X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Flib%2Fbasics%2Fsets.ma;h=43b22bff6900c1a329610a05596c4a37b41346a6;hb=bc477154d15f6979c948f9af602199af547d193e;hp=cdc6ac9e8e278e19c3d7957bf600f7150ae1d895;hpb=791b0dc201a023e772e4ba5c3da697c5ae271405;p=helm.git

diff --git a/matita/matita/lib/basics/sets.ma b/matita/matita/lib/basics/sets.ma
index cdc6ac9e8..43b22bff6 100644
--- a/matita/matita/lib/basics/sets.ma
+++ b/matita/matita/lib/basics/sets.ma
@@ -13,7 +13,7 @@ include "basics/logic.ma".
 
 (**** a subset of A is just an object of type A→Prop ****)
 
-definition empty_set ≝ λA:Type[0].λa:A.False.
+definition empty_set ≝ λA:Type[0].λa:A.⊥.
 notation "\emptyv" non associative with precedence 90 for @{'empty_set}.
 interpretation "empty set" 'empty_set = (empty_set ?).