh^nkh^(-n)g^(-1) where h^n=1. I know the solution probably involves some combination of those elements but I can't quite see how. Does anyone have a clearer idea?

Thanks!

#2 Re: Help Me ! » Group Theory: Symmetric group and Alternating group » 2011-03-06 03:20:10

Does anyone have any ideas on this? It would be really helpful.

#3 Help Me ! » Group Theory: Symmetric group and Alternating group » 2011-02-24 10:54:45

ctmathnut
Replies: 2

I am in an Abstract Algebra course in graduate school and am trying to prove that the symmetric group S_4 is isomorphic to a subgroup of the alternating group A_6.
I am thinking that I need to find an isomorphism between the two. It is easy to find a map that takes all the even elements of S_4 into A_6, but I am having trouble mapping the odd elements.

Thank you!

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