Solving the Group Theory Conundrum: Proving 'a' is in Z(G)".

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Discussion Overview

The discussion revolves around a problem in group theory concerning the element 'a' of order 2 in a group G and whether it belongs to the center Z(G). Participants explore related concepts, including group homomorphisms and properties of group elements.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant notes that if every element of G has order 2, showing that 'a' is in Z(G) is straightforward, but this is not the case here.
  • Another participant questions the implications of the expression xax^-1 and its order, suggesting that it is 2.
  • A later reply asserts that since 'a' is the only element of order 2, it follows that xax^-1 must equal 'a', leading to the conclusion about 'a' being in Z(G).
  • Additionally, a new problem involving a group homomorphism f from Zm to Zn is introduced, with a focus on the condition that m and n are relatively prime.
  • One participant proposes using the relation (m,n)=1 to show that f is identically 0, but another challenges this by stating that the relation does not assist in the current context.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the properties of 'a' and the homomorphism problem. The discussion remains unresolved regarding the latter problem, as participants have not reached a consensus on how to proceed.

Contextual Notes

There are limitations in the discussion regarding the assumptions about the properties of group elements and the application of the relation involving m and n in the homomorphism context.

Who May Find This Useful

This discussion may be of interest to students and practitioners of group theory, particularly those exploring properties of group elements and group homomorphisms.

astronut24
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i've just started out with a course in group theory...here's a question that's been bothering me for a while now...
let G be a group and 'a' ,a unique element of order 2 in G. show that a belongs to Z(G).
if every element of the group has order 2 this is pretty easy...but that's not the case. one thing I've noted is a = a^-1..but does that help?
 
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Given any x in G, what can be said about xax^-1? For example, what is its order?
 
another question...

well...thanks...the order of xax^-1 is 2...and a is the only element with order 2...so xax^-1=a and that implies the result.
another problem that i seem to be unable to figure out is...
f:(Zm , +m) --> (Zn,+n) is a group homomorphism where Zm and Zn denote groups of residue classes modulo m and n respectively. if m and n are relatively prime, then show that f is identically 0.
i fathom we are supposed to use the relation... (m,n)=1 implies am+bn =1 for some a and b in Z...how do you proceed further?
thanks for the help...
 
Lemma: if f is a group homomorphism from G to H then the order of f(g) divides the order of g

Prove it and deduce the answer you want.

the am+bn=1 won't help since you aren't actually doing anything with m and n together.
 

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