src/FOL/FOL.thy

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/FOL/FOL.thy	Thu Sep 16 12:20:38 1993 +0200
@@ -0,0 +1,4 @@
+FOL = IFOL +
+rules
+classical "(~P ==> P) ==> P"
+end