X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fmatita%2Flibrary%2Flogic%2Fcprop_connectives.ma;h=c0bbdda18f3212715b49e5c8412cb7523c81e2ce;hb=5755ebe4016316a474ad8ab8d33b1a1a9187cc9e;hp=b4c556d83aca9bd2cef911156612ce8f837da713;hpb=80ea6f314e89d9d280338c41860cb04949319629;p=helm.git

diff --git a/helm/software/matita/library/logic/cprop_connectives.ma b/helm/software/matita/library/logic/cprop_connectives.ma
index b4c556d83..c0bbdda18 100644
--- a/helm/software/matita/library/logic/cprop_connectives.ma
+++ b/helm/software/matita/library/logic/cprop_connectives.ma
@@ -12,8 +12,7 @@
 (*                                                                        *)
 (**************************************************************************)
 
-include "logic/equality.ma".
-include "datatypes/constructors.ma".
+include "logic/connectives.ma".
 
 inductive Or (A,B:CProp) : CProp ≝
  | Left : A → Or A B
@@ -59,6 +58,13 @@ notation < "hvbox(a break ∧ b break ∧ c break ∧ d)" with precedence 35 for
  
 interpretation "constructive quaternary and" 'and4 x y z t = (And4 x y z t).
 
+record Iff (A,B:CProp) : CProp ≝
+ { if: A → B;
+   fi: B → A
+ }.
+
+interpretation "logical iff" 'iff x y = (Iff x y).
+
 inductive exT (A:Type) (P:A→CProp) : CProp ≝
   ex_introT: ∀w:A. P w → exT A P.