split off modal.ML from provers.ML
authorpaulson
Tue Jul 27 19:00:55 1999 +0200 (1999-07-27)
changeset 70968c9278991d9c
parent 7095 cfc11af6174a
child 7097 5ab37ed3d53c
split off modal.ML from provers.ML
src/Sequents/modal.ML
     1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/Sequents/modal.ML	Tue Jul 27 19:00:55 1999 +0200
     1.3 @@ -0,0 +1,93 @@
     1.4 +(*  Title:      LK/modal.ML
     1.5 +    ID:         $Id$
     1.6 +    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
     1.7 +    Copyright   1992  University of Cambridge
     1.8 +
     1.9 +Simple modal reasoner
    1.10 +*)
    1.11 +
    1.12 +
    1.13 +signature MODAL_PROVER_RULE =
    1.14 +sig
    1.15 +    val rewrite_rls      : thm list
    1.16 +    val safe_rls         : thm list
    1.17 +    val unsafe_rls       : thm list
    1.18 +    val bound_rls        : thm list
    1.19 +    val aside_rls        : thm list
    1.20 +end;
    1.21 +
    1.22 +signature MODAL_PROVER = 
    1.23 +sig
    1.24 +    val rule_tac   : thm list -> int ->tactic
    1.25 +    val step_tac   : int -> tactic
    1.26 +    val solven_tac : int -> int -> tactic
    1.27 +    val solve_tac  : int -> tactic
    1.28 +end;
    1.29 +
    1.30 +functor Modal_ProverFun (Modal_Rule: MODAL_PROVER_RULE) : MODAL_PROVER = 
    1.31 +struct
    1.32 +local open Modal_Rule
    1.33 +in 
    1.34 +
    1.35 +(*Returns the list of all formulas in the sequent*)
    1.36 +fun forms_of_seq (Const("SeqO",_) $ P $ u) = P :: forms_of_seq u
    1.37 +  | forms_of_seq (H $ u) = forms_of_seq u
    1.38 +  | forms_of_seq _ = [];
    1.39 +
    1.40 +(*Tests whether two sequences (left or right sides) could be resolved.
    1.41 +  seqp is a premise (subgoal), seqc is a conclusion of an object-rule.
    1.42 +  Assumes each formula in seqc is surrounded by sequence variables
    1.43 +  -- checks that each concl formula looks like some subgoal formula.*)
    1.44 +fun could_res (seqp,seqc) =
    1.45 +      forall (fn Qc => exists (fn Qp => could_unify (Qp,Qc)) 
    1.46 +                              (forms_of_seq seqp))
    1.47 +             (forms_of_seq seqc);
    1.48 +
    1.49 +(*Tests whether two sequents G|-H could be resolved, comparing each side.*)
    1.50 +fun could_resolve_seq (prem,conc) =
    1.51 +  case (prem,conc) of
    1.52 +      (_ $ Abs(_,_,leftp) $ Abs(_,_,rightp),
    1.53 +       _ $ Abs(_,_,leftc) $ Abs(_,_,rightc)) =>
    1.54 +          could_res (leftp,leftc)  andalso  could_res (rightp,rightc)
    1.55 +    | _ => false;
    1.56 +
    1.57 +(*Like filt_resolve_tac, using could_resolve_seq
    1.58 +  Much faster than resolve_tac when there are many rules.
    1.59 +  Resolve subgoal i using the rules, unless more than maxr are compatible. *)
    1.60 +fun filseq_resolve_tac rules maxr = SUBGOAL(fn (prem,i) =>
    1.61 +  let val rls = filter_thms could_resolve_seq (maxr+1, prem, rules)
    1.62 +  in  if length rls > maxr  then  no_tac  else resolve_tac rls i
    1.63 +  end);
    1.64 +
    1.65 +fun fresolve_tac rls n = filseq_resolve_tac rls 999 n;
    1.66 +
    1.67 +(* NB No back tracking possible with aside rules *)
    1.68 +
    1.69 +fun aside_tac n = DETERM(REPEAT (filt_resolve_tac aside_rls 999 n));
    1.70 +fun rule_tac rls n = fresolve_tac rls n THEN aside_tac n;
    1.71 +
    1.72 +val fres_safe_tac = fresolve_tac safe_rls;
    1.73 +val fres_unsafe_tac = fresolve_tac unsafe_rls THEN' aside_tac;
    1.74 +val fres_bound_tac = fresolve_tac bound_rls;
    1.75 +
    1.76 +fun UPTOGOAL n tf = let fun tac i = if i<n then all_tac
    1.77 +                                    else tf(i) THEN tac(i-1)
    1.78 +                    in fn st => tac (nprems_of st) st end;
    1.79 +
    1.80 +(* Depth first search bounded by d *)
    1.81 +fun solven_tac d n state = state |>
    1.82 +       (if d<0 then no_tac
    1.83 +        else if (nprems_of state = 0) then all_tac 
    1.84 +        else (DETERM(fres_safe_tac n) THEN UPTOGOAL n (solven_tac d)) ORELSE
    1.85 +                 ((fres_unsafe_tac n  THEN UPTOGOAL n (solven_tac d)) APPEND
    1.86 +                   (fres_bound_tac n  THEN UPTOGOAL n (solven_tac (d-1)))));
    1.87 +
    1.88 +fun solve_tac d = rewrite_goals_tac rewrite_rls THEN solven_tac d 1;
    1.89 +
    1.90 +fun step_tac n = 
    1.91 +    COND (has_fewer_prems 1) all_tac 
    1.92 +         (DETERM(fres_safe_tac n) ORELSE 
    1.93 +	  (fres_unsafe_tac n APPEND fres_bound_tac n));
    1.94 +
    1.95 +end;
    1.96 +end;