Basic Symmetric Group Representation Question

In summary, the permutation representation of Sn in ℂ^n has two invariant subspaces: the subspace where every coordinate of the vector is the same, and the subspace where all coordinates sum to zero. These are the only two independent subspaces, as the irreducible representations of the symmetric group in n letters are well-understood and are parametrized by partitions of n. These two subspaces have dimensions 1 and n-1 and do not intersect.
  • #1
zer0skill
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If you consider the permutation representation of Sn in ℂ^n, i.e the transformation which takes a permutation into the operator which uses it to permute the coordinates of a vector, then of course the subspace such that every coordinate of the vector is the same is invariant under the representation. Also, the subspace in which all coordinates sum to zero is invariant. But are there any others that are independent of these ones?
 
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  • #2
The irreducible representations of the symmetric group in n letters are actually quite well understood and to find them all actually for a given vector space over C. They are even paramtrized by partitions of n. I couldn't give the answer explicitly very quickly, but just look for books on it keeping in mind the terms Specht module and Young diagram.
 
  • #3
No, there are no others: the two subspaces you mention are irreducible, have dimensions 1 and n-1 (resp.), and intersect in zero.
 

1. What is a basic symmetric group representation?

A basic symmetric group representation is a way of representing a symmetric group using matrices. This allows us to easily manipulate and analyze the group's elements and operations.

2. How is a basic symmetric group representation related to group theory?

Group theory is the branch of mathematics that studies groups and their properties. A basic symmetric group representation is a tool used in group theory to analyze and understand symmetric groups.

3. What are some common applications of basic symmetric group representations?

Basic symmetric group representations have many applications in fields such as physics, chemistry, and computer science. They are particularly useful in studying symmetry and symmetry breaking in physical systems.

4. How do you construct a basic symmetric group representation?

To construct a basic symmetric group representation, you first need to choose a basis for the group. Then, each element of the group can be represented by a square matrix with entries corresponding to the basis elements. The group operations are then represented by matrix multiplication.

5. Can basic symmetric group representations be generalized to other types of groups?

Yes, basic symmetric group representations can be generalized to other types of groups, such as non-symmetric groups and Lie groups. However, the construction and properties of these representations may differ from those of basic symmetric group representations.

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