Some lemmas moves to the file they belong to.

[helm.git] / matita / library / nat / relevant_equations.ma

diff --git a/matita/library/nat/relevant_equations.ma b/matita/library/nat/relevant_equations.ma
index 9e275aa9ca8a6e8828af7fab7c7073b502cd26b7..6e641708021d79d36c81b67283f889949e1fe43c 100644 (file)
--- a/matita/library/nat/relevant_equations.ma
+++ b/matita/library/nat/relevant_equations.ma
@@ -50,3 +50,13 @@ rewrite > distr_times_plus.
 rewrite > distr_times_plus.
 rewrite < assoc_plus.reflexivity.
 qed.
+
+theorem eq_pred_to_eq:
+ ∀n,m. O < n → O < m → pred n = pred m → n = m.
+intros;
+generalize in match (eq_f ? ? S ? ? H2);
+intro;
+rewrite < S_pred in H3;
+rewrite < S_pred in H3;
+assumption.
+qed.