intros. auto.
qed.
-(* teorema di prova che non compila per via del let *)
-theorem le_gen_S_x_2: \forall m,x. (le (S m) x) \to let k \def (S O) in
- (\exists n. x = (S n) \land (le m n) \land k = k).
+theorem le_gen_S_x_2: \forall m,x. (le (S m) x) \to
+ \exists n. x = (S n) \land (le m n).
intros.
lapply le_gen_S_x to H using H0. elim H0. elim H1.
exists. exact x1. auto.
intros.
lapply le_gen_S_x_2 to H using H0. elim H0. elim H1.
lapply eq_gen_S_S to H2 using H4. rewrite left H4. assumption.
-qed.
\ No newline at end of file
+qed.