src/Tools/isac/MathEngBasic/rewrite.sml
changeset 59865 75a9d629ea53
parent 59864 167472fbce77
child 59867 bb153a08645b
     1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/Tools/isac/MathEngBasic/rewrite.sml	Fri Apr 10 14:46:55 2020 +0200
     1.3 @@ -0,0 +1,342 @@
     1.4 +(* isac's rewriter
     1.5 +   (c) Walther Neuper 2000
     1.6 +*)
     1.7 +
     1.8 +signature REWRITE =
     1.9 +  sig
    1.10 +(*/------- to ThmC_Def -------\*)
    1.11 +    val assoc_thm': theory -> ThmC_Def.thm' -> thm
    1.12 +    val assoc_thm'': theory -> ThmC_Def.thmID -> thm
    1.13 +(*\------- to ThmC_Def -------/*)
    1.14 +    val calculate_: theory -> string * Exec_Def.eval_fn -> term -> (term * (string * thm)) option
    1.15 +    val eval__true: theory -> int -> term list -> (term * term) list -> Rule_Set.T -> term list * bool
    1.16 +    val eval_prog_expr: theory -> Rule_Set.T -> term -> term
    1.17 +    val eval_true_: theory -> Rule_Set.T -> term -> bool
    1.18 +    val eval_true: theory -> term list -> Rule_Set.T -> bool
    1.19 +    val rew_sub: theory -> int -> (term * term) list -> ((term * term) list -> term * term -> bool)
    1.20 +      -> Rule_Set.T -> bool -> TermC.path -> term -> term -> term * term list * TermC.path * bool
    1.21 +    val rewrite_: theory -> ((term * term) list -> term * term -> bool) -> Rule_Set.T -> bool -> thm ->
    1.22 +      term -> (term * term list) option
    1.23 +    val rewrite_inst_: theory -> ((term * term) list -> term * term -> bool) -> Rule_Set.T -> bool
    1.24 +      -> (term * term) list -> thm -> term -> (term * term list) option
    1.25 +    val rewrite_set_: theory -> bool -> Rule_Set.T -> term -> (term * term list) option
    1.26 +    val rewrite_set_inst_: theory -> bool -> (term * term) list -> Rule_Set.T -> term -> (term * term list) option
    1.27 +    val rewrite_terms_: theory -> ((term * term) list -> term * term -> bool) -> Rule_Set.T -> term list
    1.28 +      -> term -> (term * term list) option
    1.29 +(* ---- for tests only: shifted from below to remove the Warning "unused" at fun.def. --------- *)
    1.30 +  (* NONE *)
    1.31 +(*/-------------------------------------------------------- ! aktivate for Test_Isac BEGIN ---\* )
    1.32 +    val rewrite__: theory -> int -> (term * term) list -> ((term * term) list -> term * term -> bool) ->
    1.33 +      Rule_Set.T -> bool -> thm -> term -> (term * term list) option
    1.34 +    val rewrite__set_: theory -> int -> bool -> (term * term) list -> Rule_Set.T -> term -> (term * term list) option
    1.35 +    val app_rev: theory -> int -> Rule_Set.T -> term -> term * term list * bool
    1.36 +    val app_sub: theory -> int -> Rule_Set.T -> term -> term * term list * bool
    1.37 +    val mk_thm: theory -> string -> thm
    1.38 +    val trace1: int -> string -> unit
    1.39 +( *\--- ! aktivate for Test_Isac END ----------------------------------------------------------/*)
    1.40 +  end
    1.41 +
    1.42 +(**)
    1.43 +structure Rewrite(**): REWRITE(**) =
    1.44 +struct
    1.45 +(**)
    1.46 +
    1.47 +exception NO_REWRITE;
    1.48 +exception STOP_REW_SUB; (*WN050820 quick and dirty*)
    1.49 +
    1.50 +fun trace i str = 
    1.51 +  if ! Celem.trace_rewrite andalso i < ! Celem.depth then tracing (idt "#" i ^ str) else ()
    1.52 +fun trace1 i str = 
    1.53 +  if ! Celem.trace_rewrite andalso i < ! Celem.depth then tracing (idt "#" (i + 1) ^ str) else ()
    1.54 +
    1.55 +fun rewrite__ thy i bdv tless rls put_asm thm ct =
    1.56 +  let
    1.57 +    val (t', asms, _ (*lrd*), rew) = rew_sub thy i bdv tless rls put_asm ([(*root of the term*)]: TermC.path)
    1.58 +		  (((TermC.inst_bdv bdv) o Num_Calc.norm o #prop o Thm.rep_thm) thm) ct
    1.59 +  in if rew then SOME (t', distinct asms) else NONE end
    1.60 +  (* one rewrite (possibly conditional, ordered) EXOR exn EXOR go into subterms *)
    1.61 +and rew_sub thy i bdv tless rls put_asm lrd r t = 
    1.62 +  (let
    1.63 +    val (lhs, rhs) = (HOLogic.dest_eq o HOLogic.dest_Trueprop o Logic.strip_imp_concl) r
    1.64 +    (*?alternative Unify.matchers:
    1.65 +      http://isabelle.in.tum.de/repos/isabelle/file/Isabelle2017/src/Pure/more_unify.ML*)
    1.66 +    val r' = Envir.subst_term (Pattern.match thy (lhs, t) (Vartab.empty, Vartab.empty)) r
    1.67 +    val p' = map HOLogic.dest_Trueprop ((fst o Logic.strip_prems) (Logic.count_prems r', [], r'))
    1.68 +    val t' = (snd o HOLogic.dest_eq o HOLogic.dest_Trueprop o Logic.strip_imp_concl) r'
    1.69 +    val _ = if ! Celem.trace_rewrite andalso i < ! Celem.depth andalso p' <> []
    1.70 +	    then tracing (idt "#" (i + 1) ^ " eval asms: " ^ UnparseC.t2str thy r') else ()
    1.71 +    val (t'', p'') =                                                     (*conditional rewriting*)
    1.72 +      let
    1.73 +        val (simpl_p', nofalse) = eval__true thy (i + 1) p' bdv rls 	     
    1.74 +	    in
    1.75 +	      if nofalse
    1.76 +        then
    1.77 +          (if ! Celem.trace_rewrite andalso i < ! Celem.depth andalso p' <> []
    1.78 +          then tracing (idt "#" (i + 1) ^ " asms accepted: " ^ UnparseC.ts2str thy p' ^
    1.79 +  	        "   stored: " ^ UnparseC.ts2str thy simpl_p')
    1.80 +  	      else();
    1.81 +          (t',simpl_p'))                                               (* uncond.rew. from above*)
    1.82 +        else 
    1.83 +          (if ! Celem.trace_rewrite andalso i < ! Celem.depth 
    1.84 +          then tracing (idt "#" (i + 1) ^ " asms false: " ^ UnparseC.ts2str thy p')
    1.85 +          else();
    1.86 +          raise STOP_REW_SUB (* don't go into subterms of cond *))
    1.87 +	    end
    1.88 +    in
    1.89 +      if TermC.perm lhs rhs andalso not (tless bdv (t', t))                        (*ordered rewriting*)
    1.90 +      then (if ! Celem.trace_rewrite andalso i < ! Celem.depth 
    1.91 +  	    then tracing (idt"#"i ^ " not: \"" ^ UnparseC.t2str thy t ^ "\" > \"" ^ UnparseC.t2str thy t' ^ "\"")
    1.92 +  	    else (); 
    1.93 +  	    raise NO_REWRITE)
    1.94 +  	  else (t'', p'', [], true)
    1.95 +    end
    1.96 +    ) handle _ (*TODO Pattern.MATCH when tests are ready: ERROR 364ce4699452 *) => 
    1.97 +      (case t of
    1.98 +        Const(s,T) => (Const(s,T),[],lrd,false)
    1.99 +      | Free(s,T) => (Free(s,T),[],lrd,false)
   1.100 +      | Var(n,T) => (Var(n,T),[],lrd,false)
   1.101 +      | Bound i => (Bound i,[],lrd,false)
   1.102 +      | Abs(s,T,body) => 
   1.103 +        let val (t', asms, _ (*lrd*), rew) =  rew_sub thy i bdv tless rls put_asm (lrd @ [TermC.D]) r body
   1.104 +    	   in (Abs(s, T, t'), asms, [], rew) end
   1.105 +      | t1 $ t2 => 
   1.106 +    	   let val (t2', asm2, lrd, rew2) = rew_sub thy i bdv tless rls put_asm (lrd @ [TermC.R]) r t2
   1.107 +    	   in
   1.108 +    	    if rew2 then (t1 $ t2', asm2, lrd, true)
   1.109 +    	    else
   1.110 +    	      let val (t1', asm1, lrd, rew1) = rew_sub thy i bdv tless rls put_asm (lrd @ [TermC.L]) r t1
   1.111 +    	      in if rew1 then (t1' $ t2, asm1, lrd, true) else (t1 $ t2,[], lrd, false) end
   1.112 +  end)
   1.113 +and eval__true thy i asms bdv rls =         (* simplify asumptions until one evaluates to false *)
   1.114 +  if asms = [@{term True}] orelse asms = [] then ([], true)
   1.115 +  else (* this allows to check Rrls with prepat = ([@{term True}], pat) *)
   1.116 +    if asms = [@{term False}] then ([], false)
   1.117 +    else
   1.118 +      let                            
   1.119 +        fun chk indets [] = (indets, true) (*return asms<>True until false*)
   1.120 +          | chk indets (a :: asms) =
   1.121 +            (case rewrite__set_ thy (i + 1) false bdv rls a of
   1.122 +              NONE => (chk (indets @ [a]) asms)
   1.123 +            | SOME (t, a') =>
   1.124 +              if t = @{term True} then (chk (indets @ a') asms) 
   1.125 +              else if t = @{term False} then ([], false)
   1.126 +            (*asm false .. thm not applied ^^^; continue until False vvv*)
   1.127 +            else chk (indets @ [t] @ a') asms);
   1.128 +      in chk [] asms end
   1.129 +and rewrite__set_ thy _ __ Rule_Set.Empty t =                             (* rewrite with a rule set *)
   1.130 +    error ("rewrite__set_ called with 'Erls' for '" ^ UnparseC.t2str thy t ^ "'")
   1.131 +  | rewrite__set_ thy i _ _ (rrls as Rule_Set.Rrls _) t =      (* rewrite with a 'reverse rule set' *)
   1.132 +    let
   1.133 +      val _= trace i (" rls: " ^ Rule_Set.rls2str rrls ^ " on: " ^ UnparseC.t2str thy t)
   1.134 +	    val (t', asm, rew) = app_rev thy (i + 1) rrls t                   
   1.135 +    in if rew then SOME (t', distinct asm) else NONE end
   1.136 +  | rewrite__set_ thy i put_asm bdv rls ct =          (* Rls, Seq containing Thms or Num_Calc, Cal1 *)
   1.137 +    let
   1.138 +      (* attention with cp to test/..: unbound thy, i, bdv, rls; TODO1803? pull out to rewrite__*)
   1.139 +      datatype switch = Appl | Noap;
   1.140 +      fun rew_once _ asm ct Noap [] = (ct, asm)         (* ?TODO unify with Prog_Expr.rew_once? *)
   1.141 +        | rew_once ruls asm ct Appl [] = 
   1.142 +          (case rls of Rule_Def.Repeat _ => rew_once ruls asm ct Noap ruls
   1.143 +          | Rule_Set.Seqence _ => (ct, asm)
   1.144 +          | rls => raise ERROR ("rew_once not appl. to \"" ^ Rule_Set.rls2str rls ^ "\""))
   1.145 +        | rew_once ruls asm ct apno (rul :: thms) =
   1.146 +          case rul of
   1.147 +            Rule.Thm (thmid, thm) =>
   1.148 +              (trace1 i (" try thm: \"" ^ thmid ^ "\"");
   1.149 +              case rewrite__ thy (i + 1) bdv ((snd o #rew_ord o Rule_Set.rep) rls)
   1.150 +                  ((#erls o Rule_Set.rep) rls) put_asm thm ct of
   1.151 +                NONE => rew_once ruls asm ct apno thms
   1.152 +              | SOME (ct', asm') => 
   1.153 +                (trace1 i (" rewrites to: \"" ^ UnparseC.t2str thy ct' ^ "\"");
   1.154 +                rew_once ruls (union (op =) asm asm') ct' Appl (rul :: thms)))
   1.155 +                (* once again try the same rule, e.g. associativity against "()"*)
   1.156 +          | Rule.Num_Calc (cc as (op_, _)) => 
   1.157 +            let val _= trace1 i (" try calc: \"" ^ op_ ^ "\"")
   1.158 +              val ct = TermC.uminus_to_string ct (*WN190312: superfluous?*)
   1.159 +            in case Num_Calc.adhoc_thm thy cc ct of
   1.160 +                NONE => rew_once ruls asm ct apno thms
   1.161 +              | SOME (_, thm') => 
   1.162 +                let 
   1.163 +                  val pairopt = rewrite__ thy (i + 1) bdv ((snd o #rew_ord o Rule_Set.rep) rls)
   1.164 +                    ((#erls o Rule_Set.rep) rls) put_asm thm' ct;
   1.165 +                  val _ = if pairopt <> NONE then () else error ("rewrite_set_, rewrite_ \"" ^ 
   1.166 +                    ThmC_Def.string_of_thmI thm' ^ "\" " ^ UnparseC.t2str thy ct ^ " = NONE")
   1.167 +                  val _ = trace1 i (" calc. to: " ^ UnparseC.t2str thy ((fst o the) pairopt))
   1.168 +                in rew_once ruls asm ((fst o the) pairopt) Appl (rul :: thms) end
   1.169 +            end
   1.170 +          | Rule.Cal1 (cc as (op_, _)) => 
   1.171 +            let val _= trace1 i (" try cal1: " ^ op_ ^ "'");
   1.172 +              val ct = TermC.uminus_to_string ct
   1.173 +            in case Num_Calc.adhoc_thm1_ thy cc ct of
   1.174 +                NONE => (ct, asm)
   1.175 +              | SOME (_, thm') =>
   1.176 +                let 
   1.177 +                  val pairopt = rewrite__ thy (i + 1) bdv ((snd o #rew_ord o Rule_Set.rep) rls)
   1.178 +                    ((#erls o Rule_Set.rep) rls) put_asm thm' ct;
   1.179 +                  val _ = if pairopt <> NONE then () else error ("rewrite_set_, rewrite_ \"" ^
   1.180 +                     ThmC_Def.string_of_thmI thm' ^ "\" " ^ UnparseC.t2str thy ct ^ " = NONE")
   1.181 +                  val _ = trace1 i (" cal1. to: " ^ UnparseC.t2str thy ((fst o the) pairopt))
   1.182 +                in the pairopt end
   1.183 +            end
   1.184 +          | Rule.Rls_ rls' => 
   1.185 +            (case rewrite__set_ thy (i + 1) put_asm bdv rls' ct of
   1.186 +              SOME (t', asm') => rew_once ruls (union (op =) asm asm') t' Appl thms
   1.187 +            | NONE => rew_once ruls asm ct apno thms)
   1.188 +          | r => raise ERROR ("rew_once not appl. to \"" ^ Rule.rule2str r ^ "\"");
   1.189 +      val ruls = (#rules o Rule_Set.rep) rls;
   1.190 +      val _ = trace i (" rls: " ^ Rule_Set.rls2str rls ^ " on: " ^ UnparseC.t2str thy ct)
   1.191 +      val (ct', asm') = rew_once ruls [] ct Noap ruls;
   1.192 +	  in if ct = ct' then NONE else SOME (ct', distinct asm') end
   1.193 +(*-------------------------------------------------------------*)
   1.194 +and app_rev thy i rrls t =            (* apply an Rrls; if not applicable proceed with subterms *)
   1.195 +  let (* check a (precond, pattern) of a rev-set; stops with 1st true *)
   1.196 +    fun chk_prepat _ _ [] _ = true
   1.197 +      | chk_prepat thy erls prepat t =
   1.198 +        let
   1.199 +          fun chk (pres, pat) =
   1.200 +            (let 
   1.201 +              val subst: Type.tyenv * Envir.tenv =
   1.202 +                Pattern.match thy (pat, t) (Vartab.empty, Vartab.empty)
   1.203 +             in
   1.204 +              snd (eval__true thy (i + 1) (map (Envir.subst_term subst) pres) [] erls)
   1.205 +             end) handle _ (*TODO Pattern.MATCH*) => false
   1.206 +           fun scan_ _ [] = false
   1.207 +             | scan_ f (pp :: pps) =
   1.208 +               if f pp then true else scan_ f pps;
   1.209 +        in scan_ chk prepat end;
   1.210 +    (* apply the normal_form of a rev-set *)
   1.211 +    fun app_rev' thy (Rule_Set.Rrls {erls, prepat, scr = Rule.Rfuns {normal_form, ...}, ...}) t =
   1.212 +      if chk_prepat thy erls prepat t then normal_form t else NONE
   1.213 +      | app_rev' _ r _ = raise ERROR ("app_rev' not appl. to \"" ^ Rule_Set.rls2str r ^ "\"");
   1.214 +    val opt = app_rev' thy rrls t
   1.215 +  in
   1.216 +    case opt of
   1.217 +      SOME (t', asm) => (t', asm, true)
   1.218 +    | NONE => app_sub thy i rrls t
   1.219 +  end
   1.220 +and app_sub thy i rrls t =                                         (* apply an Rrls to subterms *)
   1.221 +  case t of
   1.222 +    Const (s, T) => (Const(s, T), [], false)
   1.223 +  | Free (s, T) => (Free(s, T), [], false)
   1.224 +  | Var (n, T) => (Var(n, T), [], false)
   1.225 +  | Bound i => (Bound i, [], false)
   1.226 +  | Abs (s, T, body) => 
   1.227 +	  let val (t', asm, rew) = app_rev thy i rrls body
   1.228 +	  in (Abs(s, T, t'), asm, rew) end
   1.229 +  | t1 $ t2 => 
   1.230 +    let val (t2', asm2, rew2) = app_rev thy i rrls t2
   1.231 +    in
   1.232 +      if rew2 then (t1 $ t2', asm2, true)
   1.233 +      else
   1.234 +        let val (t1', asm1, rew1) = app_rev thy i rrls t1
   1.235 +        in if rew1 then (t1' $ t2, asm1, true)
   1.236 +           else (t1 $ t2, [], false)
   1.237 +        end
   1.238 +    end;
   1.239 +
   1.240 +(* rewriting without argument [] for rew_ord;  WN110603: shouldnt asm<>[] lead to false? *)
   1.241 +fun eval_true thy terms rls = (snd o (eval__true thy 1 terms [])) rls;
   1.242 +
   1.243 +(* rewriting without internal argument [] *)
   1.244 +fun rewrite_ thy rew_ord erls bool thm term = rewrite__ thy 1 [] rew_ord erls bool thm term;
   1.245 +fun rewrite_set_ thy bool rls term = rewrite__set_ thy 1 bool [] rls term;
   1.246 +
   1.247 +(* variants of rewrite; TODO del. put_asm *)
   1.248 +fun rewrite_inst_  thy rew_ord rls put_asm subst thm ct =
   1.249 +  rewrite__ thy 1 subst rew_ord rls put_asm thm ct;
   1.250 +fun rewrite_set_inst_ thy put_asm subst rls ct = rewrite__set_ thy 1 put_asm subst rls ct;
   1.251 +
   1.252 +(* given a list of equalities (lhs = rhs) and a term, 
   1.253 +   replace all occurrences of lhs in the term with rhs;
   1.254 +   thus the order or equalities matters: put variables in lhs first. *)
   1.255 +fun rewrite_terms_ thy ord erls equs t =
   1.256 +  let
   1.257 +	  fun rew_ (t', asm') [] _ = (t', asm')
   1.258 +	    | rew_ (t', asm') (rules as r::rs) t =
   1.259 +	        let
   1.260 +	          val (t'', asm'', _(*lrd*), rew) = rew_sub thy 1 [] ord erls false [] (HOLogic.Trueprop $ r) t
   1.261 +	        in 
   1.262 +	          if rew 
   1.263 +	          then rew_ (t'', asm' @ asm'') rules t''
   1.264 +	          else rew_ (t', asm') rs t'
   1.265 +	        end
   1.266 +	  val (t'', asm'') = rew_ (TermC.empty, []) equs t
   1.267 +    in if t'' = TermC.empty then NONE else SOME (t'', asm'')
   1.268 +    end;
   1.269 +
   1.270 +(* search ct for adjacent numerals and calculate them by operator isa_fn *)
   1.271 +fun calculate_ thy isa_fn ct =
   1.272 +  let val ct = TermC.uminus_to_string ct
   1.273 +    in case Num_Calc.adhoc_thm thy isa_fn ct of
   1.274 +	   NONE => NONE
   1.275 +	 | SOME (thmID, thm) =>
   1.276 +	   (let val rew = case rewrite_ thy Rewrite_Ord.dummy_ord Rule_Set.empty false thm ct of
   1.277 +         SOME (rew, _) => rew
   1.278 +       | NONE => raise ERROR ""
   1.279 +     in SOME (rew, (thmID, thm)) end)
   1.280 +	   handle _ (*TODO Pattern.MATCH ?del?*)=> error ("calculate_: " ^ thmID ^ " does not rewrite")
   1.281 +  end;
   1.282 +
   1.283 +(* Thm.make_thm added to Pure/thm.ML *)
   1.284 +fun mk_thm thy str = 
   1.285 +  let
   1.286 +    val t = (Thm.term_of o the o (TermC.parse thy)) str
   1.287 +    val t' = case t of
   1.288 +        Const ("Pure.imp", _) $ _ $ _ => t
   1.289 +      | _ => HOLogic.Trueprop $ t
   1.290 +  in Thm.make_thm (Thm.global_cterm_of thy t') end;
   1.291 +
   1.292 +(*/------- to ThmC_Def -------\*)
   1.293 +(* 
   1.294 +  "metaview" as seen from programs and from user input;
   1.295 +  both are parsed as terms by the function package.
   1.296 +*)
   1.297 +fun convert_metaview_to_thmid thy thmid =
   1.298 +  let val thmid' = case thmid of
   1.299 +      "add_commute" => "add.commute"
   1.300 +    | "mult_commute" => "mult.commute"
   1.301 +    | "add_left_commute" => "add.left_commute"
   1.302 +    | "mult_left_commute" => "mult.left_commute"
   1.303 +    | "add_assoc" => "add.assoc"
   1.304 +    | "mult_assoc" => "mult.assoc"
   1.305 +    | _ => thmid
   1.306 +  in (Global_Theory.get_thm thy) thmid' end;
   1.307 +
   1.308 +(* get the theorem associated with the xstring-identifier;
   1.309 +   if the identifier starts with "sym_" then swap lhs = rhs around =
   1.310 +   (ATTENTION: "RS sym" attaches a [.] -- remove it with ThmC_Def.string_of_thmI);
   1.311 +   identifiers starting with "#" come from Num_Calc and
   1.312 +   get a hand-made theorem (containing numerals only) *)
   1.313 +fun assoc_thm'' thy thmid =
   1.314 +  case Symbol.explode thmid of
   1.315 +    "s"::"y"::"m"::"_"::"#"::_ => error ("assoc_thm'' not impl.for " ^ thmid)
   1.316 +  | "s"::"y"::"m"::"_"::id => ((TermC.num_str o (Global_Theory.get_thm thy)) (implode id)) RS sym
   1.317 +  | "#"::_ => error ("assoc_thm'' not impl.for " ^ thmid)
   1.318 +  | _ => thmid |> convert_metaview_to_thmid thy |> TermC.num_str
   1.319 +fun assoc_thm' thy (thmid, ct') =
   1.320 +  (case Symbol.explode thmid of
   1.321 +    "s"::"y"::"m"::"_"::id => 
   1.322 +      if hd id = "#" 
   1.323 +      then mk_thm thy ct'
   1.324 +      else ((TermC.num_str o (Global_Theory.get_thm thy)) (implode id)) RS sym
   1.325 +  | id =>
   1.326 +    if hd id = "#" 
   1.327 +    then mk_thm thy ct'
   1.328 +    else thmid |> convert_metaview_to_thmid thy |> TermC.num_str
   1.329 +  ) handle _ (*TODO: find exn behind ERROR: Undefined fact: "add_commute"*) => 
   1.330 +    raise ERROR
   1.331 +      ("assoc_thm': \"" ^ thmid ^ "\" not in \"" ^ ThyC.theory2domID thy ^ "\" (and parents)")
   1.332 +(*\------- to ThmC_Def -------/*)
   1.333 +
   1.334 +
   1.335 +fun eval_prog_expr thy srls t =
   1.336 +  let val rew = rewrite_set_ thy false srls t;
   1.337 +  in case rew of SOME (res,_) => res | NONE => t end;
   1.338 +
   1.339 +fun eval_true_ _ _ (Const ("HOL.True",_)) = true
   1.340 +  | eval_true_ thy rls t =
   1.341 +    case rewrite_set_ thy false rls t of
   1.342 +	   SOME (Const ("HOL.True",_),_) => true
   1.343 +	 | _ => false;
   1.344 +
   1.345 +end
   1.346 \ No newline at end of file