Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.In mathematics, the symmetric group on a set is the group consisting of all automorphisms of the set with function composition as the group operation. The symmetric group is important to diverse areas of mathematics such as Galois theory, invariant theory, the representation theory of Lie groups, and combinatorics. Cayley''s theorem states that every group G is isomorphic to a subgroup of the symmetric group on G.