Proving Commutativity in Groups with a^2 = e for all a in G

In summary, the conversation is discussing how to show that if a^2 = e for all a in G, then G must be commutative (where e is the identity). The conversation goes on to clarify that this means ab = ba for all elements a and b in G. It is explained that aabb = abab, so aabb must also equal e. The final comment confirms understanding and suggests to finish the proof from there.
  • #1
margaret23
11
0
Could you also help me start this question

show that if a^2 = e for all a in G then G must be commutative. (where e is the identity)

thanks
 
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  • #2
What does aabb equal? What does abab equal?
 
  • #3
umm ok .. so i get that aabb must also =e .. but I am not sure how to get abab
 
Last edited:
  • #4
margaret23 said:
umm ok .. so i get that aabb must also =e .. but I am not sure how to get abab

Just show that ab = ba.

That's what you're doing. Start from there.
 
  • #5
margaret23 said:
umm ok .. so i get that aabb must also =e .. but I am not sure how to get abab
It's (ab)(ab), so you know aabb = abab. Can you finish that?
 
  • #6
thanks :).. i got it now
 

1. What is group theory?

Group theory is a branch of mathematics that studies the algebraic structures known as groups. A group is a set of elements with a binary operation (usually denoted as *) that satisfies four axioms: closure, associativity, identity, and invertibility. These structures are used to study symmetry, patterns, and relationships between objects.

2. What are the applications of group theory?

Group theory has various applications in different fields such as physics, chemistry, computer science, and cryptography. In physics, group theory is used to describe the symmetries of physical systems. In chemistry, it is applied to molecular orbital theory and crystallography. In computer science, group theory is used in the design and analysis of algorithms. In cryptography, it is used to create secure encryption methods.

3. What is the significance of the identity element in a group?

The identity element is an element in a group that when combined with any other element in the group using the binary operation, results in the same element. In other words, the identity element acts like a neutral element and does not change the value of the element it is combined with. The identity element is essential in defining the structure and properties of a group.

4. What is the difference between a group and a subgroup?

A subgroup is a subset of a group that satisfies the four axioms of a group. In other words, a subgroup is a smaller group within a larger group. The elements and binary operation of the subgroup are inherited from the larger group. However, a subgroup may have additional properties that the larger group does not have, making it a distinct entity.

5. How is group theory related to symmetry?

Group theory is closely related to symmetry as it provides a mathematical framework for studying and understanding symmetries. In group theory, symmetries are represented as transformations that preserve the structure of a group. For example, rotation, reflection, and translation are all symmetries that can be described using group theory. This allows for a more systematic and rigorous approach to studying and classifying symmetries.

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