+elim (eqb n m).
+apply ((H H2)).
+apply ((H1 H2)).
+qed.
+
+theorem eqb_n_n: \forall n. eqb n n = true.
+intro.elim n.simplify.reflexivity.
+simplify.assumption.
+qed.
+
+theorem eqb_true_to_eq: \forall n,m:nat.
+eqb n m = true \to n = m.
+intros.
+change with
+match true with
+[ true \Rightarrow n = m
+| false \Rightarrow n \neq m].
+rewrite < H.
+apply eqb_to_Prop.
+qed.
+
+theorem eqb_false_to_not_eq: \forall n,m:nat.
+eqb n m = false \to n \neq m.
+intros.
+change with
+match false with
+[ true \Rightarrow n = m
+| false \Rightarrow n \neq m].
+rewrite < H.
+apply eqb_to_Prop.
+qed.
+
+theorem eq_to_eqb_true: \forall n,m:nat.
+n = m \to eqb n m = true.
+intros.apply (eqb_elim n m).
+intros. reflexivity.
+intros.apply False_ind.apply (H1 H).
+qed.
+
+theorem not_eq_to_eqb_false: \forall n,m:nat.
+\lnot (n = m) \to eqb n m = false.
+intros.apply (eqb_elim n m).
+intros. apply False_ind.apply (H H1).
+intros.reflexivity.