src/Pure/logic.ML
author wenzelm
Tue Jul 14 12:18:52 2009 +0200 (2009-07-14)
changeset 32004 6ef7056e5215
parent 31981 9c59cbb9c5a2
child 32008 fa0cc3c8f73d
permissions -rw-r--r--
removed obsolete/unused legacy_unvarify;
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(*  Title:      Pure/logic.ML
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    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
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    Author:     Makarius
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Abstract syntax operations of the Pure meta-logic.
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*)
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signature LOGIC =
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sig
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  val all: term -> term -> term
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  val is_all: term -> bool
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  val dest_all: term -> (string * typ) * term
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  val mk_equals: term * term -> term
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  val dest_equals: term -> term * term
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  val implies: term
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  val mk_implies: term * term -> term
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  val dest_implies: term -> term * term
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  val list_implies: term list * term -> term
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  val strip_imp_prems: term -> term list
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  val strip_imp_concl: term -> term
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  val strip_prems: int * term list * term -> term list * term
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  val count_prems: term -> int
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  val nth_prem: int * term -> term
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  val true_prop: term
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  val conjunction: term
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  val mk_conjunction: term * term -> term
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  val mk_conjunction_list: term list -> term
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  val mk_conjunction_balanced: term list -> term
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  val dest_conjunction: term -> term * term
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  val dest_conjunction_list: term -> term list
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  val dest_conjunction_balanced: int -> term -> term list
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  val dest_conjunctions: term -> term list
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  val strip_horn: term -> term list * term
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  val mk_type: typ -> term
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  val dest_type: term -> typ
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  val type_map: (term -> term) -> typ -> typ
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  val const_of_class: class -> string
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  val class_of_const: string -> class
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  val mk_of_class: typ * class -> term
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  val dest_of_class: term -> typ * class
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  val name_classrel: string * string -> string
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  val mk_classrel: class * class -> term
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  val dest_classrel: term -> class * class
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  val name_arities: arity -> string list
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  val name_arity: string * sort list * class -> string
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  val mk_arities: arity -> term list
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  val dest_arity: term -> string * sort list * class
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  val protectC: term
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  val protect: term -> term
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  val unprotect: term -> term
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  val mk_term: term -> term
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  val dest_term: term -> term
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  val occs: term * term -> bool
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  val close_form: term -> term
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  val combound: term * int * int -> term
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  val rlist_abs: (string * typ) list * term -> term
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  val incr_indexes: typ list * int -> term -> term
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  val incr_tvar: int -> typ -> typ
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  val lift_abs: int -> term -> term -> term
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  val lift_all: int -> term -> term -> term
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  val strip_assums_hyp: term -> term list
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  val strip_assums_concl: term -> term
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  val strip_params: term -> (string * typ) list
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  val has_meta_prems: term -> bool
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  val flatten_params: int -> term -> term
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  val list_rename_params: string list * term -> term
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  val assum_pairs: int * term -> (term*term)list
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  val assum_problems: int * term -> (term -> term) * term list * term
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  val varifyT: typ -> typ
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  val unvarifyT: typ -> typ
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  val varify: term -> term
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  val unvarify: term -> term
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  val legacy_varifyT: typ -> typ
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  val legacy_varify: term -> term
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  val get_goal: term -> int -> term
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  val goal_params: term -> int -> term * term list
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  val prems_of_goal: term -> int -> term list
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  val concl_of_goal: term -> int -> term
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end;
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structure Logic : LOGIC =
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struct
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(*** Abstract syntax operations on the meta-connectives ***)
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(** all **)
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fun all v t = Const ("all", (Term.fastype_of v --> propT) --> propT) $ lambda v t;
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fun is_all (Const ("all", _) $ Abs _) = true
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  | is_all _ = false;
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fun dest_all (Const ("all", _) $ Abs (abs as (_, T, _))) =
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      let val (x, b) = Term.dest_abs abs  (*potentially slow*)
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      in ((x, T), b) end
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  | dest_all t = raise TERM ("dest_all", [t]);
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(** equality **)
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fun mk_equals (t, u) =
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  let val T = Term.fastype_of t
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  in Const ("==", T --> T --> propT) $ t $ u end;
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fun dest_equals (Const ("==", _) $ t $ u) = (t, u)
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  | dest_equals t = raise TERM ("dest_equals", [t]);
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(** implies **)
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val implies = Const ("==>", propT --> propT --> propT);
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fun mk_implies (A, B) = implies $ A $ B;
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fun dest_implies (Const ("==>", _) $ A $ B) = (A, B)
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  | dest_implies A = raise TERM ("dest_implies", [A]);
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(** nested implications **)
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(* [A1,...,An], B  goes to  A1==>...An==>B  *)
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fun list_implies ([], B) = B
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  | list_implies (A::As, B) = implies $ A $ list_implies(As,B);
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(* A1==>...An==>B  goes to  [A1,...,An], where B is not an implication *)
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fun strip_imp_prems (Const("==>", _) $ A $ B) = A :: strip_imp_prems B
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  | strip_imp_prems _ = [];
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(* A1==>...An==>B  goes to B, where B is not an implication *)
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fun strip_imp_concl (Const("==>", _) $ A $ B) = strip_imp_concl B
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  | strip_imp_concl A = A : term;
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(*Strip and return premises: (i, [], A1==>...Ai==>B)
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    goes to   ([Ai, A(i-1),...,A1] , B)         (REVERSED)
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  if  i<0 or else i too big then raises  TERM*)
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fun strip_prems (0, As, B) = (As, B)
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  | strip_prems (i, As, Const("==>", _) $ A $ B) =
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        strip_prems (i-1, A::As, B)
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  | strip_prems (_, As, A) = raise TERM("strip_prems", A::As);
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(*Count premises -- quicker than (length o strip_prems) *)
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fun count_prems (Const ("==>", _) $ _ $ B) = 1 + count_prems B
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  | count_prems _ = 0;
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(*Select Ai from A1 ==>...Ai==>B*)
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fun nth_prem (1, Const ("==>", _) $ A $ _) = A
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  | nth_prem (i, Const ("==>", _) $ _ $ B) = nth_prem (i - 1, B)
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  | nth_prem (_, A) = raise TERM ("nth_prem", [A]);
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(*strip a proof state (Horn clause):
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  B1 ==> ... Bn ==> C   goes to   ([B1, ..., Bn], C)    *)
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fun strip_horn A = (strip_imp_prems A, strip_imp_concl A);
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(** conjunction **)
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val true_prop = Term.all propT $ Abs ("dummy", propT, mk_implies (Bound 0, Bound 0));
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val conjunction = Const ("Pure.conjunction", propT --> propT --> propT);
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(*A &&& B*)
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fun mk_conjunction (A, B) = conjunction $ A $ B;
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(*A &&& B &&& C -- improper*)
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fun mk_conjunction_list [] = true_prop
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  | mk_conjunction_list ts = foldr1 mk_conjunction ts;
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(*(A &&& B) &&& (C &&& D) -- balanced*)
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fun mk_conjunction_balanced [] = true_prop
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  | mk_conjunction_balanced ts = BalancedTree.make mk_conjunction ts;
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(*A &&& B*)
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fun dest_conjunction (Const ("Pure.conjunction", _) $ A $ B) = (A, B)
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  | dest_conjunction t = raise TERM ("dest_conjunction", [t]);
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(*A &&& B &&& C -- improper*)
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fun dest_conjunction_list t =
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  (case try dest_conjunction t of
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    NONE => [t]
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  | SOME (A, B) => A :: dest_conjunction_list B);
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(*(A &&& B) &&& (C &&& D) -- balanced*)
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fun dest_conjunction_balanced 0 _ = []
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  | dest_conjunction_balanced n t = BalancedTree.dest dest_conjunction n t;
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(*((A &&& B) &&& C) &&& D &&& E -- flat*)
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fun dest_conjunctions t =
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  (case try dest_conjunction t of
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    NONE => [t]
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  | SOME (A, B) => dest_conjunctions A @ dest_conjunctions B);
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(** types as terms **)
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fun mk_type ty = Const ("TYPE", Term.itselfT ty);
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fun dest_type (Const ("TYPE", Type ("itself", [ty]))) = ty
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  | dest_type t = raise TERM ("dest_type", [t]);
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fun type_map f = dest_type o f o mk_type;
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(** type classes **)
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(* const names *)
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val classN = "_class";
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val const_of_class = suffix classN;
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fun class_of_const c = unsuffix classN c
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  handle Fail _ => raise TERM ("class_of_const: bad name " ^ quote c, []);
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(* class membership *)
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fun mk_of_class (ty, c) =
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  Const (const_of_class c, Term.itselfT ty --> propT) $ mk_type ty;
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fun dest_of_class (t as Const (c_class, _) $ ty) = (dest_type ty, class_of_const c_class)
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  | dest_of_class t = raise TERM ("dest_of_class", [t]);
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(* class relations *)
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fun name_classrel (c1, c2) =
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  Long_Name.base_name c1 ^ "_" ^ Long_Name.base_name c2;
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fun mk_classrel (c1, c2) = mk_of_class (Term.aT [c1], c2);
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fun dest_classrel tm =
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  (case dest_of_class tm of
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    (TVar (_, [c1]), c2) => (c1, c2)
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  | _ => raise TERM ("dest_classrel", [tm]));
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(* type arities *)
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fun name_arities (t, _, S) =
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  let val b = Long_Name.base_name t
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  in S |> map (fn c => Long_Name.base_name c ^ "_" ^ b) end;
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fun name_arity (t, dom, c) = hd (name_arities (t, dom, [c]));
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fun mk_arities (t, Ss, S) =
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  let val T = Type (t, ListPair.map TFree (Name.invents Name.context Name.aT (length Ss), Ss))
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  in map (fn c => mk_of_class (T, c)) S end;
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fun dest_arity tm =
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  let
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    fun err () = raise TERM ("dest_arity", [tm]);
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    val (ty, c) = dest_of_class tm;
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    val (t, tvars) =
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      (case ty of
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        Type (t, tys) => (t, map dest_TVar tys handle TYPE _ => err ())
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      | _ => err ());
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    val Ss =
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      if has_duplicates (eq_fst (op =)) tvars then err ()
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      else map snd tvars;
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  in (t, Ss, c) end;
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(** protected propositions and embedded terms **)
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val protectC = Const ("prop", propT --> propT);
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fun protect t = protectC $ t;
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fun unprotect (Const ("prop", _) $ t) = t
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  | unprotect t = raise TERM ("unprotect", [t]);
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fun mk_term t = Const ("Pure.term", Term.fastype_of t --> propT) $ t;
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fun dest_term (Const ("Pure.term", _) $ t) = t
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  | dest_term t = raise TERM ("dest_term", [t]);
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(*** Low-level term operations ***)
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(*Does t occur in u?  Or is alpha-convertible to u?
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  The term t must contain no loose bound variables*)
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fun occs (t, u) = exists_subterm (fn s => t aconv s) u;
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(*Close up a formula over all free variables by quantification*)
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fun close_form A =
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  Term.list_all_free (rev (Term.add_frees A []), A);
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(*** Specialized operations for resolution... ***)
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(*computes t(Bound(n+k-1),...,Bound(n))  *)
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fun combound (t, n, k) =
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    if  k>0  then  combound (t,n+1,k-1) $ (Bound n)  else  t;
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(* ([xn,...,x1], t)   ======>   (x1,...,xn)t *)
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fun rlist_abs ([], body) = body
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  | rlist_abs ((a,T)::pairs, body) = rlist_abs(pairs, Abs(a, T, body));
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local exception SAME in
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fun incrT k =
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  let
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    fun incr (TVar ((a, i), S)) = TVar ((a, i + k), S)
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      | incr (Type (a, Ts)) = Type (a, incrs Ts)
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      | incr _ = raise SAME
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    and incrs (T :: Ts) =
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        (incr T :: (incrs Ts handle SAME => Ts)
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          handle SAME => T :: incrs Ts)
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      | incrs [] = raise SAME;
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  in incr end;
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(*For all variables in the term, increment indexnames and lift over the Us
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    result is ?Gidx(B.(lev+n-1),...,B.lev) where lev is abstraction level *)
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fun incr_indexes ([], 0) t = t
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  | incr_indexes (Ts, k) t =
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  let
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    val n = length Ts;
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    val incrT = if k = 0 then I else incrT k;
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    fun incr lev (Var ((x, i), T)) =
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          combound (Var ((x, i + k), Ts ---> (incrT T handle SAME => T)), lev, n)
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      | incr lev (Abs (x, T, body)) =
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          (Abs (x, incrT T, incr (lev + 1) body handle SAME => body)
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            handle SAME => Abs (x, T, incr (lev + 1) body))
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      | incr lev (t $ u) =
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          (incr lev t $ (incr lev u handle SAME => u)
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            handle SAME => t $ incr lev u)
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      | incr _ (Const (c, T)) = Const (c, incrT T)
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      | incr _ (Free (x, T)) = Free (x, incrT T)
wenzelm@16879
   340
      | incr _ (t as Bound _) = t;
wenzelm@16879
   341
  in incr 0 t handle SAME => t end;
wenzelm@16879
   342
wenzelm@16879
   343
fun incr_tvar 0 T = T
wenzelm@16879
   344
  | incr_tvar k T = incrT k T handle SAME => T;
wenzelm@16879
   345
wenzelm@16879
   346
end;
wenzelm@16879
   347
clasohm@0
   348
wenzelm@18248
   349
(* Lifting functions from subgoal and increment:
wenzelm@18029
   350
    lift_abs operates on terms
wenzelm@18029
   351
    lift_all operates on propositions *)
wenzelm@18029
   352
wenzelm@18029
   353
fun lift_abs inc =
wenzelm@18029
   354
  let
wenzelm@18029
   355
    fun lift Ts (Const ("==>", _) $ _ $ B) t = lift Ts B t
wenzelm@18248
   356
      | lift Ts (Const ("all", _) $ Abs (a, T, B)) t = Abs (a, T, lift (T :: Ts) B t)
wenzelm@18029
   357
      | lift Ts _ t = incr_indexes (rev Ts, inc) t;
wenzelm@18029
   358
  in lift [] end;
wenzelm@18029
   359
wenzelm@18029
   360
fun lift_all inc =
wenzelm@18029
   361
  let
wenzelm@18029
   362
    fun lift Ts ((c as Const ("==>", _)) $ A $ B) t = c $ A $ lift Ts B t
wenzelm@18248
   363
      | lift Ts ((c as Const ("all", _)) $ Abs (a, T, B)) t = c $ Abs (a, T, lift (T :: Ts) B t)
wenzelm@18029
   364
      | lift Ts _ t = incr_indexes (rev Ts, inc) t;
wenzelm@18029
   365
  in lift [] end;
clasohm@0
   366
clasohm@0
   367
(*Strips assumptions in goal, yielding list of hypotheses.   *)
berghofe@21016
   368
fun strip_assums_hyp B =
berghofe@21016
   369
  let
berghofe@21016
   370
    fun strip Hs (Const ("==>", _) $ H $ B) = strip (H :: Hs) B
berghofe@21016
   371
      | strip Hs (Const ("all", _) $ Abs (a, T, t)) =
berghofe@21016
   372
          strip (map (incr_boundvars 1) Hs) t
berghofe@21016
   373
      | strip Hs B = rev Hs
berghofe@21016
   374
  in strip [] B end;
clasohm@0
   375
clasohm@0
   376
(*Strips assumptions in goal, yielding conclusion.   *)
clasohm@0
   377
fun strip_assums_concl (Const("==>", _) $ H $ B) = strip_assums_concl B
clasohm@0
   378
  | strip_assums_concl (Const("all",_)$Abs(a,T,t)) = strip_assums_concl t
clasohm@0
   379
  | strip_assums_concl B = B;
clasohm@0
   380
clasohm@0
   381
(*Make a list of all the parameters in a subgoal, even if nested*)
clasohm@0
   382
fun strip_params (Const("==>", _) $ H $ B) = strip_params B
clasohm@0
   383
  | strip_params (Const("all",_)$Abs(a,T,t)) = (a,T) :: strip_params t
clasohm@0
   384
  | strip_params B = [];
clasohm@0
   385
wenzelm@23597
   386
(*test for nested meta connectives in prems*)
wenzelm@23597
   387
val has_meta_prems =
wenzelm@9667
   388
  let
wenzelm@23597
   389
    fun is_meta (Const ("==", _) $ _ $ _) = true
wenzelm@23597
   390
      | is_meta (Const ("==>", _) $ _ $ _) = true
wenzelm@9667
   391
      | is_meta (Const ("all", _) $ _) = true
wenzelm@9667
   392
      | is_meta _ = false;
wenzelm@23597
   393
    fun ex_meta (Const ("==>", _) $ A $ B) = is_meta A orelse ex_meta B
wenzelm@23597
   394
      | ex_meta (Const ("all", _) $ Abs (_, _, B)) = ex_meta B
wenzelm@23597
   395
      | ex_meta _ = false;
wenzelm@23597
   396
  in ex_meta end;
wenzelm@9483
   397
clasohm@0
   398
(*Removes the parameters from a subgoal and renumber bvars in hypotheses,
wenzelm@9460
   399
    where j is the total number of parameters (precomputed)
clasohm@0
   400
  If n>0 then deletes assumption n. *)
wenzelm@9460
   401
fun remove_params j n A =
clasohm@0
   402
    if j=0 andalso n<=0 then A  (*nothing left to do...*)
clasohm@0
   403
    else case A of
wenzelm@9460
   404
        Const("==>", _) $ H $ B =>
wenzelm@9460
   405
          if n=1 then                           (remove_params j (n-1) B)
wenzelm@9460
   406
          else implies $ (incr_boundvars j H) $ (remove_params j (n-1) B)
clasohm@0
   407
      | Const("all",_)$Abs(a,T,t) => remove_params (j-1) n t
clasohm@0
   408
      | _ => if n>0 then raise TERM("remove_params", [A])
clasohm@0
   409
             else A;
clasohm@0
   410
clasohm@0
   411
(*Move all parameters to the front of the subgoal, renaming them apart;
clasohm@0
   412
  if n>0 then deletes assumption n. *)
clasohm@0
   413
fun flatten_params n A =
clasohm@0
   414
    let val params = strip_params A;
berghofe@25939
   415
        val vars = ListPair.zip (Name.variant_list [] (map #1 params),
berghofe@25939
   416
                                 map #2 params)
clasohm@0
   417
    in  list_all (vars, remove_params (length vars) n A)
clasohm@0
   418
    end;
clasohm@0
   419
clasohm@0
   420
(*Makes parameters in a goal have the names supplied by the list cs.*)
clasohm@0
   421
fun list_rename_params (cs, Const("==>", _) $ A $ B) =
clasohm@0
   422
      implies $ A $ list_rename_params (cs, B)
wenzelm@27334
   423
  | list_rename_params (c::cs, (a as Const("all",_)) $ Abs(_,T,t)) =
wenzelm@27334
   424
      a $ Abs(c, T, list_rename_params (cs, t))
clasohm@0
   425
  | list_rename_params (cs, B) = B;
clasohm@0
   426
wenzelm@19806
   427
(*** Treatment of "assume", "erule", etc. ***)
clasohm@0
   428
wenzelm@16879
   429
(*Strips assumptions in goal yielding
paulson@15451
   430
   HS = [Hn,...,H1],   params = [xm,...,x1], and B,
wenzelm@16879
   431
  where x1...xm are the parameters. This version (21.1.2005) REQUIRES
wenzelm@16879
   432
  the the parameters to be flattened, but it allows erule to work on
paulson@15451
   433
  assumptions of the form !!x. phi. Any !! after the outermost string
paulson@15451
   434
  will be regarded as belonging to the conclusion, and left untouched.
paulson@15454
   435
  Used ONLY by assum_pairs.
paulson@15454
   436
      Unless nasms<0, it can terminate the recursion early; that allows
paulson@15454
   437
  erule to work on assumptions of the form P==>Q.*)
paulson@15454
   438
fun strip_assums_imp (0, Hs, B) = (Hs, B)  (*recursion terminated by nasms*)
wenzelm@16879
   439
  | strip_assums_imp (nasms, Hs, Const("==>", _) $ H $ B) =
paulson@15454
   440
      strip_assums_imp (nasms-1, H::Hs, B)
paulson@15454
   441
  | strip_assums_imp (_, Hs, B) = (Hs, B); (*recursion terminated by B*)
paulson@15454
   442
clasohm@0
   443
paulson@15451
   444
(*Strips OUTER parameters only, unlike similar legacy versions.*)
paulson@15451
   445
fun strip_assums_all (params, Const("all",_)$Abs(a,T,t)) =
paulson@15451
   446
      strip_assums_all ((a,T)::params, t)
paulson@15451
   447
  | strip_assums_all (params, B) = (params, B);
clasohm@0
   448
clasohm@0
   449
(*Produces disagreement pairs, one for each assumption proof, in order.
clasohm@0
   450
  A is the first premise of the lifted rule, and thus has the form
paulson@15454
   451
    H1 ==> ... Hk ==> B   and the pairs are (H1,B),...,(Hk,B).
paulson@15454
   452
  nasms is the number of assumptions in the original subgoal, needed when B
paulson@15454
   453
    has the form B1 ==> B2: it stops B1 from being taken as an assumption. *)
paulson@15454
   454
fun assum_pairs(nasms,A) =
paulson@15451
   455
  let val (params, A') = strip_assums_all ([],A)
paulson@15454
   456
      val (Hs,B) = strip_assums_imp (nasms,[],A')
wenzelm@18938
   457
      fun abspar t = rlist_abs(params, t)
paulson@15451
   458
      val D = abspar B
paulson@15451
   459
      fun pairrev ([], pairs) = pairs
paulson@15451
   460
        | pairrev (H::Hs, pairs) = pairrev(Hs,  (abspar H, D) :: pairs)
paulson@15451
   461
  in  pairrev (Hs,[])
clasohm@0
   462
  end;
clasohm@0
   463
wenzelm@30554
   464
fun assum_problems (nasms, A) =
wenzelm@30554
   465
  let
wenzelm@30554
   466
    val (params, A') = strip_assums_all ([], A)
wenzelm@30554
   467
    val (Hs, B) = strip_assums_imp (nasms, [], A')
wenzelm@30554
   468
    fun abspar t = rlist_abs (params, t)
wenzelm@30554
   469
  in (abspar, rev Hs, B) end;
wenzelm@30554
   470
wenzelm@19806
   471
wenzelm@19806
   472
(* global schematic variables *)
wenzelm@19806
   473
wenzelm@19806
   474
fun bad_schematic xi = "Illegal schematic variable: " ^ quote (Term.string_of_vname xi);
wenzelm@19806
   475
fun bad_fixed x = "Illegal fixed variable: " ^ quote x;
wenzelm@19806
   476
wenzelm@31981
   477
fun varifyT_option ty = ty
wenzelm@31981
   478
  |> Term_Subst.map_atypsT_option
wenzelm@31981
   479
    (fn TFree (a, S) => SOME (TVar ((a, 0), S))
wenzelm@31981
   480
      | TVar (ai, _) => raise TYPE (bad_schematic ai, [ty], []));
wenzelm@19806
   481
wenzelm@31981
   482
fun unvarifyT_option ty = ty
wenzelm@31981
   483
  |> Term_Subst.map_atypsT_option
wenzelm@31981
   484
    (fn TVar ((a, 0), S) => SOME (TFree (a, S))
wenzelm@31981
   485
      | TVar (ai, _) => raise TYPE (bad_schematic ai, [ty], [])
wenzelm@31981
   486
      | TFree (a, _) => raise TYPE (bad_fixed a, [ty], []));
clasohm@0
   487
wenzelm@31981
   488
val varifyT = perhaps varifyT_option;
wenzelm@31981
   489
val unvarifyT = perhaps unvarifyT_option;
wenzelm@31981
   490
wenzelm@31981
   491
fun varify tm = tm
wenzelm@31981
   492
  |> perhaps (Term_Subst.map_aterms_option
wenzelm@31981
   493
    (fn Free (x, T) => SOME (Var ((x, 0), T))
wenzelm@19806
   494
      | Var (xi, _) => raise TERM (bad_schematic xi, [tm])
wenzelm@31981
   495
      | _ => NONE))
wenzelm@31981
   496
  |> perhaps (Term_Subst.map_types_option varifyT_option)
wenzelm@19879
   497
  handle TYPE (msg, _, _) => raise TERM (msg, [tm]);
wenzelm@19806
   498
wenzelm@31981
   499
fun unvarify tm = tm
wenzelm@31981
   500
  |> perhaps (Term_Subst.map_aterms_option
wenzelm@31981
   501
    (fn Var ((x, 0), T) => SOME (Free (x, T))
wenzelm@19806
   502
      | Var (xi, _) => raise TERM (bad_schematic xi, [tm])
wenzelm@19806
   503
      | Free (x, _) => raise TERM (bad_fixed x, [tm])
wenzelm@31981
   504
      | _ => NONE))
wenzelm@31981
   505
  |> perhaps (Term_Subst.map_types_option unvarifyT_option)
wenzelm@19879
   506
  handle TYPE (msg, _, _) => raise TERM (msg, [tm]);
wenzelm@19806
   507
wenzelm@19806
   508
val legacy_varifyT = Term.map_atyps (fn TFree (a, S) => TVar ((a, 0), S) | T => T);
wenzelm@19806
   509
wenzelm@19806
   510
val legacy_varify =
wenzelm@19806
   511
  Term.map_aterms (fn Free (x, T) => Var ((x, 0), T) | t => t) #>
wenzelm@20548
   512
  Term.map_types legacy_varifyT;
wenzelm@19806
   513
berghofe@13799
   514
wenzelm@16862
   515
(* goal states *)
wenzelm@16862
   516
wenzelm@16862
   517
fun get_goal st i = nth_prem (i, st)
wenzelm@16862
   518
  handle TERM _ => error "Goal number out of range";
berghofe@13799
   519
berghofe@13799
   520
(*reverses parameters for substitution*)
berghofe@13799
   521
fun goal_params st i =
berghofe@13799
   522
  let val gi = get_goal st i
wenzelm@29276
   523
      val rfrees = map Free (Term.rename_wrt_term gi (strip_params gi))
berghofe@13799
   524
  in (gi, rfrees) end;
berghofe@13799
   525
berghofe@13799
   526
fun concl_of_goal st i =
berghofe@13799
   527
  let val (gi, rfrees) = goal_params st i
berghofe@13799
   528
      val B = strip_assums_concl gi
berghofe@13799
   529
  in subst_bounds (rfrees, B) end;
berghofe@13799
   530
berghofe@13799
   531
fun prems_of_goal st i =
berghofe@13799
   532
  let val (gi, rfrees) = goal_params st i
berghofe@13799
   533
      val As = strip_assums_hyp gi
berghofe@13799
   534
  in map (fn A => subst_bounds (rfrees, A)) As end;
berghofe@13799
   535
clasohm@0
   536
end;