X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fmatita%2Flibrary%2Fdidactic%2Fexercises%2Fnatural_deduction_theories.ma;h=82e3b83fddabff7145544acec8333a8c77c42bf9;hb=4dc47c9675ffd5fa50296ffaa9b5997501518c98;hp=d955bd1248441bd0b762e14e198baada68ea71ed;hpb=ffdd3ddd6ce10a5fa0729ab407647bd46c44b9d8;p=helm.git

diff --git a/helm/software/matita/library/didactic/exercises/natural_deduction_theories.ma b/helm/software/matita/library/didactic/exercises/natural_deduction_theories.ma
index d955bd124..82e3b83fd 100644
--- a/helm/software/matita/library/didactic/exercises/natural_deduction_theories.ma
+++ b/helm/software/matita/library/didactic/exercises/natural_deduction_theories.ma
@@ -1,3 +1,17 @@
+(**************************************************************************)
+(*       ___	                                                          *)
+(*      ||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
    ===========