Can x^2 Equal y in a Non-Abelian Group?

Click For Summary

Homework Help Overview

The discussion revolves around properties of elements in a non-abelian group, specifically examining the implications of the equation x² = y under the condition that x and y are distinct elements and do not commute.

Discussion Character

  • Conceptual clarification, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the implications of assuming x² equals various elements, questioning how these assumptions lead to contradictions or reinforce the distinctness of x and y.

Discussion Status

Some participants have offered insights that help clarify the relationships between the elements, while others are still grappling with how to demonstrate that x² cannot equal y. There is an ongoing exploration of the properties of non-abelian groups and the implications of element interactions.

Contextual Notes

The problem is constrained by the requirement that x and y are distinct elements in a non-abelian group, and that x² is not equal to the identity element. There is a focus on the relationships and commutation properties of the elements involved.

gottfried
Messages
118
Reaction score
0

Homework Statement


Let (G,.) be an non-abelian group. Choose distinct x and y such that xy≠yx.

Show that if x2≠1 then x2[itex]\notin[/itex]{e,x,y,xy,yx}

The Attempt at a Solution



If x2=x would imply x.x.x-1=x.x-1 and x=e which cannot be.
If x2= xy or x2=yx would imply x=y which also cannot be.

How does one show that x2≠y?
 
Physics news on Phys.org
gottfried said:

Homework Statement


Let (G,.) be an non-abelian group. Choose distinct x and y such that xy≠yx.

Show that if x2≠1 then x2[itex]\notin[/itex]{e,x,y,xy,yx}

The Attempt at a Solution



If x2=x would imply x.x.x-1=x.x-1 and x=e which cannot be.
If x2= xy or x2=yx would imply x=y which also cannot be.

How does one show that x2≠y?

x doesn't commute with y. Does x commute with x^2?
 
Yes I believe it does so x2.x=x.x2 which would imply y.x=x.y if x2=y which is a contradiction.

Thanks for the help. You gave me just enough help to move forward with the problem but left some of the satisfaction of figuring it out to me which is cool, thanks.
 
x^2=y→x^3=xy and x^3=yx
 

Similar threads

  • · Replies 16 ·
Replies
16
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 16 ·
Replies
16
Views
2K
Replies
5
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 6 ·
Replies
6
Views
5K