diff -r d9096849bd8e -r 385d51d74f71 ex/PL.thy
--- a/ex/PL.thy	Tue Mar 22 08:26:25 1994 +0100
+++ b/ex/PL.thy	Tue Mar 22 08:28:31 1994 +0100
@@ -1,24 +1,18 @@
-(*  Title: 	HOL/ex/prop-log
+(*  Title: 	HOL/ex/pl.thy
     ID:         $Id$
     Author: 	Tobias Nipkow
-    Copyright   1991  University of Cambridge
+    Copyright   1994  TU Muenchen
 
 Inductive definition of propositional logic.
-
 *)
 
-PL = Finite +
-types pl 1
-arities pl :: (term)term
+PL = Finite + PL0 +
 consts
-    false	:: "'a pl"
-    "->"	:: "['a pl,'a pl] => 'a pl"	(infixr 90)
-    var		:: "'a => 'a pl"		("#_")
-    pl_rec	:: "['a pl,'a => 'b, 'b, ['b,'b] => 'b] => 'b"
     axK,axS,axDN:: "'a pl set"
     ruleMP,thms :: "'a pl set => 'a pl set"
     "|-" 	:: "['a pl set, 'a pl] => bool"	(infixl 50)
     "|="	:: "['a pl set, 'a pl] => bool"	(infixl 50)
+    pl_rec	:: "['a pl,'a => 'b, 'b, ['b,'b] => 'b] => 'b"
     eval	:: "['a set, 'a pl] => bool"	("_[_]" [100,0] 100)
     hyps	:: "['a pl, 'a set] => 'a pl set"
 rules
@@ -39,17 +33,13 @@
 
     sat_def "H |= p  ==  (!tt. (!q:H. tt[q]) --> tt[p])"
 
-pl_rec_var   "pl_rec(#v,f,y,z)    = f(v)"
-pl_rec_false "pl_rec(false,f,y,z) = y"
-pl_rec_imp   "pl_rec(p->q,f,y,g)  = g(pl_rec(p,f,y,g),pl_rec(q,f,y,g))"
-
-eval_def "tt[p] == pl_rec(p, %v.v:tt, False, op -->)"
+    pl_rec_var   "pl_rec(#v,f,y,z)    = f(v)"
+    pl_rec_false "pl_rec(false,f,y,z) = y"
+    pl_rec_imp   "pl_rec(p->q,f,y,g)  = g(pl_rec(p,f,y,g),pl_rec(q,f,y,g))"
 
-hyps_def
- "hyps(p,tt) == pl_rec(p, %a. {if(a:tt, #a, (#a)->false)}, {}, op Un)"
+    eval_def "tt[p] == pl_rec(p, %v.v:tt, False, op -->)"
 
-var_inject "(#v = #w) ==> v = w"
-imp_inject "[| (p -> q) = (p' -> q'); [| p = p'; q = q' |] ==> R |] ==> R"
-var_neq_imp "(#v = (p -> q)) ==> R"
-pl_ind "[| P(false); !!v. P(#v); !!p q. P(p)-->P(q)-->P(p->q)|] ==> !t.P(t)"
+    hyps_def
+      "hyps(p,tt) == pl_rec(p, %a. {if(a:tt, #a, (#a)->false)}, {}, op Un)"
+
 end