English
The collection of permutations of a fintype α forms a fintype.
Русский
Множество перестановок конечного типа α образует конечный тип.
LaTeX
$$$[Fintype \\alpha] \\Rightarrow Fintype (Perm(\\alpha)).$$$
Lean4
/-- The collection of permutations of a fintype is a fintype. -/
def fintypePerm [Fintype α] : Fintype (Perm α) :=
⟨permsOfFinset (@Finset.univ α _), by simp [mem_perms_of_finset_iff]⟩