Does o(ab)=lcm(o(a),o(b)) for Group G Elements a & b?

In summary, the equation "o(ab)=lcm(o(a),o(b))" represents the order of the product of two elements in a group, which is equal to the least common multiple of the orders of the individual elements. This equation can be applied to all finite groups and has many uses, such as finding the order of a product, proving properties of groups, and solving problems involving group elements. However, there are exceptions to this equation, such as in non-commutative groups or when the orders of the elements are relatively prime.
  • #1
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Suppose G is a group, a,b are two elements of G, does o(ab)=lcm(o(a),o(b))?
o(ab) denotes the order of ab, lcm(o(a),o(b)) denotes the Least Common Multiple of o(a) & o(b).
 
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  • #2
It is true when a and b commute, and can easily be proven in that case.
When a and b do not commute, the statement is false. For a counterexample, you could try to find some elements in S3 (e.g. there are elements a and b such that o(a) = 2, o(b) = 3, o(a, b) = 2).
 

FAQ: Does o(ab)=lcm(o(a),o(b)) for Group G Elements a & b?

What does "o" stand for in "o(ab)=lcm(o(a),o(b))"?

In this equation, "o" stands for the order of an element in a group. The order of an element is the smallest positive integer n such that a^n equals the identity element of the group.

What is the significance of the equation "o(ab)=lcm(o(a),o(b))" for group elements a and b?

This equation shows that the order of the product of two elements, ab, is equal to the least common multiple of the orders of the individual elements a and b. This is a useful property in understanding the structure and properties of groups.

Can this equation be applied to all groups?

Yes, this equation can be applied to all groups, as long as the group is finite. In infinite groups, the concept of order may not apply or may have a different definition, so this equation may not hold true.

How can this equation be used in solving problems involving group elements?

This equation can be used to find the order of a product of two elements, given the orders of the individual elements. It can also be used to prove properties of groups, such as the closure property, where the product of two elements in a group is also an element in the group.

Are there any exceptions to the equation "o(ab)=lcm(o(a),o(b))"?

Yes, there are exceptions. This equation only holds true for groups with elements that commute, meaning the order of ab is equal to the order of ba. In non-commutative groups, this equation may not hold true. Additionally, if the orders of a and b are relatively prime, then the equation simplifies to o(ab) = o(a)o(b), but this is not always the case.

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