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diff --git a/matita/matita/lib/inconsistent.ma b/matita/matita/lib/inconsistent.ma
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+(**************************************************************************)
+(*       ___                                                              *)
+(*      ||M||                                                             *)
+(*      ||A||       A project by Andrea Asperti                           *)
+(*      ||T||                                                             *)
+(*      ||I||       Developers:                                           *)
+(*      ||T||         The HELM team.                                      *)
+(*      ||A||         http://helm.cs.unibo.it                             *)
+(*      \   /                                                             *)
+(*       \ /        This file is distributed under the terms of the       *)
+(*        v         GNU General Public License Version 2                  *)
+(*                                                                        *)
+(**************************************************************************)
+
+include "basics/logic.ma".
+
+axiom boh: (False → False) = True.
+
+definition J: False → False ≝ λf. match f in False with [ ].
+
+definition I2: True ≝ match boh with [ refl ⇒ J ].
+
+let rec err (u: True): False ≝ match u with [ I ⇒ err I2 ].
+
+lemma oops: False ≝ err I.