91Ó°ÊÓ

Explain why the set of all permutations of four elements is a permutation group. How many elements does this group have? This group is called the symmetric group on four letters and is denoted by \(S_{4}\).

In how many ways may we paint the faces of a cube with six different colors, using all six?

Is it true that the inverse of a bijection is a bijection?