src/Pure/tactic.ML
author nipkow
Mon Sep 09 18:53:41 1996 +0200 (1996-09-09)
changeset 1966 9e626f86e335
parent 1955 5309416236b6
child 1975 eec67972b1bf
permissions -rw-r--r--
added cterm_lift_inst_rule
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(*  Title: 	tactic
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    ID:         $Id$
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    Author: 	Lawrence C Paulson, Cambridge University Computer Laboratory
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    Copyright   1991  University of Cambridge
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Tactics 
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*)
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signature TACTIC =
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  sig
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  val ares_tac: thm list -> int -> tactic
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  val asm_rewrite_goal_tac:
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        bool*bool -> (meta_simpset -> tactic) -> meta_simpset -> int -> tactic
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  val assume_tac: int -> tactic
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  val atac: int ->tactic
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  val bimatch_from_nets_tac: 
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      (int*(bool*thm)) Net.net * (int*(bool*thm)) Net.net -> int -> tactic
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  val bimatch_tac: (bool*thm)list -> int -> tactic
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  val biresolve_from_nets_tac: 
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      (int*(bool*thm)) Net.net * (int*(bool*thm)) Net.net -> int -> tactic
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  val biresolve_tac: (bool*thm)list -> int -> tactic
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  val build_net: thm list -> (int*thm) Net.net
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  val build_netpair:    (int*(bool*thm)) Net.net * (int*(bool*thm)) Net.net ->
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      (bool*thm)list -> (int*(bool*thm)) Net.net * (int*(bool*thm)) Net.net
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  val compose_inst_tac: (string*string)list -> (bool*thm*int) -> int -> tactic
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  val compose_tac: (bool * thm * int) -> int -> tactic 
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  val cterm_lift_inst_rule:
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      thm * int * (indexname*ctyp)list * (term*cterm)list  * thm -> thm
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  val cut_facts_tac: thm list -> int -> tactic
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  val cut_inst_tac: (string*string)list -> thm -> int -> tactic   
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  val dmatch_tac: thm list -> int -> tactic
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  val dresolve_tac: thm list -> int -> tactic
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  val dres_inst_tac: (string*string)list -> thm -> int -> tactic   
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  val dtac: thm -> int ->tactic
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  val etac: thm -> int ->tactic
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  val eq_assume_tac: int -> tactic   
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  val ematch_tac: thm list -> int -> tactic
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  val eresolve_tac: thm list -> int -> tactic
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  val eres_inst_tac: (string*string)list -> thm -> int -> tactic   
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  val filter_thms: (term*term->bool) -> int*term*thm list -> thm list
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  val filt_resolve_tac: thm list -> int -> int -> tactic
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  val flexflex_tac: tactic
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  val fold_goals_tac: thm list -> tactic
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  val fold_tac: thm list -> tactic
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  val forward_tac: thm list -> int -> tactic   
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  val forw_inst_tac: (string*string)list -> thm -> int -> tactic
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  val freeze: thm -> thm   
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  val insert_tagged_brl:  ('a*(bool*thm)) * 
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                    (('a*(bool*thm))Net.net * ('a*(bool*thm))Net.net) ->
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                    ('a*(bool*thm))Net.net * ('a*(bool*thm))Net.net
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  val delete_tagged_brl:  (bool*thm) * 
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                    ((int*(bool*thm))Net.net * (int*(bool*thm))Net.net) ->
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                    (int*(bool*thm))Net.net * (int*(bool*thm))Net.net
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  val is_fact: thm -> bool
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  val lessb: (bool * thm) * (bool * thm) -> bool
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  val lift_inst_rule: thm * int * (string*string)list * thm -> thm
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  val make_elim: thm -> thm
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  val match_from_net_tac: (int*thm) Net.net -> int -> tactic
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  val match_tac: thm list -> int -> tactic
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  val metacut_tac: thm -> int -> tactic   
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  val net_bimatch_tac: (bool*thm) list -> int -> tactic
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  val net_biresolve_tac: (bool*thm) list -> int -> tactic
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  val net_match_tac: thm list -> int -> tactic
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  val net_resolve_tac: thm list -> int -> tactic
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  val PRIMITIVE: (thm -> thm) -> tactic  
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  val PRIMSEQ: (thm -> thm Sequence.seq) -> tactic  
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  val prune_params_tac: tactic
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  val rename_tac: string -> int -> tactic
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  val rename_last_tac: string -> string list -> int -> tactic
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  val resolve_from_net_tac: (int*thm) Net.net -> int -> tactic
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  val resolve_tac: thm list -> int -> tactic
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  val res_inst_tac: (string*string)list -> thm -> int -> tactic   
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  val rewrite_goals_tac: thm list -> tactic
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  val rewrite_tac: thm list -> tactic
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  val rewtac: thm -> tactic
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  val rotate_tac: int -> int -> tactic
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  val rtac: thm -> int -> tactic
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  val rule_by_tactic: tactic -> thm -> thm
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  val subgoal_tac: string -> int -> tactic
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  val subgoals_tac: string list -> int -> tactic
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  val subgoals_of_brl: bool * thm -> int
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  val thin_tac: string -> int -> tactic
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  val trace_goalno_tac: (int -> tactic) -> int -> tactic
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  end;
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structure Tactic : TACTIC = 
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struct
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(*Discover which goal is chosen:  SOMEGOAL(trace_goalno_tac tac) *)
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fun trace_goalno_tac tac i st =  
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    case Sequence.pull(tac i st) of
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	None    => Sequence.null
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      | seqcell => (prs("Subgoal " ^ string_of_int i ^ " selected\n"); 
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    			 Sequence.seqof(fn()=> seqcell));
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fun string_of (a,0) = a
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  | string_of (a,i) = a ^ "_" ^ string_of_int i;
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(*convert all Vars in a theorem to Frees*)
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fun freeze th =
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  let val fth = freezeT th
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      val {prop,sign,...} = rep_thm fth
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      fun mk_inst (Var(v,T)) = 
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	  (cterm_of sign (Var(v,T)),
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	   cterm_of sign (Free(string_of v, T)))
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      val insts = map mk_inst (term_vars prop)
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  in  instantiate ([],insts) fth  end;
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(*Makes a rule by applying a tactic to an existing rule*)
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fun rule_by_tactic tac rl =
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    case Sequence.pull(tac (freeze (standard rl))) of
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	None        => raise THM("rule_by_tactic", 0, [rl])
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      | Some(rl',_) => standard rl';
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(*** Basic tactics ***)
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(*Makes a tactic whose effect on a state is given by thmfun: thm->thm seq.*)
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fun PRIMSEQ thmfun st =  thmfun st handle THM _ => Sequence.null;
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(*Makes a tactic whose effect on a state is given by thmfun: thm->thm.*)
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fun PRIMITIVE thmfun = PRIMSEQ (Sequence.single o thmfun);
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(*** The following fail if the goal number is out of range:
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     thus (REPEAT (resolve_tac rules i)) stops once subgoal i disappears. *)
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(*Solve subgoal i by assumption*)
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fun assume_tac i = PRIMSEQ (assumption i);
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(*Solve subgoal i by assumption, using no unification*)
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fun eq_assume_tac i = PRIMITIVE (eq_assumption i);
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(** Resolution/matching tactics **)
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(*The composition rule/state: no lifting or var renaming.
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  The arg = (bires_flg, orule, m) ;  see bicompose for explanation.*)
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fun compose_tac arg i = PRIMSEQ (bicompose false arg i);
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(*Converts a "destruct" rule like P&Q==>P to an "elimination" rule
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  like [| P&Q; P==>R |] ==> R *)
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fun make_elim rl = zero_var_indexes (rl RS revcut_rl);
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(*Attack subgoal i by resolution, using flags to indicate elimination rules*)
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fun biresolve_tac brules i = PRIMSEQ (biresolution false brules i);
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(*Resolution: the simple case, works for introduction rules*)
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fun resolve_tac rules = biresolve_tac (map (pair false) rules);
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(*Resolution with elimination rules only*)
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fun eresolve_tac rules = biresolve_tac (map (pair true) rules);
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(*Forward reasoning using destruction rules.*)
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fun forward_tac rls = resolve_tac (map make_elim rls) THEN' assume_tac;
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(*Like forward_tac, but deletes the assumption after use.*)
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fun dresolve_tac rls = eresolve_tac (map make_elim rls);
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(*Shorthand versions: for resolution with a single theorem*)
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fun rtac rl = resolve_tac [rl];
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fun etac rl = eresolve_tac [rl];
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fun dtac rl = dresolve_tac [rl];
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val atac = assume_tac;
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(*Use an assumption or some rules ... A popular combination!*)
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fun ares_tac rules = assume_tac  ORELSE'  resolve_tac rules;
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(*Matching tactics -- as above, but forbid updating of state*)
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fun bimatch_tac brules i = PRIMSEQ (biresolution true brules i);
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fun match_tac rules  = bimatch_tac (map (pair false) rules);
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fun ematch_tac rules = bimatch_tac (map (pair true) rules);
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fun dmatch_tac rls   = ematch_tac (map make_elim rls);
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(*Smash all flex-flex disagreement pairs in the proof state.*)
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val flexflex_tac = PRIMSEQ flexflex_rule;
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(*Lift and instantiate a rule wrt the given state and subgoal number *)
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fun lift_inst_rule (st, i, sinsts, rule) =
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let val {maxidx,sign,...} = rep_thm st
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    val (_, _, Bi, _) = dest_state(st,i)
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    val params = Logic.strip_params Bi	        (*params of subgoal i*)
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    val params = rev(rename_wrt_term Bi params) (*as they are printed*)
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    val paramTs = map #2 params
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    and inc = maxidx+1
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    fun liftvar (Var ((a,j), T)) = Var((a, j+inc), paramTs---> incr_tvar inc T)
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      | liftvar t = raise TERM("Variable expected", [t]);
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    fun liftterm t = list_abs_free (params, 
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				    Logic.incr_indexes(paramTs,inc) t)
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    (*Lifts instantiation pair over params*)
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    fun liftpair (cv,ct) = (cterm_fun liftvar cv, cterm_fun liftterm ct)
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    fun lifttvar((a,i),ctyp) =
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	let val {T,sign} = rep_ctyp ctyp
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	in  ((a,i+inc), ctyp_of sign (incr_tvar inc T)) end
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    val rts = types_sorts rule and (types,sorts) = types_sorts st
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    fun types'(a,~1) = (case assoc(params,a) of None => types(a,~1) | sm => sm)
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      | types'(ixn) = types ixn;
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    val used = add_term_tvarnames
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                  (#prop(rep_thm st) $ #prop(rep_thm rule),[])
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    val (Tinsts,insts) = read_insts sign rts (types',sorts) used sinsts
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in instantiate (map lifttvar Tinsts, map liftpair insts)
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               (lift_rule (st,i) rule)
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end;
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(*Like lift_inst_rule but takes cterms, not strings.
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  The cterms must be functions of the parameters of the subgoal,
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  i.e. they are assumed to be lifted already!
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  Also: types of Vars must be fully instantiated already *)
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fun cterm_lift_inst_rule (st, i, Tinsts, insts, rule) =
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let val {maxidx,sign,...} = rep_thm st
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    val (_, _, Bi, _) = dest_state(st,i)
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    val params = Logic.strip_params Bi          (*params of subgoal i*)
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    val paramTs = map #2 params
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    and inc = maxidx+1
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    fun liftvar (Var ((a,j), T)) =
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          cterm_of sign (Var((a, j+inc), paramTs---> incr_tvar inc T))
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      | liftvar t = raise TERM("Variable expected", [t]);
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    (*lift only Var, not cterm! Must to be lifted already*)
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    fun liftpair (v,ct) = (liftvar v, ct)
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    fun lifttvar((a,i),ctyp) =
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        let val {T,sign} = rep_ctyp ctyp
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        in  ((a,i+inc), ctyp_of sign (incr_tvar inc T)) end
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in instantiate (map lifttvar Tinsts, map liftpair insts)
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               (lift_rule (st,i) rule)
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end;
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(*** Resolve after lifting and instantation; may refer to parameters of the
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     subgoal.  Fails if "i" is out of range.  ***)
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(*compose version: arguments are as for bicompose.*)
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fun compose_inst_tac sinsts (bires_flg, rule, nsubgoal) i =
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  STATE ( fn st => 
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	   compose_tac (bires_flg, lift_inst_rule (st, i, sinsts, rule),
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			nsubgoal) i
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	   handle TERM (msg,_) => (writeln msg;  no_tac)
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		| THM  (msg,_,_) => (writeln msg;  no_tac) );
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(*"Resolve" version.  Note: res_inst_tac cannot behave sensibly if the
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  terms that are substituted contain (term or type) unknowns from the
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  goal, because it is unable to instantiate goal unknowns at the same time.
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  The type checker is instructed not to freezes flexible type vars that
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  were introduced during type inference and still remain in the term at the
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  end.  This increases flexibility but can introduce schematic type vars in
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  goals.
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*)
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fun res_inst_tac sinsts rule i =
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    compose_inst_tac sinsts (false, rule, nprems_of rule) i;
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(*eresolve elimination version*)
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fun eres_inst_tac sinsts rule i =
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    compose_inst_tac sinsts (true, rule, nprems_of rule) i;
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(*For forw_inst_tac and dres_inst_tac.  Preserve Var indexes of rl;
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  increment revcut_rl instead.*)
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fun make_elim_preserve rl = 
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  let val {maxidx,...} = rep_thm rl
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      fun cvar ixn = cterm_of Sign.proto_pure (Var(ixn,propT));
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      val revcut_rl' = 
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	  instantiate ([],  [(cvar("V",0), cvar("V",maxidx+1)),
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			     (cvar("W",0), cvar("W",maxidx+1))]) revcut_rl
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      val arg = (false, rl, nprems_of rl)
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      val [th] = Sequence.list_of_s (bicompose false arg 1 revcut_rl')
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  in  th  end
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  handle Bind => raise THM("make_elim_preserve", 1, [rl]);
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(*instantiate and cut -- for a FACT, anyway...*)
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fun cut_inst_tac sinsts rule = res_inst_tac sinsts (make_elim_preserve rule);
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(*forward tactic applies a RULE to an assumption without deleting it*)
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fun forw_inst_tac sinsts rule = cut_inst_tac sinsts rule THEN' assume_tac;
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(*dresolve tactic applies a RULE to replace an assumption*)
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fun dres_inst_tac sinsts rule = eres_inst_tac sinsts (make_elim_preserve rule);
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(*Deletion of an assumption*)
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fun thin_tac s = eres_inst_tac [("V",s)] thin_rl;
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(*** Applications of cut_rl ***)
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(*Used by metacut_tac*)
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fun bires_cut_tac arg i =
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    resolve_tac [cut_rl] i  THEN  biresolve_tac arg (i+1) ;
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(*The conclusion of the rule gets assumed in subgoal i,
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  while subgoal i+1,... are the premises of the rule.*)
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fun metacut_tac rule = bires_cut_tac [(false,rule)];
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(*Recognizes theorems that are not rules, but simple propositions*)
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fun is_fact rl =
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    case prems_of rl of
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	[] => true  |  _::_ => false;
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(*"Cut" all facts from theorem list into the goal as assumptions. *)
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fun cut_facts_tac ths i =
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    EVERY (map (fn th => metacut_tac th i) (filter is_fact ths));
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(*Introduce the given proposition as a lemma and subgoal*)
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fun subgoal_tac sprop = res_inst_tac [("psi", sprop)] cut_rl;
clasohm@0
   298
lcp@439
   299
(*Introduce a list of lemmas and subgoals*)
lcp@439
   300
fun subgoals_tac sprops = EVERY' (map subgoal_tac sprops);
lcp@439
   301
clasohm@0
   302
clasohm@0
   303
(**** Indexing and filtering of theorems ****)
clasohm@0
   304
clasohm@0
   305
(*Returns the list of potentially resolvable theorems for the goal "prem",
clasohm@1460
   306
	using the predicate  could(subgoal,concl).
clasohm@0
   307
  Resulting list is no longer than "limit"*)
clasohm@0
   308
fun filter_thms could (limit, prem, ths) =
clasohm@0
   309
  let val pb = Logic.strip_assums_concl prem;   (*delete assumptions*)
clasohm@0
   310
      fun filtr (limit, []) = []
clasohm@1460
   311
	| filtr (limit, th::ths) =
clasohm@1460
   312
	    if limit=0 then  []
clasohm@1460
   313
	    else if could(pb, concl_of th)  then th :: filtr(limit-1, ths)
clasohm@1460
   314
	    else filtr(limit,ths)
clasohm@0
   315
  in  filtr(limit,ths)  end;
clasohm@0
   316
clasohm@0
   317
clasohm@0
   318
(*** biresolution and resolution using nets ***)
clasohm@0
   319
clasohm@0
   320
(** To preserve the order of the rules, tag them with increasing integers **)
clasohm@0
   321
clasohm@0
   322
(*insert tags*)
clasohm@0
   323
fun taglist k [] = []
clasohm@0
   324
  | taglist k (x::xs) = (k,x) :: taglist (k+1) xs;
clasohm@0
   325
clasohm@0
   326
(*remove tags and suppress duplicates -- list is assumed sorted!*)
clasohm@0
   327
fun untaglist [] = []
clasohm@0
   328
  | untaglist [(k:int,x)] = [x]
clasohm@0
   329
  | untaglist ((k,x) :: (rest as (k',x')::_)) =
clasohm@0
   330
      if k=k' then untaglist rest
clasohm@0
   331
      else    x :: untaglist rest;
clasohm@0
   332
clasohm@0
   333
(*return list elements in original order*)
clasohm@0
   334
val orderlist = untaglist o sort (fn(x,y)=> #1 x < #1 y); 
clasohm@0
   335
clasohm@0
   336
(*insert one tagged brl into the pair of nets*)
lcp@1077
   337
fun insert_tagged_brl (kbrl as (k,(eres,th)), (inet,enet)) =
clasohm@0
   338
    if eres then 
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   339
	case prems_of th of
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   340
	    prem::_ => (inet, Net.insert_term ((prem,kbrl), enet, K false))
clasohm@1460
   341
	  | [] => error"insert_tagged_brl: elimination rule with no premises"
clasohm@0
   342
    else (Net.insert_term ((concl_of th, kbrl), inet, K false), enet);
clasohm@0
   343
clasohm@0
   344
(*build a pair of nets for biresolution*)
lcp@670
   345
fun build_netpair netpair brls = 
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   346
    foldr insert_tagged_brl (taglist 1 brls, netpair);
clasohm@0
   347
paulson@1801
   348
(*delete one kbrl from the pair of nets;
paulson@1801
   349
  we don't know the value of k, so we use 0 and ignore it in the comparison*)
paulson@1801
   350
local
paulson@1801
   351
  fun eq_kbrl ((k,(eres,th)), (k',(eres',th'))) = eq_thm (th,th')
paulson@1801
   352
in
paulson@1801
   353
fun delete_tagged_brl (brl as (eres,th), (inet,enet)) =
paulson@1801
   354
    if eres then 
paulson@1801
   355
	case prems_of th of
paulson@1801
   356
	    prem::_ => (inet, Net.delete_term ((prem, (0,brl)), enet, eq_kbrl))
paulson@1801
   357
	  | [] => error"delete_brl: elimination rule with no premises"
paulson@1801
   358
    else (Net.delete_term ((concl_of th, (0,brl)), inet, eq_kbrl), enet);
paulson@1801
   359
end;
paulson@1801
   360
paulson@1801
   361
clasohm@0
   362
(*biresolution using a pair of nets rather than rules*)
clasohm@0
   363
fun biresolution_from_nets_tac match (inet,enet) =
clasohm@0
   364
  SUBGOAL
clasohm@0
   365
    (fn (prem,i) =>
clasohm@0
   366
      let val hyps = Logic.strip_assums_hyp prem
clasohm@0
   367
          and concl = Logic.strip_assums_concl prem 
clasohm@0
   368
          val kbrls = Net.unify_term inet concl @
clasohm@0
   369
                      flat (map (Net.unify_term enet) hyps)
clasohm@0
   370
      in PRIMSEQ (biresolution match (orderlist kbrls) i) end);
clasohm@0
   371
clasohm@0
   372
(*versions taking pre-built nets*)
clasohm@0
   373
val biresolve_from_nets_tac = biresolution_from_nets_tac false;
clasohm@0
   374
val bimatch_from_nets_tac = biresolution_from_nets_tac true;
clasohm@0
   375
clasohm@0
   376
(*fast versions using nets internally*)
lcp@670
   377
val net_biresolve_tac =
lcp@670
   378
    biresolve_from_nets_tac o build_netpair(Net.empty,Net.empty);
lcp@670
   379
lcp@670
   380
val net_bimatch_tac =
lcp@670
   381
    bimatch_from_nets_tac o build_netpair(Net.empty,Net.empty);
clasohm@0
   382
clasohm@0
   383
(*** Simpler version for resolve_tac -- only one net, and no hyps ***)
clasohm@0
   384
clasohm@0
   385
(*insert one tagged rl into the net*)
clasohm@0
   386
fun insert_krl (krl as (k,th), net) =
clasohm@0
   387
    Net.insert_term ((concl_of th, krl), net, K false);
clasohm@0
   388
clasohm@0
   389
(*build a net of rules for resolution*)
clasohm@0
   390
fun build_net rls = 
clasohm@0
   391
    foldr insert_krl (taglist 1 rls, Net.empty);
clasohm@0
   392
clasohm@0
   393
(*resolution using a net rather than rules; pred supports filt_resolve_tac*)
clasohm@0
   394
fun filt_resolution_from_net_tac match pred net =
clasohm@0
   395
  SUBGOAL
clasohm@0
   396
    (fn (prem,i) =>
clasohm@0
   397
      let val krls = Net.unify_term net (Logic.strip_assums_concl prem)
clasohm@0
   398
      in 
clasohm@1460
   399
	 if pred krls  
clasohm@0
   400
         then PRIMSEQ
clasohm@1460
   401
		(biresolution match (map (pair false) (orderlist krls)) i)
clasohm@0
   402
         else no_tac
clasohm@0
   403
      end);
clasohm@0
   404
clasohm@0
   405
(*Resolve the subgoal using the rules (making a net) unless too flexible,
clasohm@0
   406
   which means more than maxr rules are unifiable.      *)
clasohm@0
   407
fun filt_resolve_tac rules maxr = 
clasohm@0
   408
    let fun pred krls = length krls <= maxr
clasohm@0
   409
    in  filt_resolution_from_net_tac false pred (build_net rules)  end;
clasohm@0
   410
clasohm@0
   411
(*versions taking pre-built nets*)
clasohm@0
   412
val resolve_from_net_tac = filt_resolution_from_net_tac false (K true);
clasohm@0
   413
val match_from_net_tac = filt_resolution_from_net_tac true (K true);
clasohm@0
   414
clasohm@0
   415
(*fast versions using nets internally*)
clasohm@0
   416
val net_resolve_tac = resolve_from_net_tac o build_net;
clasohm@0
   417
val net_match_tac = match_from_net_tac o build_net;
clasohm@0
   418
clasohm@0
   419
clasohm@0
   420
(*** For Natural Deduction using (bires_flg, rule) pairs ***)
clasohm@0
   421
clasohm@0
   422
(*The number of new subgoals produced by the brule*)
lcp@1077
   423
fun subgoals_of_brl (true,rule)  = nprems_of rule - 1
lcp@1077
   424
  | subgoals_of_brl (false,rule) = nprems_of rule;
clasohm@0
   425
clasohm@0
   426
(*Less-than test: for sorting to minimize number of new subgoals*)
clasohm@0
   427
fun lessb (brl1,brl2) = subgoals_of_brl brl1 < subgoals_of_brl brl2;
clasohm@0
   428
clasohm@0
   429
clasohm@0
   430
(*** Meta-Rewriting Tactics ***)
clasohm@0
   431
clasohm@0
   432
fun result1 tacf mss thm =
paulson@1501
   433
  case Sequence.pull(tacf mss thm) of
clasohm@0
   434
    None => None
clasohm@0
   435
  | Some(thm,_) => Some(thm);
clasohm@0
   436
clasohm@0
   437
(*Rewrite subgoal i only *)
nipkow@214
   438
fun asm_rewrite_goal_tac mode prover_tac mss i =
nipkow@214
   439
      PRIMITIVE(rewrite_goal_rule mode (result1 prover_tac) mss i);
clasohm@0
   440
lcp@69
   441
(*Rewrite throughout proof state. *)
lcp@69
   442
fun rewrite_tac defs = PRIMITIVE(rewrite_rule defs);
clasohm@0
   443
clasohm@0
   444
(*Rewrite subgoals only, not main goal. *)
lcp@69
   445
fun rewrite_goals_tac defs = PRIMITIVE (rewrite_goals_rule defs);
clasohm@0
   446
clasohm@1460
   447
fun rewtac def = rewrite_goals_tac [def];
clasohm@0
   448
clasohm@0
   449
paulson@1501
   450
(*** for folding definitions, handling critical pairs ***)
lcp@69
   451
lcp@69
   452
(*The depth of nesting in a term*)
lcp@69
   453
fun term_depth (Abs(a,T,t)) = 1 + term_depth t
lcp@69
   454
  | term_depth (f$t) = 1 + max [term_depth f, term_depth t]
lcp@69
   455
  | term_depth _ = 0;
lcp@69
   456
lcp@69
   457
val lhs_of_thm = #1 o Logic.dest_equals o #prop o rep_thm;
lcp@69
   458
lcp@69
   459
(*folding should handle critical pairs!  E.g. K == Inl(0),  S == Inr(Inl(0))
lcp@69
   460
  Returns longest lhs first to avoid folding its subexpressions.*)
lcp@69
   461
fun sort_lhs_depths defs =
lcp@69
   462
  let val keylist = make_keylist (term_depth o lhs_of_thm) defs
lcp@69
   463
      val keys = distinct (sort op> (map #2 keylist))
lcp@69
   464
  in  map (keyfilter keylist) keys  end;
lcp@69
   465
lcp@69
   466
fun fold_tac defs = EVERY 
lcp@69
   467
    (map rewrite_tac (sort_lhs_depths (map symmetric defs)));
lcp@69
   468
lcp@69
   469
fun fold_goals_tac defs = EVERY 
lcp@69
   470
    (map rewrite_goals_tac (sort_lhs_depths (map symmetric defs)));
lcp@69
   471
lcp@69
   472
lcp@69
   473
(*** Renaming of parameters in a subgoal
lcp@69
   474
     Names may contain letters, digits or primes and must be
lcp@69
   475
     separated by blanks ***)
clasohm@0
   476
clasohm@0
   477
(*Calling this will generate the warning "Same as previous level" since
clasohm@0
   478
  it affects nothing but the names of bound variables!*)
clasohm@0
   479
fun rename_tac str i = 
clasohm@0
   480
  let val cs = explode str 
clasohm@0
   481
  in  
clasohm@0
   482
  if !Logic.auto_rename 
clasohm@0
   483
  then (writeln"Note: setting Logic.auto_rename := false"; 
clasohm@1460
   484
	Logic.auto_rename := false)
clasohm@0
   485
  else ();
clasohm@0
   486
  case #2 (take_prefix (is_letdig orf is_blank) cs) of
clasohm@0
   487
      [] => PRIMITIVE (rename_params_rule (scanwords is_letdig cs, i))
clasohm@0
   488
    | c::_ => error ("Illegal character: " ^ c)
clasohm@0
   489
  end;
clasohm@0
   490
paulson@1501
   491
(*Rename recent parameters using names generated from a and the suffixes,
paulson@1501
   492
  provided the string a, which represents a term, is an identifier. *)
clasohm@0
   493
fun rename_last_tac a sufs i = 
clasohm@0
   494
  let val names = map (curry op^ a) sufs
clasohm@0
   495
  in  if Syntax.is_identifier a
clasohm@0
   496
      then PRIMITIVE (rename_params_rule (names,i))
clasohm@0
   497
      else all_tac
clasohm@0
   498
  end;
clasohm@0
   499
clasohm@0
   500
(*Prunes all redundant parameters from the proof state by rewriting*)
clasohm@0
   501
val prune_params_tac = rewrite_tac [triv_forall_equality];
clasohm@0
   502
paulson@1501
   503
(*rotate_tac n i: rotate the assumptions of subgoal i by n positions, from
paulson@1501
   504
  right to left if n is positive, and from left to right if n is negative.*)
nipkow@1209
   505
fun rotate_tac n =
nipkow@1209
   506
  let fun rot(n) = EVERY'(replicate n (dtac asm_rl));
nipkow@1209
   507
  in if n >= 0 then rot n
nipkow@1209
   508
     else SUBGOAL (fn (t,i) => rot(length(Logic.strip_assums_hyp t)+n) i)
nipkow@1209
   509
  end;
nipkow@1209
   510
clasohm@0
   511
end;
paulson@1501
   512
paulson@1501
   513
open Tactic;