Proving Abelianity in Groups with $g^{2} = 1$: A Simple Proof

  • MHB
  • Thread starter GreenGoblin
  • Start date
  • Tags
    Group Proof
In summary, in order to show that a group with $g^{2}=1$ for all $g$ is Abelian, we must prove that $gh=hg$ for any two elements $g,h$ in the group. A possible proof could start by assuming that $g^{2}=1$ for all $g$ in the group, and then showing that $(gh)^{2}=1$ and using this to show that $gh=hg$.
  • #1
GreenGoblin
68
0
I need to show a group with $g^{2} = 1$ for all g is Abelian. This is all the information given, I do know what Abelian is, and I know that this group is but I don't know how to 'show' it. Can someone help?

Gracias,
GreenGoblin
 
Physics news on Phys.org
  • #2
For a start, see this page from The Math Forum.
 
  • #3
I did the proof and it doesn't seem to be relevant that $g^{2}=1$. Just that it is the group of $g^{2}$. Is this right?
 
  • #4
For $$ g,h\in G $$ consider $$ (gh)^2=1 $$ then expand out and see what happens
 
  • #5
GreenGoblin said:
I did the proof and it doesn't seem to be relevant that $g^{2}=1$. Just that it is the group of $g^{2}$. Is this right?
I am not sure what "the group of $g^{2}$" means. Could you post your proof?
 
  • #6
I just showed algebraically gh = hg, without using the fact $(gh)^{2}=1$.
 
  • #7
perhaps you should show your proof.

it is not the case that all groups are abelian, only some groups are.

a typical proof starts out like this:

suppose $g^2 = 1$ for all g in G. let g, h be any two elements of G (which perhaps might be the same element, if |G| = 1).

then gh is an element of G, so

$(gh)^2 = 1$, that is:

ghgh = 1. then,

g(ghgh) = g(1) = g, and...?
 

FAQ: Proving Abelianity in Groups with $g^{2} = 1$: A Simple Proof

What is an Abelian group?

An Abelian group is a mathematical group in which the order of the elements does not affect the result of the group operation. This property is also known as commutativity, which means that for any two elements a and b in the group, a * b = b * a.

How do you prove that a group is Abelian?

To prove that a group is Abelian, you need to show that for any two elements a and b in the group, a * b = b * a. This can be done by performing the group operation on all possible combinations of elements and showing that the result is the same regardless of the order in which the elements are multiplied.

What are some examples of Abelian groups?

Some common examples of Abelian groups include the integers, rational numbers, and real numbers under addition, as well as the group of 2x2 matrices with real entries under matrix multiplication.

Can a non-Abelian group become Abelian?

No, a non-Abelian group cannot become Abelian. The property of commutativity is a fundamental characteristic of Abelian groups and cannot be changed. However, it is possible to create a new Abelian group from a non-Abelian group by defining a different group operation.

Why is it important to prove that a group is Abelian?

Proving that a group is Abelian can help in understanding the group's structure and properties. It can also make it easier to perform calculations and solve problems involving the group, as the commutative property simplifies many operations. Additionally, Abelian groups have many applications in various branches of mathematics and physics, making it important to be able to identify and work with them.

Similar threads

Replies
1
Views
958
Replies
1
Views
1K
Replies
2
Views
1K
Replies
5
Views
2K
Replies
3
Views
2K
Replies
1
Views
1K
Replies
2
Views
2K
Replies
3
Views
2K
Back
Top