How Does Conjugation Affect Cycles in Permutations?

In summary, to show that P(i1i2...ir)P-1 = (P(i1)P(i2)...P(ir)), it is sufficient to prove that it holds for cycles. Let C = (im1im2...imk) and D = (i1i2...ir). By definition of a cycle, we have imk\stackrel{C^{-1}}{\rightarrow}imk-1\stackrel{D}{\rightarrow}imk-1+1\stackrel{C}{\rightarrow}imk+1. Let D` = (C(i1)C(i2)...C(ir)). Then, imk\stackrel{D`}{\rightarrow}im
  • #1
ForMyThunder
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Homework Statement



Let P be a permutation of a set. Show that P(i1i2...ir)P-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,

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{}{\rightarrow}[/tex]imk+1

I don't know how to prove this last part, nor do I know if my reasoning is correct. Any suggestions?
 
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  • #2
Hi ForMyThunder! :smile:

Hint: what is P-1(P(i1)) ? :wink:
 

FAQ: How Does Conjugation Affect Cycles in Permutations?

What is a permutation?

A permutation is a rearrangement of objects or elements in a specific order. It is a way of arranging a set of objects in a specific sequence.

How is a permutation different from a combination?

A permutation involves arranging objects in a specific order, while a combination does not consider the order. In other words, the order in which the elements are arranged matters in a permutation, but not in a combination.

What is a cycle in permutation?

A cycle in permutation is a specific type of rearrangement where some elements are moved to different positions while others remain in their original positions. This creates a circular pattern of movement within the permutation.

How many possible permutations can be made from a set of n elements?

The number of possible permutations from a set of n elements is n factorial (n!). This means that for every element in the set, there are n-1 possible positions, and the total number of permutations is the product of all these positions, starting from n and decreasing by 1 until 1 is reached.

How can permutations be used in real-life applications?

Permutations are used in various fields such as mathematics, computer science, and statistics. In real-life, they can be used to determine the number of distinct arrangements or combinations of items, such as in lottery games, seating arrangements, and password combinations. They are also used in cryptography to create secure codes and in genetics to analyze DNA sequences.

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