End QuotientNil.
Section Solvable.
Variable gT : finGroupType.
Implicit Types G H : {group gT}.

(* Specifications: *)
Lemma nilpotent_sol G : nilpotent G -> solvable G.
Lemma abelian_sol G : abelian G -> solvable G.
Lemma sol_der1_proper G H :
solvable G -> H \subset G -> H :!=: 1 -> H^`(1) \proper H.
Lemma derivedP G : reflect (exists n, G^`(n) = 1) (solvable G).
End Solvable.