Does the Product of Cycles Hold for Permutations?

In summary, the conversation discusses showing that the equation P(i1i2...ir)B-1 = (P(i1)P(i2)...P(ir)) holds for permutations of a set. The solution involves proving this for cycles, and using the notation C = (im1im2...imk) and D = (i1i2...ir). The conversation also includes an example of evaluating the equation for P(i1,i2,...ir)P^(-1)P(i1).
  • #1
ForMyThunder
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Homework Statement



Let P be a permutation of a set. Show that P(i1i2...ir)B-1 = (P(i1)P(i2)...P(ir))


Homework Equations



N/A

The Attempt at a Solution



Since P is a permutation, it can be written as the product of cycles. So I figured that showing that the above equation holds for cycles will be sufficient to show that it holds for all permutations.

Let C = (im1im2...imk) be a cycle and let D = (i1i2...ir). Then, for mk [tex]\neq[/tex] r,

imk[tex]\stackrel{C^{-1}}{\rightarrow}[/tex]imk-1[tex]\stackrel{D}{\rightarrow}[/tex]imk-1+1[tex]\stackrel{C}{\rightarrow}[/tex]imk+1

Let D` = (C(i1)C(i2)...C(ir)), then imk[tex]\stackrel{}{D`\rightarrow}[/tex]imk+1
 
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  • #2
I accidentally made two threads. Just ignore this one.
 
  • #3
Well, for example (P(i1)P(i2)...P(ir)) maps P(i1) to P(i2). You want to show P(i1,i2,...ir)P^(-1) does the same thing. Try it. Evaluate P(i1,i2,...ir)P^(-1)P(i1).
 

1. What is a permutation?

A permutation is an arrangement of objects where the order matters. It is a way of rearranging a set of elements in a specific order.

2. What is the difference between a permutation and a combination?

A permutation involves arranging objects in a specific order, while a combination does not take into account the order of the objects. In other words, a permutation is about the arrangement of elements, while a combination is about the selection of elements.

3. What are cycles in permutations?

Cycles are a way of representing permutations in a compact form. They consist of elements that are moved to their respective new positions in the permutation. For example, the permutation (1 2 3 4) can be represented as (1 2)(2 3)(3 4). This means that element 1 is moved to position 2, element 2 is moved to position 3, and so on.

4. How do you calculate the number of possible permutations?

The number of possible permutations of a set with n elements is given by n!, which is read as "n factorial". This means that for a set with 4 elements, there are 4! = 4x3x2x1 = 24 possible permutations.

5. How are permutations used in real life?

Permutations have various applications in fields such as mathematics, statistics, computer science, and cryptography. They are used to solve problems involving arrangements, patterns, and codes. For example, in computer science, permutations are used to generate unique combinations of characters for encryption purposes.

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