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Presentation of

  1. Jun 5, 2012 #1
    proove that
    < x0 , x1 , . . . | [xi , xj ] = 1, i, j, ∈ N_0 ; x0^p = 1 ; (xi) ^ (p ^ i) = x0 , i ∈ N > is not presentation of Prüfer group
     
  2. jcsd
  3. Jun 5, 2012 #2

    Please do learn quickly how to type in LaTeX in this site: https://www.physicsforums.com/showthread.php?t=546968

    I'll try to edit your post (and, perhaps, address it):

    Prove (please, of course), that [tex]\langle x_0,x_1,...\,\,|\,\,[x_i,x_j]=1\,,\,i,j\in\mathbb{N}\,,\,x_0^p=1\,,\,x_i^{p^i}=x_0\,,\,i\in\mathbb{N}\rangle[/tex] is not a presentation of the Prüfer group.

    Now, the Prüfer group must fulfill the conditions [itex]\,x^p_i=x_{i-1}\,,\,i=1,2,3,...\,[/itex], but by your definition we'd have [tex]x_1^p=x_0\,,\,x_2^{p^2}=x_0=x_1^p\Longrightarrow [/tex]and I can't see how we can deduce from this that [itex]\,x_2^p=x_1\,[/itex] , as we're not sure we can take [itex]p-th[/itex] roots...

    Another possible approach: to show that an epimorphism from an infinitely generated abelian free sugroup to one of the groups is not the same for the other one...

    DonAntonio
     
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