Disjoint cycles in permutations

In summary, the purpose of writing disjoint cycles is to efficiently represent and manipulate permutations. This is achieved by breaking down a permutation into smaller, simpler parts. To write a disjoint cycle, elements are mapped to each other in a cycle. Disjoint cycles cannot overlap or intersect, as this would result in multiple mappings for some elements. Operations on disjoint cycles can be performed using cycle notation. Disjoint cycles are significant in group theory, as they provide a concise representation of permutations and aid in understanding the structure and properties of groups.
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RJLiberator
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Homework Statement



Screen Shot 2016-03-26 at 3.57.24 PM.png

Homework Equations

The Attempt at a Solution

My answers for the disjoint cycles of f,g,h,k are as follows. My question concerns my disjoint cycles for g. Are we allowed to have 3 cycles? I would think "yes" because that just makes sense to me.

for f: ( 1 3 8 4 6) (2 5)
g: (2 6 7) (3 8) (4 5)
h: (1 8 7 3 5 2) (4 6)
k: (1 5 4) (2 3 8)

For orders:

order f: lcm(5, 2) = 10
order g: lcm ( 3, 2) = 6
order h: lcm(6, 2) = 6
order k: lcm(3, 3) = 3
 
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  • #2
Also, if I wanted to write f as a product of transpositions I would take:
f = (1 3 8 4 6) (2 5)
product of transpositions: (1,3)(3,8)(8,4)(4,6)(2,5)
5 total so odd permutation
 

1. What is the purpose of writing disjoint cycles?

The purpose of writing disjoint cycles is to efficiently represent and manipulate permutations, which are mathematical tools used to describe the rearrangement of a set of objects. Disjoint cycles are a way to break down a permutation into smaller, simpler parts, making it easier to analyze and perform operations on.

2. How do you write a disjoint cycle?

To write a disjoint cycle, you start with a set of elements and then map each element to another element in the set. This mapping is represented by an arrow, and the elements are connected in a cycle. The cycle ends when you reach the original element. Multiple disjoint cycles can be written to describe a larger permutation.

3. Can disjoint cycles overlap or intersect?

No, disjoint cycles cannot overlap or intersect. This is because each element in the set can only be mapped to one other element in the cycle. If there were overlapping or intersecting cycles, it would result in multiple mappings for some elements, which would violate the definition of a permutation.

4. How do you perform operations on disjoint cycles?

To perform operations on disjoint cycles, you can use a technique called cycle notation. In this notation, disjoint cycles are written as a product of smaller cycles, and operations such as composition and inverse can be performed by manipulating the cycles. For example, the product of two disjoint cycles is equal to the composition of the individual cycles.

5. What is the significance of disjoint cycles in group theory?

Disjoint cycles play a crucial role in group theory, specifically in the theory of permutation groups. They allow for a more concise and efficient representation of permutations, which are a fundamental concept in group theory. Disjoint cycles also help in understanding the structure and properties of groups, as well as in solving problems related to symmetry and transformations.

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