Implicit Types (A B C : {set gT}) (G H K L M : {group gT}).Local Notation groupT := (group_of (Phant gT)).Definition simple A := minnormal A A.Notation "r .-series" := (path (rel_of_simpl_rel (group_rel_of r)))
  (at level 2, format "r .-series") : group_scope.Notation "G .-chief" := (chief_factor G)
  (at level 2, format "G .-chief") : group_rel_scope.Implicit Types G H U V : {group gT}.Implicit Types gT rT : finGroupType.

Lemma chief_factor_minnormal G V U : chief_factor G V U -> minnormal (U / V) (G / V).