proposition: Lemma Sort_Inf_In : forall l p q, Sort l -> Inf q l -> InA eqk p l -> ltk q p.
proof: Proof. exact (SortA_InfA_InA eqk_equiv ltk_strorder ltk_compatk). Qed.
imports: SetoidList Bool OrderedType OrdersLists RelationPairs Orders RelationClasses