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Thread: Normal subgroup

  1. May 4th 2010, 08:34 AM #1
    cvcv49
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    Normal subgroup

    An Normal subgroup of Sn?
    why??
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  2. May 4th 2010, 08:37 AM #2
    tonio
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    Quote Originally Posted by cvcv49 View Post
    An Normal subgroup of Sn?
    why??

    Proof 1: because [S_n:A_n]=2 ;

    Proof 2: because \pi^{-1}\sigma\pi\in A_n\,\,\,\forall\,\pi\in S_n\,\,\forall \sigma\in A_n

    Tonio
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  3. May 6th 2010, 07:36 AM #3
    FancyMouse
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    And also a trivial one and S_n itself
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