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Prove not isomorphic?

  1. Oct 9, 2008 #1
    how would you go about showing that a subgroup and dihedral group- of the same order- are not isomorphic?
     
  2. jcsd
  3. Oct 10, 2008 #2
    Counterexample.
     
  4. Oct 10, 2008 #3

    HallsofIvy

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    Sub group of WHAT? The "dihedral group" of a specified order is the reflection and rotations group of a polygon but you would have to say what subgroup, of what group you want to show is not isomorphic to that. I imagine there must exist SOME subgroup, of SOME group, that is isomorphic to a dihedral group. Did you mean to say, "show that a subgroup of a dihedral group cannot be isomorphic to another dihedral group"?
     
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