removed dead code, which has never been active in recorded history;

--- a/src/FOLP/IsaMakefile	Fri Dec 02 13:51:36 2011 +0100
+++ b/src/FOLP/IsaMakefile	Fri Dec 02 13:59:25 2011 +0100
@@ -36,9 +36,8 @@
 
 $(LOG)/FOLP-ex.gz: $(OUT)/FOLP ex/ROOT.ML ex/Foundation.thy ex/If.thy	\
   ex/Intro.thy ex/Nat.thy ex/Intuitionistic.thy ex/Classical.thy	\
-  ex/Prolog.ML ex/Prolog.thy ex/Propositional_Int.thy			\
-  ex/Propositional_Cla.thy ex/Quantifiers_Int.thy			\
-  ex/Quantifiers_Cla.thy
+  ex/Propositional_Int.thy ex/Propositional_Cla.thy			\
+  ex/Quantifiers_Int.thy ex/Quantifiers_Cla.thy
 	@$(ISABELLE_TOOL) usedir $(OUT)/FOLP ex
 
 

--- a/src/FOLP/ex/Prolog.ML	Fri Dec 02 13:51:36 2011 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,73 +0,0 @@
-(*  Title:      FOLP/ex/Prolog.ML
-    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
-    Copyright   1992  University of Cambridge
-
-For ex/prolog.thy.  First-Order Logic: PROLOG examples
-*)
-
-open Prolog;
-
-Goal "app(a:b:c:Nil, d:e:Nil, ?x)";
-by (resolve_tac [appNil,appCons] 1);
-by (resolve_tac [appNil,appCons] 1);
-by (resolve_tac [appNil,appCons] 1);
-by (resolve_tac [appNil,appCons] 1);
-result();
-
-Goal "app(?x, c:d:Nil, a:b:c:d:Nil)";
-by (REPEAT (resolve_tac [appNil,appCons] 1));
-result();
-
-
-Goal "app(?x, ?y, a:b:c:d:Nil)";
-by (REPEAT (resolve_tac [appNil,appCons] 1));
-back();
-back();
-back();
-back();
-result();
-
-
-(*app([x1,...,xn], y, ?z) requires (n+1) inferences*)
-(*rev([x1,...,xn], ?y) requires (n+1)(n+2)/2 inferences*)
-
-Goal "rev(a:b:c:d:Nil, ?x)";
-val rules = [appNil,appCons,revNil,revCons];
-by (REPEAT (resolve_tac rules 1));
-result();
-
-Goal "rev(a:b:c:d:e:f:g:h:i:j:k:l:m:n:Nil, ?w)";
-by (REPEAT (resolve_tac rules 1));
-result();
-
-Goal "rev(?x, a:b:c:Nil)";
-by (REPEAT (resolve_tac rules 1)); (*does not solve it directly!*)
-back();
-back();
-
-(*backtracking version*)
-val prolog_tac = DEPTH_FIRST (has_fewer_prems 1) (resolve_tac rules 1);
-
-choplev 0;
-by prolog_tac;
-result();
-
-Goal "rev(a:?x:c:?y:Nil, d:?z:b:?u)";
-by prolog_tac;
-result();
-
-(*rev([a..p], ?w) requires 153 inferences *)
-Goal "rev(a:b:c:d:e:f:g:h:i:j:k:l:m:n:o:p:Nil, ?w)";
-by (DEPTH_SOLVE (resolve_tac ([refl,conjI]@rules) 1));
-(*Poly/ML: 4 secs >> 38 lips*)
-result();
-
-(*?x has 16, ?y has 32;  rev(?y,?w) requires 561 (rather large) inferences;
-  total inferences = 2 + 1 + 17 + 561 = 581*)
-Goal
-    "a:b:c:d:e:f:g:h:i:j:k:l:m:n:o:p:Nil = ?x & app(?x,?x,?y) & rev(?y,?w)";
-by (DEPTH_SOLVE (resolve_tac ([refl,conjI]@rules) 1));
-(*Poly/ML: 29 secs >> 20 lips*)
-result();
-
-writeln"Reached end of file.";

--- a/src/FOLP/ex/Prolog.thy	Fri Dec 02 13:51:36 2011 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,21 +0,0 @@
-(*  Title:      FOLP/ex/Prolog.thy
-    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
-    Copyright   1992  University of Cambridge
-
-First-Order Logic: PROLOG examples
-
-Inherits from FOL the class term, the type o, and the coercion Trueprop
-*)
-
-Prolog = FOL +
-types   'a list
-arities list    :: (term)term
-consts  Nil     :: "'a list"
-        ":"     :: "['a, 'a list]=> 'a list"            (infixr 60)
-        app     :: "['a list, 'a list, 'a list] => o"
-        rev     :: "['a list, 'a list] => o"
-rules   appNil  "app(Nil,ys,ys)"
-        appCons "app(xs,ys,zs) ==> app(x:xs, ys, x:zs)"
-        revNil  "rev(Nil,Nil)"
-        revCons "[| rev(xs,ys);  app(ys, x:Nil, zs) |] ==> rev(x:xs, zs)"
-end