X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fmatita%2Flibrary%2Flogic%2Fconnectives.ma;h=5afc3e5dc29d7db0f45e812d244f6cd72e4ff7f6;hb=f79585fe2f19c4a545938e189439d87b2611a47a;hp=bb08b8038bf51c37d533a0889c2493fd04fdc810;hpb=73284b016dc2c195491ab3442457ec9fb76b576f;p=helm.git

diff --git a/helm/software/matita/library/logic/connectives.ma b/helm/software/matita/library/logic/connectives.ma
index bb08b8038..5afc3e5dc 100644
--- a/helm/software/matita/library/logic/connectives.ma
+++ b/helm/software/matita/library/logic/connectives.ma
@@ -82,3 +82,5 @@ interpretation "exists" 'exists \eta.x =
 inductive ex2 (A:Type) (P,Q:A \to Prop) : Prop \def
     ex_intro2: \forall x:A. P x \to Q x \to ex2 A P Q.
 
+definition iff :=
+ \lambda A,B. (A -> B) \land (B -> A).
\ No newline at end of file