Expressing Transpositions as Products of Adjacent Transpositions

In summary, the conversation discusses the task of showing that every transposition in Sn can be expressed as a product of adjacent transpositions, and specifically asks for the transposition (1,9) to be expressed in this form. The conversation also suggests working through a specific example and clarifies the definition of an adjacent transposition as a cycle like (1,2).
  • #1
murps232
1
0

Homework Statement



Show that every transposition (i,j)(1≤i≤j≤n) in Sn is expressible as a product of adjacent transpositions.

Also express the transposition (1,9) as a product of adjacent transpositions.

Homework Equations



none

The Attempt at a Solution


Really struggling to even start the proof.

Is the transposition (1,9)=(1,2)(2,3)(3,4)(4,5)(5,6)(6,7)(7,8)(8,9)?
 
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  • #2
I assume (i, j) means swapping i and j. You can check your answer if you have 9 small pieces of paper. That should also lead you on to a proof.

You are definitely on the right way that you have to "string" i through i + 1, i + 2, ... until it reaches j and vice versa.
 
  • #3
I suggest you start by working a specific example. Express (1,3) as the product of "adjacent transpositions". By the way, what is the definition of an "adjacent transposition"? A cycle like (1,2) ?
 

What is an Adjacent Transposition?

An adjacent transposition is a type of permutation in which two adjacent elements in a sequence are swapped. For example, in the sequence [1, 2, 3, 4], an adjacent transposition would result in [1, 3, 2, 4].

What is the significance of Adjacent Transpositions in mathematics?

Adjacent transpositions are often used in mathematical proofs, particularly in the field of group theory. They can help to simplify complex mathematical expressions and demonstrate certain properties of groups and permutations.

What is the Adjacent Transpositions proof?

The Adjacent Transpositions proof is a mathematical proof that demonstrates the existence of the alternating group, which is a subgroup of the symmetric group. This proof uses the concept of adjacent transpositions to show that every permutation can be decomposed into a product of adjacent transpositions.

How does the Adjacent Transpositions proof work?

The proof begins by showing that any permutation can be written as a product of adjacent transpositions. Then, by using the properties of adjacent transpositions and their inverses, it is shown that this product is unique. This proves that every permutation can be decomposed into a unique product of adjacent transpositions, which is a key property of the alternating group.

What are some real-world applications of the Adjacent Transpositions proof?

The Adjacent Transpositions proof has applications in fields such as cryptography, where it is used to generate secure encryption algorithms. It is also used in computer science and data analysis to efficiently manipulate and analyze large sets of data.

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