Parameter MD2                : forall A a, A ε Kl a ≡≡ (A ε A ∧
(¬forall B, ¬(B ε a)) ∧
(forall B, (B ε a ⊃ B ε el A)) ∧
(forall B, B ε el A ⊃ ¬forall C D, ¬((C ε a) ∧ (D ε el C) ∧ (D ε el B)))).

Axiom klass_uniqueness       : forall A B a, (A ε Kl a ∧ B ε Kl a) ⊃ singular_equality A B.