Transpositions in Abstract Algebra

Click For Summary

Homework Help Overview

The discussion revolves around a theorem from abstract algebra regarding permutations in the symmetric group Sn and their representation as products of transpositions. The original poster questions the validity of the theorem when n is equal to 1, suggesting that an assumption such as n ≥ 2 should be included for clarity.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to understand the implications of the theorem when n=1 and questions whether the theorem's statement is meaningful in that case. Other participants explore the definition of an empty product and its relevance to the theorem.

Discussion Status

Participants are engaging in a discussion about the definitions and implications of the theorem. Some provide insights into the concept of an empty product, while others seek clarification on the applicability of the theorem for n=1. There is no explicit consensus reached, but the conversation is exploring different interpretations.

Contextual Notes

The discussion highlights a potential ambiguity in the theorem's statement regarding the value of n and its implications for the definition of transpositions. The original poster's concern about the lack of an assumption for n is a focal point of the conversation.

gotjrgkr
Messages
84
Reaction score
0

Homework Statement


Hi!
There's a theorem 7.43 in p.221(Hungerford's abstract algebra) which states that every permutation in S_{n} is a product of transpositions.
What I know about the concept of transposition is it is defined if there are at least two distinct elements. But, in the above theorem, there's no assumption to prevent that n could be 1. I think, in that case, saying a product of transpositions is meaningless.
So, I think an assumption such as n\geq2 must be added in the above theorem.
Am I wrong?? If so, could you explain why??

Homework Equations





The Attempt at a Solution

 
Physics news on Phys.org
gotjrgkr said:

Homework Statement


Hi!
There's a theorem 7.43 in p.221(Hungerford's abstract algebra) which states that every permutation in S_{n} is a product of transpositions.
What I know about the concept of transposition is it is defined if there are at least two distinct elements. But, in the above theorem, there's no assumption to prevent that n could be 1. I think, in that case, saying a product of transpositions is meaningless.
So, I think an assumption such as n\geq2 must be added in the above theorem.
Am I wrong?? If so, could you explain why??

Homework Equations





The Attempt at a Solution


Hi gotjrgkr! :smile:

It's called an empty product.
See: http://en.wikipedia.org/wiki/Empty_product
 
So, do you mean the theorem also makes sense even when n=1?
Are you sure?? Where can you find this? I mean, do you have a book explaing about it?
 
It's just a matter of choosing a definition of "product" that ensures that we don't have to state special cases separately. It's just a convenience. The statement makes sense for n=1 if we want it to.
 
Thanks!
 

Similar threads

Replies
8
Views
5K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 2 ·
Replies
2
Views
5K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 4 ·
Replies
4
Views
5K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
4
Views
5K
  • · Replies 3 ·
Replies
3
Views
3K
Replies
5
Views
3K