+(**************************************************************************)
+(* ___ *)
+(* ||M|| *)
+(* ||A|| A project by Andrea Asperti *)
+(* ||T|| *)
+(* ||I|| Developers: *)
+(* ||T|| A.Asperti, C.Sacerdoti Coen, *)
+(* ||A|| E.Tassi, S.Zacchiroli *)
+(* \ / *)
+(* \ / This file is distributed under the terms of the *)
+(* v GNU Lesser General Public License Version 2.1 *)
+(* *)
+(**************************************************************************)
+
(* Esercizio 0
===========
apply rule (⇒_i [h1] (∃x.¬ P x));
apply rule (RAA [h2] (⊥));
apply rule (¬_e (¬(∀x.P x)) (∀x.P x));
- [ apply rule (discharge [h1]);
+ [ apply rule (discharge [h2]);
| apply rule (∀_i {y} (P y));
apply rule (RAA [h3] (⊥));
apply rule (¬_e (¬∃x.¬ P x) (∃x.¬ P x));