diff --git a/src/Pure/more_thm.ML b/src/Pure/more_thm.ML
--- a/src/Pure/more_thm.ML
+++ b/src/Pure/more_thm.ML
@@ -1,786 +1,786 @@
 (*  Title:      Pure/more_thm.ML
     Author:     Makarius
 
 Further operations on type ctyp/cterm/thm, outside the inference kernel.
 *)
 
 infix aconvc;
 
 signature BASIC_THM =
 sig
   include BASIC_THM
   val show_consts: bool Config.T
   val show_hyps: bool Config.T
   val show_tags: bool Config.T
   structure Ctermtab: TABLE
   structure Thmtab: TABLE
   val aconvc: cterm * cterm -> bool
   type attribute = Context.generic * thm -> Context.generic option * thm option
 end;
 
 signature THM =
 sig
   include THM
   structure Ctermtab: TABLE
   structure Thmtab: TABLE
   val eq_ctyp: ctyp * ctyp -> bool
   val aconvc: cterm * cterm -> bool
   val add_tvars: thm -> ctyp Term_Subst.TVars.table -> ctyp Term_Subst.TVars.table
   val add_vars: thm -> cterm Term_Subst.Vars.table -> cterm Term_Subst.Vars.table
   val frees_of: thm -> cterm list
   val dest_funT: ctyp -> ctyp * ctyp
   val strip_type: ctyp -> ctyp list * ctyp
   val all_name: Proof.context -> string * cterm -> cterm -> cterm
   val all: Proof.context -> cterm -> cterm -> cterm
   val mk_binop: cterm -> cterm -> cterm -> cterm
   val dest_binop: cterm -> cterm * cterm
   val dest_implies: cterm -> cterm * cterm
   val dest_equals: cterm -> cterm * cterm
   val dest_equals_lhs: cterm -> cterm
   val dest_equals_rhs: cterm -> cterm
   val lhs_of: thm -> cterm
   val rhs_of: thm -> cterm
   val fast_term_ord: cterm ord
   val term_ord: cterm ord
   val thm_ord: thm ord
   val cterm_cache: (cterm -> 'a) -> cterm -> 'a
   val thm_cache: (thm -> 'a) -> thm -> 'a
   val is_reflexive: thm -> bool
   val eq_thm: thm * thm -> bool
   val eq_thm_prop: thm * thm -> bool
   val eq_thm_strict: thm * thm -> bool
   val equiv_thm: theory -> thm * thm -> bool
   val class_triv: theory -> class -> thm
   val of_sort: ctyp * sort -> thm list
   val is_dummy: thm -> bool
   val add_thm: thm -> thm list -> thm list
   val del_thm: thm -> thm list -> thm list
   val merge_thms: thm list * thm list -> thm list
   val item_net: thm Item_Net.T
   val item_net_intro: thm Item_Net.T
   val item_net_elim: thm Item_Net.T
   val declare_hyps: cterm -> Proof.context -> Proof.context
   val assume_hyps: cterm -> Proof.context -> thm * Proof.context
   val unchecked_hyps: Proof.context -> Proof.context
   val restore_hyps: Proof.context -> Proof.context -> Proof.context
   val undeclared_hyps: Context.generic -> thm -> term list
   val check_hyps: Context.generic -> thm -> thm
   val declare_term_sorts: term -> Proof.context -> Proof.context
   val extra_shyps': Proof.context -> thm -> sort list
   val check_shyps: Proof.context -> thm -> thm
   val weaken_sorts': Proof.context -> cterm -> cterm
   val elim_implies: thm -> thm -> thm
   val forall_intr_name: string * cterm -> thm -> thm
   val forall_elim_var: int -> thm -> thm
   val forall_elim_vars: int -> thm -> thm
   val instantiate_frees: ((string * sort) * ctyp) list * ((string * typ) * cterm) list -> thm -> thm
   val instantiate': ctyp option list -> cterm option list -> thm -> thm
   val forall_intr_frees: thm -> thm
   val forall_intr_vars: thm -> thm
   val unvarify_global: theory -> thm -> thm
   val unvarify_axiom: theory -> string -> thm
   val rename_params_rule: string list * int -> thm -> thm
   val rename_boundvars: term -> term -> thm -> thm
   val add_axiom: Proof.context -> binding * term -> theory -> (string * thm) * theory
   val add_axiom_global: binding * term -> theory -> (string * thm) * theory
   val add_def: Defs.context -> bool -> bool -> binding * term -> theory -> (string * thm) * theory
   val add_def_global: bool -> bool -> binding * term -> theory -> (string * thm) * theory
   type attribute = Context.generic * thm -> Context.generic option * thm option
   type binding = binding * attribute list
   val tag_rule: string * string -> thm -> thm
   val untag_rule: string -> thm -> thm
   val is_free_dummy: thm -> bool
   val tag_free_dummy: thm -> thm
   val def_name: string -> string
   val def_name_optional: string -> string -> string
   val def_binding: Binding.binding -> Binding.binding
   val def_binding_optional: Binding.binding -> Binding.binding -> Binding.binding
   val make_def_binding: bool -> Binding.binding -> Binding.binding
   val has_name_hint: thm -> bool
   val get_name_hint: thm -> string
   val put_name_hint: string -> thm -> thm
   val theoremK: string
   val legacy_get_kind: thm -> string
   val kind_rule: string -> thm -> thm
   val rule_attribute: thm list -> (Context.generic -> thm -> thm) -> attribute
   val declaration_attribute: (thm -> Context.generic -> Context.generic) -> attribute
   val mixed_attribute: (Context.generic * thm -> Context.generic * thm) -> attribute
   val apply_attribute: attribute -> thm -> Context.generic -> thm * Context.generic
   val attribute_declaration: attribute -> thm -> Context.generic -> Context.generic
   val theory_attributes: attribute list -> thm -> theory -> thm * theory
   val proof_attributes: attribute list -> thm -> Proof.context -> thm * Proof.context
   val no_attributes: 'a -> 'a * 'b list
   val simple_fact: 'a -> ('a * 'b list) list
   val tag: string * string -> attribute
   val untag: string -> attribute
   val kind: string -> attribute
   val register_proofs: thm list lazy -> theory -> theory
   val consolidate_theory: theory -> unit
   val expose_theory: theory -> unit
   val show_consts: bool Config.T
   val show_hyps: bool Config.T
   val show_tags: bool Config.T
   val pretty_thm_raw: Proof.context -> {quote: bool, show_hyps: bool} -> thm -> Pretty.T
   val pretty_thm: Proof.context -> thm -> Pretty.T
   val pretty_thm_item: Proof.context -> thm -> Pretty.T
   val pretty_thm_global: theory -> thm -> Pretty.T
   val string_of_thm: Proof.context -> thm -> string
   val string_of_thm_global: theory -> thm -> string
 end;
 
 structure Thm: THM =
 struct
 
 (** basic operations **)
 
 (* collecting ctyps and cterms *)
 
 val eq_ctyp = op = o apply2 Thm.typ_of;
 val op aconvc = op aconv o apply2 Thm.term_of;
 
 val add_tvars =
   Thm.fold_atomic_ctyps {hyps = false} Term.is_TVar (fn cT => fn tab =>
     let val v = Term.dest_TVar (Thm.typ_of cT)
     in tab |> not (Term_Subst.TVars.defined tab v) ? Term_Subst.TVars.update (v, cT) end);
 
 val add_vars =
   Thm.fold_atomic_cterms {hyps = false} Term.is_Var (fn ct => fn tab =>
     let val v = Term.dest_Var (Thm.term_of ct)
     in tab |> not (Term_Subst.Vars.defined tab v) ? Term_Subst.Vars.update (v, ct) end);
 
 fun frees_of th =
   (th, (Term_Subst.Frees.empty, [])) |-> Thm.fold_atomic_cterms {hyps = true} Term.is_Free
     (fn ct => fn (set, list) =>
       let val v = Term.dest_Free (Thm.term_of ct) in
         if not (Term_Subst.Frees.defined set v)
         then (Term_Subst.Frees.add (v, ()) set, ct :: list)
         else (set, list)
       end)
   |> #2;
 
 
 (* ctyp operations *)
 
 fun dest_funT cT =
   (case Thm.typ_of cT of
     Type ("fun", _) => let val [A, B] = Thm.dest_ctyp cT in (A, B) end
   | T => raise TYPE ("dest_funT", [T], []));
 
 (* ctyp version of strip_type: maps  [T1,...,Tn]--->T  to   ([T1,T2,...,Tn], T) *)
 fun strip_type cT =
   (case Thm.typ_of cT of
     Type ("fun", _) =>
       let
         val (cT1, cT2) = dest_funT cT;
         val (cTs, cT') = strip_type cT2
       in (cT1 :: cTs, cT') end
   | _ => ([], cT));
 
 
 (* cterm operations *)
 
 fun all_name ctxt (x, t) A =
   let
     val T = Thm.typ_of_cterm t;
     val all_const = Thm.cterm_of ctxt (Const ("Pure.all", (T --> propT) --> propT));
   in Thm.apply all_const (Thm.lambda_name (x, t) A) end;
 
 fun all ctxt t A = all_name ctxt ("", t) A;
 
 fun mk_binop c a b = Thm.apply (Thm.apply c a) b;
 fun dest_binop ct = (Thm.dest_arg1 ct, Thm.dest_arg ct);
 
 fun dest_implies ct =
   (case Thm.term_of ct of
     Const ("Pure.imp", _) $ _ $ _ => dest_binop ct
   | _ => raise TERM ("dest_implies", [Thm.term_of ct]));
 
 fun dest_equals ct =
   (case Thm.term_of ct of
     Const ("Pure.eq", _) $ _ $ _ => dest_binop ct
   | _ => raise TERM ("dest_equals", [Thm.term_of ct]));
 
 fun dest_equals_lhs ct =
   (case Thm.term_of ct of
     Const ("Pure.eq", _) $ _ $ _ => Thm.dest_arg1 ct
   | _ => raise TERM ("dest_equals_lhs", [Thm.term_of ct]));
 
 fun dest_equals_rhs ct =
   (case Thm.term_of ct of
     Const ("Pure.eq", _) $ _ $ _ => Thm.dest_arg ct
   | _ => raise TERM ("dest_equals_rhs", [Thm.term_of ct]));
 
 val lhs_of = dest_equals_lhs o Thm.cprop_of;
 val rhs_of = dest_equals_rhs o Thm.cprop_of;
 
 
 (* certified term order *)
 
 val fast_term_ord = Term_Ord.fast_term_ord o apply2 Thm.term_of;
 val term_ord = Term_Ord.term_ord o apply2 Thm.term_of;
 
 
 (* thm order: ignores theory context! *)
 
 val thm_ord =
   Term_Ord.fast_term_ord o apply2 Thm.prop_of
   ||| list_ord (prod_ord Term_Ord.fast_term_ord Term_Ord.fast_term_ord) o apply2 Thm.tpairs_of
   ||| list_ord Term_Ord.fast_term_ord o apply2 Thm.hyps_of
   ||| list_ord Term_Ord.sort_ord o apply2 Thm.shyps_of;
 
 
 (* tables and caches *)
 
 structure Ctermtab = Table(type key = cterm val ord = fast_term_ord);
 structure Thmtab = Table(type key = thm val ord = thm_ord);
 
 fun cterm_cache f = Cache.create Ctermtab.empty Ctermtab.lookup Ctermtab.update f;
 fun thm_cache f = Cache.create Thmtab.empty Thmtab.lookup Thmtab.update f;
 
 
 (* equality *)
 
 fun is_reflexive th = op aconv (Logic.dest_equals (Thm.prop_of th))
   handle TERM _ => false;
 
 val eq_thm = is_equal o thm_ord;
 
 val eq_thm_prop = op aconv o apply2 Thm.full_prop_of;
 
 fun eq_thm_strict ths =
   eq_thm ths andalso
   Context.eq_thy_id (apply2 Thm.theory_id ths) andalso
   op = (apply2 Thm.maxidx_of ths) andalso
   op = (apply2 Thm.get_tags ths);
 
 
 (* pattern equivalence *)
 
 fun equiv_thm thy ths =
   Pattern.equiv thy (apply2 (Thm.full_prop_of o Thm.transfer thy) ths);
 
 
 (* type classes and sorts *)
 
 fun class_triv thy c =
   Thm.of_class (Thm.global_ctyp_of thy (TVar ((Name.aT, 0), [c])), c);
 
 fun of_sort (T, S) = map (fn c => Thm.of_class (T, c)) S;
 
 
 (* misc operations *)
 
 fun is_dummy thm =
   (case try Logic.dest_term (Thm.concl_of thm) of
     NONE => false
   | SOME t => Term.is_dummy_pattern (Term.head_of t));
 
 
 (* collections of theorems in canonical order *)
 
 val add_thm = update eq_thm_prop;
 val del_thm = remove eq_thm_prop;
 val merge_thms = merge eq_thm_prop;
 
 val item_net = Item_Net.init eq_thm_prop (single o Thm.full_prop_of);
 val item_net_intro = Item_Net.init eq_thm_prop (single o Thm.concl_of);
 val item_net_elim = Item_Net.init eq_thm_prop (single o Thm.major_prem_of);
 
 
 
 (** declared hyps and sort hyps **)
 
 structure Hyps = Proof_Data
 (
   type T = {checked_hyps: bool, hyps: Termtab.set, shyps: sort Ord_List.T};
   fun init _ : T = {checked_hyps = true, hyps = Termtab.empty, shyps = []};
 );
 
 fun map_hyps f = Hyps.map (fn {checked_hyps, hyps, shyps} =>
   let val (checked_hyps', hyps', shyps') = f (checked_hyps, hyps, shyps)
   in {checked_hyps = checked_hyps', hyps = hyps', shyps = shyps'} end);
 
 
 (* hyps *)
 
 fun declare_hyps raw_ct ctxt = ctxt |> map_hyps (fn (checked_hyps, hyps, shyps) =>
   let
     val ct = Thm.transfer_cterm (Proof_Context.theory_of ctxt) raw_ct;
     val hyps' = Termtab.update (Thm.term_of ct, ()) hyps;
   in (checked_hyps, hyps', shyps) end);
 
 fun assume_hyps ct ctxt = (Thm.assume ct, declare_hyps ct ctxt);
 
 val unchecked_hyps = map_hyps (fn (_, hyps, shyps) => (false, hyps, shyps));
 
 fun restore_hyps ctxt =
   map_hyps (fn (_, hyps, shyps) => (#checked_hyps (Hyps.get ctxt), hyps, shyps));
 
 fun undeclared_hyps context th =
   Thm.hyps_of th
   |> filter_out
     (case context of
       Context.Theory _ => K false
     | Context.Proof ctxt =>
         (case Hyps.get ctxt of
           {checked_hyps = false, ...} => K true
         | {hyps, ...} => Termtab.defined hyps));
 
 fun check_hyps context th =
   (case undeclared_hyps context th of
     [] => th
   | undeclared =>
       error (Pretty.string_of (Pretty.big_list "Undeclared hyps:"
         (map (Pretty.item o single o Syntax.pretty_term (Syntax.init_pretty context)) undeclared))));
 
 
 (* shyps *)
 
 fun declare_term_sorts t =
   map_hyps (fn (checked_hyps, hyps, shyps) =>
     (checked_hyps, hyps, Sorts.insert_term t shyps));
 
 fun extra_shyps' ctxt th =
   Sorts.subtract (#shyps (Hyps.get ctxt)) (Thm.extra_shyps th);
 
 fun check_shyps ctxt raw_th =
   let
     val th = Thm.strip_shyps raw_th;
     val extra_shyps = extra_shyps' ctxt th;
   in
     if null extra_shyps then th
     else error (Pretty.string_of (Pretty.block (Pretty.str "Pending sort hypotheses:" ::
       Pretty.brk 1 :: Pretty.commas (map (Syntax.pretty_sort ctxt) extra_shyps))))
   end;
 
 val weaken_sorts' = Thm.weaken_sorts o #shyps o Hyps.get;
 
 
 
 (** basic derived rules **)
 
 (*Elimination of implication
   A    A \<Longrightarrow> B
   ------------
         B
 *)
 fun elim_implies thA thAB = Thm.implies_elim thAB thA;
 
 
 (* forall_intr_name *)
 
 fun forall_intr_name (a, x) th =
   let
     val th' = Thm.forall_intr x th;
     val prop' = (case Thm.prop_of th' of all $ Abs (_, T, b) => all $ Abs (a, T, b));
   in Thm.renamed_prop prop' th' end;
 
 
 (* forall_elim_var(s) *)
 
 local
 
 fun dest_all ct =
   (case Thm.term_of ct of
     Const ("Pure.all", _) $ Abs (a, _, _) =>
       let val (x, ct') = Thm.dest_abs NONE (Thm.dest_arg ct)
       in SOME ((a, Thm.ctyp_of_cterm x), ct') end
   | _ => NONE);
 
 fun dest_all_list ct =
   (case dest_all ct of
     NONE => []
   | SOME (v, ct') => v :: dest_all_list ct');
 
 fun forall_elim_vars_list vars i th =
   let
     val used =
       (Thm.fold_terms {hyps = false} o Term.fold_aterms)
         (fn Var ((x, j), _) => if i = j then insert (op =) x else I | _ => I) th [];
     val vars' = (Name.variant_list used (map #1 vars), vars)
       |> ListPair.map (fn (x, (_, T)) => Thm.var ((x, i), T));
   in fold Thm.forall_elim vars' th end;
 
 in
 
 fun forall_elim_vars i th =
   forall_elim_vars_list (dest_all_list (Thm.cprop_of th)) i th;
 
 fun forall_elim_var i th =
   let
     val vars =
       (case dest_all (Thm.cprop_of th) of
         SOME (v, _) => [v]
       | NONE => raise THM ("forall_elim_var", i, [th]));
   in forall_elim_vars_list vars i th end;
 
 end;
 
 
 (* instantiate frees *)
 
 fun instantiate_frees ([], []) th = th
   | instantiate_frees (instT, inst) th =
       let
         val idx = Thm.maxidx_of th + 1;
         fun index ((a, A), b) = (((a, idx), A), b);
         val insts = (map index instT, map index inst);
         val tfrees = Symtab.build (fold (Symtab.insert_set o #1 o #1) instT);
         val frees = Symtab.build (fold (Symtab.insert_set o #1 o #1) inst);
 
         val hyps = Thm.chyps_of th;
         val inst_cterm =
           Thm.generalize_cterm (tfrees, frees) idx #>
           Thm.instantiate_cterm insts;
       in
         th
         |> fold_rev Thm.implies_intr hyps
         |> Thm.generalize (tfrees, frees) idx
         |> Thm.instantiate insts
         |> fold (elim_implies o Thm.assume o inst_cterm) hyps
       end;
 
 
 (* instantiate by left-to-right occurrence of variables *)
 
 fun instantiate' cTs cts thm =
   let
     fun err msg =
       raise TYPE ("instantiate': " ^ msg,
         map_filter (Option.map Thm.typ_of) cTs,
         map_filter (Option.map Thm.term_of) cts);
 
     fun zip_vars xs ys =
       zip_options xs ys handle ListPair.UnequalLengths =>
         err "more instantiations than variables in thm";
 
     val instT = zip_vars (build_rev (Thm.fold_terms {hyps = false} Term.add_tvars thm)) cTs;
     val thm' = Thm.instantiate (instT, []) thm;
     val inst = zip_vars (build_rev (Thm.fold_terms {hyps = false} Term.add_vars thm')) cts;
   in Thm.instantiate ([], inst) thm' end;
 
 
 (* implicit generalization over variables -- canonical order *)
 
 fun forall_intr_vars th =
   let val vs = build (th |> Thm.fold_atomic_cterms {hyps = false} Term.is_Var (insert (op aconvc)))
   in fold Thm.forall_intr vs th end;
 
 fun forall_intr_frees th =
   let
-    val fixed0 =
+    val fixed =
       Term_Subst.Frees.build
        (fold Term_Subst.add_frees (Thm.terms_of_tpairs (Thm.tpairs_of th)) #>
         fold Term_Subst.add_frees (Thm.hyps_of th));
     val (_, frees) =
-      (th, (fixed0, [])) |-> Thm.fold_atomic_cterms {hyps = false} Term.is_Free
-        (fn ct => fn (fixed, frees) =>
+      (th, (fixed, [])) |-> Thm.fold_atomic_cterms {hyps = false} Term.is_Free
+        (fn ct => fn (seen, frees) =>
           let val v = Term.dest_Free (Thm.term_of ct) in
-            if not (Term_Subst.Frees.defined fixed v)
-            then (Term_Subst.Frees.add (v, ()) fixed, ct :: frees)
-            else (fixed, frees)
+            if not (Term_Subst.Frees.defined seen v)
+            then (Term_Subst.Frees.add (v, ()) seen, ct :: frees)
+            else (seen, frees)
           end);
   in fold Thm.forall_intr frees th end;
 
 
 (* unvarify_global: global schematic variables *)
 
 fun unvarify_global thy th =
   let
     val prop = Thm.full_prop_of th;
     val _ = map Logic.unvarify_global (prop :: Thm.hyps_of th)
       handle TERM (msg, _) => raise THM (msg, 0, [th]);
 
     val cert = Thm.global_cterm_of thy;
     val certT = Thm.global_ctyp_of thy;
 
     val instT =
       Term_Subst.TVars.build (prop |> (Term.fold_types o Term.fold_atyps)
         (fn T => fn instT =>
           (case T of
             TVar (v as ((a, _), S)) =>
               if Term_Subst.TVars.defined instT v then instT
               else Term_Subst.TVars.update (v, TFree (a, S)) instT
           | _ => instT)));
     val cinstT = Term_Subst.TVars.map (K certT) instT;
     val cinst =
       Term_Subst.Vars.build (prop |> Term.fold_aterms
         (fn t => fn inst =>
           (case t of
             Var ((x, i), T) =>
               let val T' = Term_Subst.instantiateT instT T
               in Term_Subst.Vars.update (((x, i), T'), cert (Free ((x, T')))) inst end
           | _ => inst)));
   in Thm.instantiate (Term_Subst.TVars.dest cinstT, Term_Subst.Vars.dest cinst) th end;
 
 fun unvarify_axiom thy = unvarify_global thy o Thm.axiom thy;
 
 
 (* user renaming of parameters in a subgoal *)
 
 (*The names, if distinct, are used for the innermost parameters of subgoal i;
   preceding parameters may be renamed to make all parameters distinct.*)
 fun rename_params_rule (names, i) st =
   let
     val (_, Bs, Bi, C) = Thm.dest_state (st, i);
     val params = map #1 (Logic.strip_params Bi);
     val short = length params - length names;
     val names' =
       if short < 0 then error "More names than parameters in subgoal!"
       else Name.variant_list names (take short params) @ names;
     val free_names = Term.fold_aterms (fn Free (x, _) => insert (op =) x | _ => I) Bi [];
     val Bi' = Logic.list_rename_params names' Bi;
   in
     (case duplicates (op =) names of
       a :: _ => (warning ("Can't rename.  Bound variables not distinct: " ^ a); st)
     | [] =>
       (case inter (op =) names free_names of
         a :: _ => (warning ("Can't rename.  Bound/Free variable clash: " ^ a); st)
       | [] => Thm.renamed_prop (Logic.list_implies (Bs @ [Bi'], C)) st))
   end;
 
 
 (* preservation of bound variable names *)
 
 fun rename_boundvars pat obj th =
   (case Term.rename_abs pat obj (Thm.prop_of th) of
     NONE => th
   | SOME prop' => Thm.renamed_prop prop' th);
 
 
 
 (** specification primitives **)
 
 (* rules *)
 
 fun stripped_sorts thy t =
   let
     val tfrees = build_rev (Term.add_tfrees t);
     val tfrees' = map (fn a => (a, [])) (Name.variant_list [] (map #1 tfrees));
     val recover =
       map2 (fn (a', S') => fn (a, S) => (((a', 0), S'), Thm.global_ctyp_of thy (TVar ((a, 0), S))))
         tfrees' tfrees;
     val strip = map (apply2 TFree) (tfrees ~~ tfrees');
     val t' = Term.map_types (Term.map_atyps (perhaps (AList.lookup (op =) strip))) t;
   in (strip, recover, t') end;
 
 fun add_axiom ctxt (b, prop) thy =
   let
     val _ = Sign.no_vars ctxt prop;
     val (strip, recover, prop') = stripped_sorts thy prop;
     val constraints = map (fn (TFree (_, S), T) => (T, S)) strip;
     val of_sorts = maps (fn (T as TFree (_, S), _) => of_sort (Thm.ctyp_of ctxt T, S)) strip;
 
     val thy' = thy
       |> Theory.add_axiom ctxt (b, Logic.list_implies (maps Logic.mk_of_sort constraints, prop'));
     val axm_name = Sign.full_name thy' b;
     val axm' = Thm.axiom thy' axm_name;
     val thm =
       Thm.instantiate (recover, []) axm'
       |> unvarify_global thy'
       |> fold elim_implies of_sorts;
   in ((axm_name, thm), thy') end;
 
 fun add_axiom_global arg thy = add_axiom (Syntax.init_pretty_global thy) arg thy;
 
 fun add_def (context as (ctxt, _)) unchecked overloaded (b, prop) thy =
   let
     val _ = Sign.no_vars ctxt prop;
     val prems = map (Thm.cterm_of ctxt) (Logic.strip_imp_prems prop);
     val (_, recover, concl') = stripped_sorts thy (Logic.strip_imp_concl prop);
 
     val thy' = Theory.add_def context unchecked overloaded (b, concl') thy;
     val axm_name = Sign.full_name thy' b;
     val axm' = Thm.axiom thy' axm_name;
     val thm =
       Thm.instantiate (recover, []) axm'
       |> unvarify_global thy'
       |> fold_rev Thm.implies_intr prems;
   in ((axm_name, thm), thy') end;
 
 fun add_def_global unchecked overloaded arg thy =
   add_def (Defs.global_context thy) unchecked overloaded arg thy;
 
 
 
 (** theorem tags **)
 
 (* add / delete tags *)
 
 fun tag_rule tg = Thm.map_tags (insert (op =) tg);
 fun untag_rule s = Thm.map_tags (filter_out (fn (s', _) => s = s'));
 
 
 (* free dummy thm -- for abstract closure *)
 
 val free_dummyN = "free_dummy";
 fun is_free_dummy thm = Properties.defined (Thm.get_tags thm) free_dummyN;
 val tag_free_dummy = tag_rule (free_dummyN, "");
 
 
 (* def_name *)
 
 fun def_name c = c ^ "_def";
 
 fun def_name_optional c "" = def_name c
   | def_name_optional _ name = name;
 
 val def_binding = Binding.map_name def_name #> Binding.reset_pos;
 fun def_binding_optional b name = if Binding.is_empty name then def_binding b else name;
 fun make_def_binding cond b = if cond then def_binding b else Binding.empty;
 
 
 (* unofficial theorem names *)
 
 fun has_name_hint thm = AList.defined (op =) (Thm.get_tags thm) Markup.nameN;
 fun the_name_hint thm = the (AList.lookup (op =) (Thm.get_tags thm) Markup.nameN);
 fun get_name_hint thm = if has_name_hint thm then the_name_hint thm else "??.unknown";
 
 fun put_name_hint name = untag_rule Markup.nameN #> tag_rule (Markup.nameN, name);
 
 
 (* theorem kinds *)
 
 val theoremK = "theorem";
 
 fun legacy_get_kind thm = the_default "" (Properties.get (Thm.get_tags thm) Markup.kindN);
 
 fun kind_rule k = tag_rule (Markup.kindN, k) o untag_rule Markup.kindN;
 
 
 
 (** attributes **)
 
 (*attributes subsume any kind of rules or context modifiers*)
 type attribute = Context.generic * thm -> Context.generic option * thm option;
 
 type binding = binding * attribute list;
 
 fun rule_attribute ths f (x, th) =
   (NONE,
     (case find_first is_free_dummy (th :: ths) of
       SOME th' => SOME th'
     | NONE => SOME (f x th)));
 
 fun declaration_attribute f (x, th) =
   (if is_free_dummy th then NONE else SOME (f th x), NONE);
 
 fun mixed_attribute f (x, th) =
   let val (x', th') = f (x, th) in (SOME x', SOME th') end;
 
 fun apply_attribute (att: attribute) th x =
   let val (x', th') = att (x, check_hyps x (Thm.transfer'' x th))
   in (the_default th th', the_default x x') end;
 
 fun attribute_declaration att th x = #2 (apply_attribute att th x);
 
 fun apply_attributes mk dest =
   let
     fun app [] th x = (th, x)
       | app (att :: atts) th x = apply_attribute att th (mk x) ||> dest |-> app atts;
   in app end;
 
 val theory_attributes = apply_attributes Context.Theory Context.the_theory;
 val proof_attributes = apply_attributes Context.Proof Context.the_proof;
 
 fun no_attributes x = (x, []);
 fun simple_fact x = [(x, [])];
 
 fun tag tg = rule_attribute [] (K (tag_rule tg));
 fun untag s = rule_attribute [] (K (untag_rule s));
 fun kind k = rule_attribute [] (K (k <> "" ? kind_rule k));
 
 
 
 (** forked proofs **)
 
 structure Proofs = Theory_Data
 (
   type T = thm list lazy Inttab.table;
   val empty = Inttab.empty;
   val extend = I;
   val merge = Inttab.merge (K true);
 );
 
 fun reset_proofs thy =
   if Inttab.is_empty (Proofs.get thy) then NONE
   else SOME (Proofs.put Inttab.empty thy);
 
 val _ = Theory.setup (Theory.at_begin reset_proofs);
 
 fun register_proofs ths thy =
   let val entry = (serial (), Lazy.map_finished (map Thm.trim_context) ths)
   in (Proofs.map o Inttab.update) entry thy end;
 
 fun force_proofs thy =
   Proofs.get thy |> Inttab.dest |> maps (map (Thm.transfer thy) o Lazy.force o #2);
 
 val consolidate_theory = Thm.consolidate o force_proofs;
 
 fun expose_theory thy =
   if Proofterm.export_enabled ()
   then Thm.expose_proofs thy (force_proofs thy) else ();
 
 
 
 (** print theorems **)
 
 (* options *)
 
 val show_consts = Config.declare_option_bool ("show_consts", \<^here>);
 val show_hyps = Config.declare_bool ("show_hyps", \<^here>) (K false);
 val show_tags = Config.declare_bool ("show_tags", \<^here>) (K false);
 
 
 (* pretty_thm etc. *)
 
 fun pretty_tag (name, arg) = Pretty.strs [name, quote arg];
 val pretty_tags = Pretty.list "[" "]" o map pretty_tag;
 
 fun pretty_thm_raw ctxt {quote, show_hyps = show_hyps'} raw_th =
   let
     val show_tags = Config.get ctxt show_tags;
     val show_hyps = Config.get ctxt show_hyps;
 
     val th = raw_th
       |> perhaps (try (Thm.transfer' ctxt))
       |> perhaps (try Thm.strip_shyps);
 
     val hyps = if show_hyps then Thm.hyps_of th else undeclared_hyps (Context.Proof ctxt) th;
     val extra_shyps = extra_shyps' ctxt th;
     val tags = Thm.get_tags th;
     val tpairs = Thm.tpairs_of th;
 
     val q = if quote then Pretty.quote else I;
     val prt_term = q o Syntax.pretty_term ctxt;
 
 
     val hlen = length extra_shyps + length hyps + length tpairs;
     val hsymbs =
       if hlen = 0 then []
       else if show_hyps orelse show_hyps' then
         [Pretty.brk 2, Pretty.list "[" "]"
           (map (q o Syntax.pretty_flexpair ctxt) tpairs @ map prt_term hyps @
            map (Syntax.pretty_sort ctxt) extra_shyps)]
       else [Pretty.brk 2, Pretty.str ("[" ^ replicate_string hlen "." ^ "]")];
     val tsymbs =
       if null tags orelse not show_tags then []
       else [Pretty.brk 1, pretty_tags tags];
   in Pretty.block (prt_term (Thm.prop_of th) :: (hsymbs @ tsymbs)) end;
 
 fun pretty_thm ctxt = pretty_thm_raw ctxt {quote = false, show_hyps = true};
 fun pretty_thm_item ctxt th = Pretty.item [pretty_thm ctxt th];
 
 fun pretty_thm_global thy =
   pretty_thm_raw (Syntax.init_pretty_global thy) {quote = false, show_hyps = false};
 
 val string_of_thm = Pretty.string_of oo pretty_thm;
 val string_of_thm_global = Pretty.string_of oo pretty_thm_global;
 
 
 open Thm;
 
 end;
 
 structure Basic_Thm: BASIC_THM = Thm;
 open Basic_Thm;