src/Pure/Isar/object_logic.ML

   val fixed_judgment: Sign.sg -> string -> term
   val assert_propT: Sign.sg -> term -> term
   val declare_atomize: theory attribute
   val declare_rulify: theory attribute
   val atomize_term: Sign.sg -> term -> term
+  val atomize_thm: thm -> thm
   val atomize_rule: Sign.sg -> cterm -> thm
   val atomize_tac: int -> tactic
   val full_atomize_tac: int -> tactic
   val atomize_goal: int -> thm -> thm
   val rulify: thm -> thm

 fun atomize_term sg =
   drop_judgment sg o MetaSimplifier.rewrite_term sg (get_atomize sg) [];
 
 fun atomize_rule sg = Tactic.rewrite true (get_atomize sg);
 
+(*Convert a natural-deduction rule into a formula (probably in FOL)*)
+fun atomize_thm th =
+  rewrite_rule  (get_atomize (Thm.sign_of_thm th)) th;
+
 fun atomize_tac i st =
   if Logic.has_meta_prems (Thm.prop_of st) i then
     (rewrite_prems_tac (get_atomize (Thm.sign_of_thm st)) i) st
   else all_tac st;