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

In summary, to show that x^2≠y in a non-abelian group, we can choose distinct elements x and y such that xy≠yx and then show that if x^2≠1, then it cannot be equal to any of the elements e, x, y, xy, or yx. This can be proven by examining the implications of x^2=x, x^2=xy, and x^2=yx and showing that they all lead to contradictions. Additionally, we can use the fact that x does not commute with y to show that x^2 also cannot commute with y, providing further evidence that x^2≠y.
  • #1
gottfried
119
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?
 
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  • #2
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?
 
  • #3
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.
 
  • #4
x^2=y→x^3=xy and x^3=yx
 

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

1. What is group theory?

Group theory is a branch of mathematics that studies the properties and structures of groups. A group is a set of elements with a defined binary operation that follows certain rules, such as closure, associativity, identity, and invertibility.

2. What are the applications of group theory?

Group theory has many applications in various fields such as physics, chemistry, computer science, and cryptography. It is used to study symmetry, solve equations, classify molecules, and design secure communication systems.

3. What is a simply group?

A simply group, also known as a simple group, is a group that does not have any proper nontrivial normal subgroup. This means that the group cannot be broken down into smaller subgroups that preserve the group's structure. Simply groups are the building blocks of group theory and have important applications in algebraic geometry and number theory.

4. How do you solve a group theory problem?

To solve a group theory problem, you need to first understand the properties of groups and the given problem. Then, you can use various techniques such as group multiplication, coset decomposition, and Lagrange's theorem to simplify the problem and find a solution. It is also helpful to have a good understanding of basic abstract algebra concepts.

5. What are some common misconceptions about group theory?

One common misconception about group theory is that it is only applicable to abstract mathematical concepts and has no real-world applications. However, as mentioned earlier, group theory has many practical applications in various fields. Another misconception is that all groups are commutative, but there are many non-commutative groups that have important applications in physics and chemistry.

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