Results 1 to 2 of 2

Thread: Character Theory II

  1. #1
    Junior Member
    Joined
    Oct 2010
    Posts
    49

    Character Theory II

    Urgent answer required for these questions please!

    (3) Let G be a finite group and let element a in Aut(G) be an automorphism og G. Let X be an element of Irr(G) be an irreducible character of G.
    Define (X)^a(g) := X(g^a). Is (X)^a irreducible?
    Last edited by Ackbeet; May 11th 2011 at 01:00 PM. Reason: Splitting threads.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor Drexel28's Avatar
    Joined
    Nov 2009
    From
    College Park, Maryland
    Posts
    4,542
    Thanks
    11
    Quote Originally Posted by Turloughmack View Post
    Urgent answer required for these questions please!

    (3) Let G be a finite group and let element a in Aut(G) be an automorphism og G. Let X be an element of Irr(G) be an irreducible character of G.
    Define (X)^a(g) := X(g^a). Is (X)^a irreducible?
    Think back to what irreducible characters are--they are the characters of irreps on G. So, let \chi\in\text{irr}(G) and let \rho:G\to\text{GL}\left(V\right) be the irrep it came from. Then, as you can easily verify \chi^a as you denoted is the character of \rho\circ a:G\to\text{GL}(V) (which is a representation since a\in\text{End}(G)). Now, if \rho\circ a left any non-trivial proper subspace of V \rho\circ a-invariant wouldn't it be necessary (using the fact that a is bijective) that same subspace would be \rho-invariant? So...
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Character Theory
    Posted in the Advanced Algebra Forum
    Replies: 1
    Last Post: May 11th 2011, 05:34 PM
  2. Character/ Representation Theory
    Posted in the Advanced Algebra Forum
    Replies: 2
    Last Post: March 14th 2011, 04:00 PM
  3. Eight character passwords
    Posted in the Discrete Math Forum
    Replies: 2
    Last Post: May 16th 2010, 06:45 AM
  4. Easy character theory proof
    Posted in the Advanced Algebra Forum
    Replies: 1
    Last Post: April 4th 2010, 01:56 PM
  5. Character Theory of Finite Groups- Applications
    Posted in the Advanced Algebra Forum
    Replies: 0
    Last Post: April 3rd 2009, 11:25 AM

Search Tags


/mathhelpforum @mathhelpforum