∀ n, O = (n - n)

Theorem minus_n_n : forall (n:nat), logic.eq (nat) O (minus n n).

theorem minus_n_n : \forall (n:nat). (eq) (nat) (O) ((minus) n n).

theorem minus_n_n : forall (n:nat.nat) , (((logic.eq_) (nat.nat)) ((nat.O) )) ((((nat.minus) ) (n)) (n)).

minus_n_n : LEMMA (FORALL(n:nat_sttfa.sttfa_nat):logic_sttfa_th.eq[nat_sttfa.sttfa_nat](nat_sttfa.sttfa_O)(nat_sttfa.minus(n)(n)))

Printing for OpenTheory is not working at the moment.