simplify. intros.
discriminate H3.
qed.
+
+(* Piu' semplice e non lascia l'ipotesi inutile Hcut *)
+alias id "refl_equal" = "cic:/Coq/Init/Logic/eq.ind#xpointer(1/1/1)".
+theorem test_inversion2: \forall n. le n O \to n=O.
+ intros.
+ generalize (refl_equal nat O).
+ apply (le_ind ? (\lambda x. O=x \to n=x) ? ? ? H).
+ intro. reflexivity.
+ simplify. intros.
+ discriminate H3.
+qed.