# Linear representation theory of symmetric group:S5

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This article discusses the linear representation theory of the symmetric group of degree four. See also linear representation theory of symmetric groups for a general discussion of the linear representation theory of all symmetric groups of finite degree.

All representations of the symmetric group of degree four can be realized over the field of rational numbers, and can in fact be realized with integer entries.

## Family contexts

Family name | Parameter values | General discussion of linear representation theory of family |
---|---|---|

symmetric group | 4 | linear representation theory of symmetric groups |

projective general linear group of degree two | field:F5 | linear representation theory of projective general linear groups of degree two |

## Degrees of irreducible representations

FACTS TO CHECK AGAINST FOR DEGREES OF IRREDUCIBLE REPRESENTATIONS OVER SPLITTING FIELD:Divisibility facts: degree of irreducible representation divides group order | degree of irreducible representation divides index of abelian normal subgroupSize bounds: order of inner automorphism group bounds square of degree of irreducible representation| degree of irreducible representation is bounded by index of abelian subgroup| maximum degree of irreducible representation of group is less than or equal to product of maximum degree of irreducible representation of subgroup and index of subgroupCumulative facts: sum of squares of degrees of irreducible representations equals order of group | number of irreducible representations equals number of conjugacy classes | number of one-dimensional representations equals order of abelianization

Note that the linear representation theory of the symmetric group of degree four works over any field of characteristic not equal to two or three, and the list of degrees is .

### Explanation of degrees from the perspective of symmetric group of degree five

Common name of representation | Degree | Partition corresponding to representation | Hook length formula for degree | Conjugate partition | Representation for conjugate partition |
---|---|---|---|---|---|

trivial representation | 1 | 5 | 1 + 1 + 1 + 1 + 1 | sign representation | |

sign representation | 1 | 1 + 1 + 1 + 1 + 1 | 5 | trivial representation | |

standard representation | 4 | 4 + 1 (or is it 2 + 1 + 1 + 1?) | 2 + 1 + 1 + 1 (or is it 4 + 1?) | product of standard and sign representation | |

product of standard and sign representation | 4 | 2 + 1 + 1 + 1 (or is it 4 + 1?) | 4 + 1 (or is it 2 + 1 + 1 + 1?) | standard representation | |

irreducible five-dimensional representation | 5 | 3 + 2 | 2 + 2 + 1 | other irreducible five-dimensional representation | |

irreducible five-dimensional representation | 5 | 2 + 2 + 1 | 3 + 2 | other irreducible five-dimensional representation | |

exterior square of standard representation | 6 | 3 + 1 + 1 | 3 + 1 + 1 | the same representation, because the partition is self-conjugate. |