diff --git a/src/Pure/General/table.ML b/src/Pure/General/table.ML
--- a/src/Pure/General/table.ML
+++ b/src/Pure/General/table.ML
@@ -1,472 +1,484 @@
 (*  Title:      Pure/General/table.ML
     Author:     Markus Wenzel and Stefan Berghofer, TU Muenchen
 
 Generic tables.  Efficient purely functional implementation using
 balanced 2-3 trees.
 *)
 
 signature KEY =
 sig
   type key
   val ord: key ord
 end;
 
 signature TABLE =
 sig
   type key
   type 'a table
   exception DUP of key
   exception SAME
   exception UNDEF of key
   val empty: 'a table
   val build: ('a table -> 'a table) -> 'a table
   val is_empty: 'a table -> bool
   val is_single: 'a table -> bool
   val map: (key -> 'a -> 'b) -> 'a table -> 'b table
   val fold: (key * 'b -> 'a -> 'a) -> 'b table -> 'a -> 'a
   val fold_rev: (key * 'b -> 'a -> 'a) -> 'b table -> 'a -> 'a
   val dest: 'a table -> (key * 'a) list
   val keys: 'a table -> key list
   val min: 'a table -> (key * 'a) option
   val max: 'a table -> (key * 'a) option
   val exists: (key * 'a -> bool) -> 'a table -> bool
   val forall: (key * 'a -> bool) -> 'a table -> bool
   val get_first: (key * 'a -> 'b option) -> 'a table -> 'b option
   val lookup_key: 'a table -> key -> (key * 'a) option
   val lookup: 'a table -> key -> 'a option
   val defined: 'a table -> key -> bool
   val update: key * 'a -> 'a table -> 'a table
   val update_new: key * 'a -> 'a table -> 'a table                     (*exception DUP*)
   val default: key * 'a -> 'a table -> 'a table
   val map_entry: key -> ('a -> 'a) (*exception SAME*) -> 'a table -> 'a table
   val map_default: key * 'a -> ('a -> 'a) -> 'a table -> 'a table
   val make: (key * 'a) list -> 'a table                                (*exception DUP*)
   val join: (key -> 'a * 'a -> 'a) (*exception SAME*) ->
     'a table * 'a table -> 'a table                                    (*exception DUP*)
   val merge: ('a * 'a -> bool) -> 'a table * 'a table -> 'a table      (*exception DUP*)
   val delete: key -> 'a table -> 'a table                              (*exception UNDEF*)
   val delete_safe: key -> 'a table -> 'a table
   val member: ('b * 'a -> bool) -> 'a table -> key * 'b -> bool
   val insert: ('a * 'a -> bool) -> key * 'a -> 'a table -> 'a table    (*exception DUP*)
   val remove: ('b * 'a -> bool) -> key * 'b -> 'a table -> 'a table
   val lookup_list: 'a list table -> key -> 'a list
   val cons_list: key * 'a -> 'a list table -> 'a list table
   val insert_list: ('a * 'a -> bool) -> key * 'a -> 'a list table -> 'a list table
   val remove_list: ('b * 'a -> bool) -> key * 'b -> 'a list table -> 'a list table
   val update_list: ('a * 'a -> bool) -> key * 'a -> 'a list table -> 'a list table
   val make_list: (key * 'a) list -> 'a list table
   val dest_list: 'a list table -> (key * 'a) list
   val merge_list: ('a * 'a -> bool) -> 'a list table * 'a list table -> 'a list table
   type set = unit table
   val insert_set: key -> set -> set
   val remove_set: key -> set -> set
   val make_set: key list -> set
 end;
 
 functor Table(Key: KEY): TABLE =
 struct
 
 
 (* datatype table *)
 
 type key = Key.key;
 
 datatype 'a table =
   Empty |
   Branch2 of 'a table * (key * 'a) * 'a table |
   Branch3 of 'a table * (key * 'a) * 'a table * (key * 'a) * 'a table;
 
 exception DUP of key;
 
 
 (* empty and single *)
 
 val empty = Empty;
 
 fun build (f: 'a table -> 'a table) = f empty;
 
 fun is_empty Empty = true
   | is_empty _ = false;
 
 fun is_single (Branch2 (Empty, _, Empty)) = true
   | is_single _ = false;
 
 
 (* map and fold combinators *)
 
 fun map_table f =
   let
     fun map Empty = Empty
       | map (Branch2 (left, (k, x), right)) =
           Branch2 (map left, (k, f k x), map right)
       | map (Branch3 (left, (k1, x1), mid, (k2, x2), right)) =
           Branch3 (map left, (k1, f k1 x1), map mid, (k2, f k2 x2), map right);
   in map end;
 
 fun fold_table f =
   let
     fun fold Empty x = x
       | fold (Branch2 (left, p, right)) x =
           fold right (f p (fold left x))
       | fold (Branch3 (left, p1, mid, p2, right)) x =
           fold right (f p2 (fold mid (f p1 (fold left x))));
   in fold end;
 
 fun fold_rev_table f =
   let
     fun fold Empty x = x
       | fold (Branch2 (left, p, right)) x =
           fold left (f p (fold right x))
       | fold (Branch3 (left, p1, mid, p2, right)) x =
           fold left (f p1 (fold mid (f p2 (fold right x))));
   in fold end;
 
 fun dest tab = fold_rev_table cons tab [];
 fun keys tab = fold_rev_table (cons o #1) tab [];
 
 
 (* min/max entries *)
 
 fun min Empty = NONE
   | min (Branch2 (Empty, p, _)) = SOME p
   | min (Branch3 (Empty, p, _, _, _)) = SOME p
   | min (Branch2 (left, _, _)) = min left
   | min (Branch3 (left, _, _, _, _)) = min left;
 
 fun max Empty = NONE
   | max (Branch2 (_, p, Empty)) = SOME p
   | max (Branch3 (_, _, _, p, Empty)) = SOME p
   | max (Branch2 (_, _, right)) = max right
   | max (Branch3 (_, _, _, _, right)) = max right;
 
 
 (* exists and forall *)
 
 fun exists pred =
   let
     fun ex Empty = false
       | ex (Branch2 (left, (k, x), right)) =
           ex left orelse pred (k, x) orelse ex right
       | ex (Branch3 (left, (k1, x1), mid, (k2, x2), right)) =
           ex left orelse pred (k1, x1) orelse ex mid orelse pred (k2, x2) orelse ex right;
   in ex end;
 
 fun forall pred = not o exists (not o pred);
 
 
 (* get_first *)
 
 fun get_first f =
   let
     fun get Empty = NONE
       | get (Branch2 (left, (k, x), right)) =
           (case get left of
             NONE =>
               (case f (k, x) of
                 NONE => get right
               | some => some)
           | some => some)
       | get (Branch3 (left, (k1, x1), mid, (k2, x2), right)) =
           (case get left of
             NONE =>
               (case f (k1, x1) of
                 NONE =>
                   (case get mid of
                     NONE =>
                       (case f (k2, x2) of
                         NONE => get right
                       | some => some)
                   | some => some)
               | some => some)
           | some => some);
   in get end;
 
 
 (* lookup *)
 
 fun lookup tab key =
   let
     fun look Empty = NONE
       | look (Branch2 (left, (k, x), right)) =
           (case Key.ord (key, k) of
             LESS => look left
           | EQUAL => SOME x
           | GREATER => look right)
       | look (Branch3 (left, (k1, x1), mid, (k2, x2), right)) =
           (case Key.ord (key, k1) of
             LESS => look left
           | EQUAL => SOME x1
           | GREATER =>
               (case Key.ord (key, k2) of
                 LESS => look mid
               | EQUAL => SOME x2
               | GREATER => look right));
   in look tab end;
 
 fun lookup_key tab key =
   let
     fun look Empty = NONE
       | look (Branch2 (left, (k, x), right)) =
           (case Key.ord (key, k) of
             LESS => look left
           | EQUAL => SOME (k, x)
           | GREATER => look right)
       | look (Branch3 (left, (k1, x1), mid, (k2, x2), right)) =
           (case Key.ord (key, k1) of
             LESS => look left
           | EQUAL => SOME (k1, x1)
           | GREATER =>
               (case Key.ord (key, k2) of
                 LESS => look mid
               | EQUAL => SOME (k2, x2)
               | GREATER => look right));
   in look tab end;
 
 fun defined tab key =
   let
     fun def Empty = false
       | def (Branch2 (left, (k, x), right)) =
           (case Key.ord (key, k) of
             LESS => def left
           | EQUAL => true
           | GREATER => def right)
       | def (Branch3 (left, (k1, x1), mid, (k2, x2), right)) =
           (case Key.ord (key, k1) of
             LESS => def left
           | EQUAL => true
           | GREATER =>
               (case Key.ord (key, k2) of
                 LESS => def mid
               | EQUAL => true
               | GREATER => def right));
   in def tab end;
 
 
 (* modify *)
 
 datatype 'a growth =
   Stay of 'a table |
   Sprout of 'a table * (key * 'a) * 'a table;
 
 exception SAME;
 
 fun modify key f tab =
   let
     fun modfy Empty = Sprout (Empty, (key, f NONE), Empty)
       | modfy (Branch2 (left, p as (k, x), right)) =
           (case Key.ord (key, k) of
             LESS =>
               (case modfy left of
                 Stay left' => Stay (Branch2 (left', p, right))
               | Sprout (left1, q, left2) => Stay (Branch3 (left1, q, left2, p, right)))
           | EQUAL => Stay (Branch2 (left, (k, f (SOME x)), right))
           | GREATER =>
               (case modfy right of
                 Stay right' => Stay (Branch2 (left, p, right'))
               | Sprout (right1, q, right2) =>
                   Stay (Branch3 (left, p, right1, q, right2))))
       | modfy (Branch3 (left, p1 as (k1, x1), mid, p2 as (k2, x2), right)) =
           (case Key.ord (key, k1) of
             LESS =>
               (case modfy left of
                 Stay left' => Stay (Branch3 (left', p1, mid, p2, right))
               | Sprout (left1, q, left2) =>
                   Sprout (Branch2 (left1, q, left2), p1, Branch2 (mid, p2, right)))
           | EQUAL => Stay (Branch3 (left, (k1, f (SOME x1)), mid, p2, right))
           | GREATER =>
               (case Key.ord (key, k2) of
                 LESS =>
                   (case modfy mid of
                     Stay mid' => Stay (Branch3 (left, p1, mid', p2, right))
                   | Sprout (mid1, q, mid2) =>
                       Sprout (Branch2 (left, p1, mid1), q, Branch2 (mid2, p2, right)))
               | EQUAL => Stay (Branch3 (left, p1, mid, (k2, f (SOME x2)), right))
               | GREATER =>
                   (case modfy right of
                     Stay right' => Stay (Branch3 (left, p1, mid, p2, right'))
                   | Sprout (right1, q, right2) =>
                       Sprout (Branch2 (left, p1, mid), p2, Branch2 (right1, q, right2)))));
 
   in
     (case modfy tab of
       Stay tab' => tab'
     | Sprout br => Branch2 br)
     handle SAME => tab
   end;
 
 fun update (key, x) tab = modify key (fn _ => x) tab;
 fun update_new (key, x) tab = modify key (fn NONE => x | SOME _ => raise DUP key) tab;
 fun default (key, x) tab = modify key (fn NONE => x | SOME _ => raise SAME) tab;
 fun map_entry key f = modify key (fn NONE => raise SAME | SOME x => f x);
 fun map_default (key, x) f = modify key (fn NONE => f x | SOME y => f y);
 
 
 (* delete *)
 
 exception UNDEF of key;
 
 local
 
 fun compare NONE (k2, _) = LESS
   | compare (SOME k1) (k2, _) = Key.ord (k1, k2);
 
 fun if_eq EQUAL x y = x
   | if_eq _ x y = y;
 
 fun del (SOME k) Empty = raise UNDEF k
   | del NONE (Branch2 (Empty, p, Empty)) = (p, (true, Empty))
   | del NONE (Branch3 (Empty, p, Empty, q, Empty)) =
       (p, (false, Branch2 (Empty, q, Empty)))
-  | del k (Branch2 (Empty, p, Empty)) = (case compare k p of
-      EQUAL => (p, (true, Empty)) | _ => raise UNDEF (the k))
-  | del k (Branch3 (Empty, p, Empty, q, Empty)) = (case compare k p of
-      EQUAL => (p, (false, Branch2 (Empty, q, Empty)))
-    | _ => (case compare k q of
-        EQUAL => (q, (false, Branch2 (Empty, p, Empty)))
-      | _ => raise UNDEF (the k)))
-  | del k (Branch2 (l, p, r)) = (case compare k p of
-      LESS => (case del k l of
-        (p', (false, l')) => (p', (false, Branch2 (l', p, r)))
-      | (p', (true, l')) => (p', case r of
-          Branch2 (rl, rp, rr) =>
-            (true, Branch3 (l', p, rl, rp, rr))
-        | Branch3 (rl, rp, rm, rq, rr) => (false, Branch2
-            (Branch2 (l', p, rl), rp, Branch2 (rm, rq, rr)))))
-    | ord => (case del (if_eq ord NONE k) r of
-        (p', (false, r')) => (p', (false, Branch2 (l, if_eq ord p' p, r')))
-      | (p', (true, r')) => (p', case l of
-          Branch2 (ll, lp, lr) =>
-            (true, Branch3 (ll, lp, lr, if_eq ord p' p, r'))
-        | Branch3 (ll, lp, lm, lq, lr) => (false, Branch2
-            (Branch2 (ll, lp, lm), lq, Branch2 (lr, if_eq ord p' p, r'))))))
-  | del k (Branch3 (l, p, m, q, r)) = (case compare k q of
-      LESS => (case compare k p of
-        LESS => (case del k l of
-          (p', (false, l')) => (p', (false, Branch3 (l', p, m, q, r)))
-        | (p', (true, l')) => (p', (false, case (m, r) of
-            (Branch2 (ml, mp, mr), Branch2 _) =>
-              Branch2 (Branch3 (l', p, ml, mp, mr), q, r)
-          | (Branch3 (ml, mp, mm, mq, mr), _) =>
-              Branch3 (Branch2 (l', p, ml), mp, Branch2 (mm, mq, mr), q, r)
-          | (Branch2 (ml, mp, mr), Branch3 (rl, rp, rm, rq, rr)) =>
-              Branch3 (Branch2 (l', p, ml), mp, Branch2 (mr, q, rl), rp,
-                Branch2 (rm, rq, rr)))))
-      | ord => (case del (if_eq ord NONE k) m of
-          (p', (false, m')) =>
-            (p', (false, Branch3 (l, if_eq ord p' p, m', q, r)))
-        | (p', (true, m')) => (p', (false, case (l, r) of
-            (Branch2 (ll, lp, lr), Branch2 _) =>
-              Branch2 (Branch3 (ll, lp, lr, if_eq ord p' p, m'), q, r)
-          | (Branch3 (ll, lp, lm, lq, lr), _) =>
-              Branch3 (Branch2 (ll, lp, lm), lq,
-                Branch2 (lr, if_eq ord p' p, m'), q, r)
-          | (_, Branch3 (rl, rp, rm, rq, rr)) =>
-              Branch3 (l, if_eq ord p' p, Branch2 (m', q, rl), rp,
-                Branch2 (rm, rq, rr))))))
-    | ord => (case del (if_eq ord NONE k) r of
-        (q', (false, r')) =>
-          (q', (false, Branch3 (l, p, m, if_eq ord q' q, r')))
-      | (q', (true, r')) => (q', (false, case (l, m) of
-          (Branch2 _, Branch2 (ml, mp, mr)) =>
-            Branch2 (l, p, Branch3 (ml, mp, mr, if_eq ord q' q, r'))
-        | (_, Branch3 (ml, mp, mm, mq, mr)) =>
-            Branch3 (l, p, Branch2 (ml, mp, mm), mq,
-              Branch2 (mr, if_eq ord q' q, r'))
-        | (Branch3 (ll, lp, lm, lq, lr), Branch2 (ml, mp, mr)) =>
-            Branch3 (Branch2 (ll, lp, lm), lq, Branch2 (lr, p, ml), mp,
-              Branch2 (mr, if_eq ord q' q, r'))))));
+  | del k (Branch2 (Empty, p, Empty)) =
+      (case compare k p of
+        EQUAL => (p, (true, Empty))
+      | _ => raise UNDEF (the k))
+  | del k (Branch3 (Empty, p, Empty, q, Empty)) =
+      (case compare k p of
+        EQUAL => (p, (false, Branch2 (Empty, q, Empty)))
+      | _ =>
+        (case compare k q of
+          EQUAL => (q, (false, Branch2 (Empty, p, Empty)))
+        | _ => raise UNDEF (the k)))
+  | del k (Branch2 (l, p, r)) =
+      (case compare k p of
+        LESS =>
+          (case del k l of
+            (p', (false, l')) => (p', (false, Branch2 (l', p, r)))
+          | (p', (true, l')) => (p', case r of
+              Branch2 (rl, rp, rr) =>
+                (true, Branch3 (l', p, rl, rp, rr))
+            | Branch3 (rl, rp, rm, rq, rr) => (false, Branch2
+                (Branch2 (l', p, rl), rp, Branch2 (rm, rq, rr)))))
+      | ord =>
+          (case del (if_eq ord NONE k) r of
+            (p', (false, r')) => (p', (false, Branch2 (l, if_eq ord p' p, r')))
+          | (p', (true, r')) => (p', case l of
+              Branch2 (ll, lp, lr) =>
+                (true, Branch3 (ll, lp, lr, if_eq ord p' p, r'))
+            | Branch3 (ll, lp, lm, lq, lr) => (false, Branch2
+                (Branch2 (ll, lp, lm), lq, Branch2 (lr, if_eq ord p' p, r'))))))
+  | del k (Branch3 (l, p, m, q, r)) =
+      (case compare k q of
+        LESS =>
+          (case compare k p of
+            LESS =>
+              (case del k l of
+                (p', (false, l')) => (p', (false, Branch3 (l', p, m, q, r)))
+              | (p', (true, l')) => (p', (false, case (m, r) of
+                  (Branch2 (ml, mp, mr), Branch2 _) =>
+                    Branch2 (Branch3 (l', p, ml, mp, mr), q, r)
+                | (Branch3 (ml, mp, mm, mq, mr), _) =>
+                    Branch3 (Branch2 (l', p, ml), mp, Branch2 (mm, mq, mr), q, r)
+                | (Branch2 (ml, mp, mr), Branch3 (rl, rp, rm, rq, rr)) =>
+                    Branch3 (Branch2 (l', p, ml), mp, Branch2 (mr, q, rl), rp,
+                      Branch2 (rm, rq, rr)))))
+          | ord =>
+              (case del (if_eq ord NONE k) m of
+                (p', (false, m')) =>
+                  (p', (false, Branch3 (l, if_eq ord p' p, m', q, r)))
+              | (p', (true, m')) => (p', (false, case (l, r) of
+                  (Branch2 (ll, lp, lr), Branch2 _) =>
+                    Branch2 (Branch3 (ll, lp, lr, if_eq ord p' p, m'), q, r)
+                | (Branch3 (ll, lp, lm, lq, lr), _) =>
+                    Branch3 (Branch2 (ll, lp, lm), lq,
+                      Branch2 (lr, if_eq ord p' p, m'), q, r)
+                | (_, Branch3 (rl, rp, rm, rq, rr)) =>
+                    Branch3 (l, if_eq ord p' p, Branch2 (m', q, rl), rp,
+                      Branch2 (rm, rq, rr))))))
+      | ord =>
+          (case del (if_eq ord NONE k) r of
+            (q', (false, r')) =>
+              (q', (false, Branch3 (l, p, m, if_eq ord q' q, r')))
+          | (q', (true, r')) => (q', (false, case (l, m) of
+              (Branch2 _, Branch2 (ml, mp, mr)) =>
+                Branch2 (l, p, Branch3 (ml, mp, mr, if_eq ord q' q, r'))
+            | (_, Branch3 (ml, mp, mm, mq, mr)) =>
+                Branch3 (l, p, Branch2 (ml, mp, mm), mq,
+                  Branch2 (mr, if_eq ord q' q, r'))
+            | (Branch3 (ll, lp, lm, lq, lr), Branch2 (ml, mp, mr)) =>
+                Branch3 (Branch2 (ll, lp, lm), lq, Branch2 (lr, p, ml), mp,
+                  Branch2 (mr, if_eq ord q' q, r'))))));
 
 in
 
 fun delete key tab = snd (snd (del (SOME key) tab));
 fun delete_safe key tab = if defined tab key then delete key tab else tab;
 
 end;
 
 
 (* membership operations *)
 
 fun member eq tab (key, x) =
   (case lookup tab key of
     NONE => false
   | SOME y => eq (x, y));
 
 fun insert eq (key, x) =
   modify key (fn NONE => x | SOME y => if eq (x, y) then raise SAME else raise DUP key);
 
 fun remove eq (key, x) tab =
   (case lookup tab key of
     NONE => tab
   | SOME y => if eq (x, y) then delete key tab else tab);
 
 
 (* simultaneous modifications *)
 
 fun make entries = build (fold update_new entries);
 
 fun join f (table1, table2) =
   let
     fun add (key, y) tab = modify key (fn NONE => y | SOME x => f key (x, y)) tab;
   in
     if pointer_eq (table1, table2) then table1
     else if is_empty table1 then table2
     else fold_table add table2 table1
   end;
 
 fun merge eq = join (fn key => fn xy => if eq xy then raise SAME else raise DUP key);
 
 
 (* list tables *)
 
 fun lookup_list tab key = these (lookup tab key);
 
 fun cons_list (key, x) tab = modify key (fn NONE => [x] | SOME xs => x :: xs) tab;
 
 fun insert_list eq (key, x) =
   modify key (fn NONE => [x] | SOME xs => if Library.member eq xs x then raise SAME else x :: xs);
 
 fun remove_list eq (key, x) tab =
   map_entry key (fn xs => (case Library.remove eq x xs of [] => raise UNDEF key | ys => ys)) tab
   handle UNDEF _ => delete key tab;
 
 fun update_list eq (key, x) =
   modify key (fn NONE => [x] | SOME [] => [x] | SOME (xs as y :: _) =>
     if eq (x, y) then raise SAME else Library.update eq x xs);
 
 fun make_list args = build (fold_rev cons_list args);
 fun dest_list tab = maps (fn (key, xs) => map (pair key) xs) (dest tab);
 fun merge_list eq = join (fn _ => Library.merge eq);
 
 
 (* set operations *)
 
 type set = unit table;
 
 fun insert_set x = default (x, ());
 fun remove_set x : set -> set = delete_safe x;
 fun make_set xs = build (fold insert_set xs);
 
 
 (* ML pretty-printing *)
 
 val _ =
   ML_system_pp (fn depth => fn pretty => fn tab =>
     ML_Pretty.to_polyml
       (ML_Pretty.enum "," "{" "}"
         (ML_Pretty.pair
           (ML_Pretty.from_polyml o ML_system_pretty)
           (ML_Pretty.from_polyml o pretty))
         (dest tab, depth)));
 
 
 (*final declarations of this structure!*)
 val map = map_table;
 val fold = fold_table;
 val fold_rev = fold_rev_table;
 
 end;
 
 structure Inttab = Table(type key = int val ord = int_ord);
 structure Symtab = Table(type key = string val ord = fast_string_ord);
 structure Symreltab = Table(type key = string * string
   val ord = prod_ord fast_string_ord fast_string_ord);