pub fn derived_length(degree: usize, gens: &[Perm]) -> Option<usize>Expand description
The derived length (solvability class): the number of steps the derived series G ⊵ G' ⊵ G'' ⊵ …
takes to reach the trivial group, or None if it never does (G is unsolvable). 0 is the trivial
group, 1 a non-trivial abelian group, 2 for S₃, 3 for S₄.