src/Tools/isac/Scripts/calculate.sml
branchisac-update-Isa09-2
changeset 37947 22235e4dbe5f
parent 37946 a28b5fc129b7
child 37948 ed85f172569c
     1.1 --- a/src/Tools/isac/Scripts/calculate.sml	Wed Aug 25 15:15:01 2010 +0200
     1.2 +++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.3 @@ -1,408 +0,0 @@
     1.4 -(* calculate values for function constants
     1.5 -   (c) Walther Neuper 000106
     1.6 -
     1.7 -use"Scripts/calculate.sml";
     1.8 -*)
     1.9 -
    1.10 -
    1.11 -(* dirty type-conversion 30.1.00 for "fixed_values [R=R]" *)
    1.12 -
    1.13 -val aT = Type ("'a", []);
    1.14 -(* isas types for Free, parseold: (1) "R=R" or (2) "R=(R::real)": 
    1.15 -(1)
    1.16 -> val (TFree(ss2,TT2)) = T2;
    1.17 -val ss2 = "'a" : string
    1.18 -val TT2 = ["term"] : sort
    1.19 -(2)
    1.20 -> val (Type(ss2',TT2')) = T2';
    1.21 -val ss2' = "RealDef.real" : string
    1.22 -val TT2' = [] : typ list
    1.23 -(3)
    1.24 -val realType = TFree ("RealDef.real", HOLogic.termS);
    1.25 -is different internally, too;
    1.26 -
    1.27 -(1) .. (3) are displayed equally !!!
    1.28 -*)
    1.29 -
    1.30 -
    1.31 -
    1.32 -(* 30.1.00: generating special terms for ME:
    1.33 -   (1) binary numerals reconverted to Free ("#num",...) 
    1.34 -       by libarary_G.num_str: called from parse (below) and 
    1.35 -       interface_ME_ISA for all thms used
    1.36 -       (compare HOLogic.dest_binum)
    1.37 -   (2) 'a types converted to RealDef.real by typ_a2real
    1.38 -       in parse below
    1.39 -   (3) binary operators fixed to type real in RatArith.thy
    1.40 -       (trick by Markus Wenzel)
    1.41 -*)
    1.42 -
    1.43 -
    1.44 -
    1.45 -
    1.46 -(** calculate numerals **)
    1.47 -
    1.48 -(*27.3.00: problems with patterns below:
    1.49 -"Vars (a // #2 = r * xxxxx b)" doesn't work, but 
    1.50 -"Vars (a // #2 = r * sqrt b)" works
    1.51 -*)
    1.52 -
    1.53 -fun popt2str (SOME (str, term)) = "SOME "^term2str term
    1.54 -  | popt2str NONE = "NONE";
    1.55 -
    1.56 -(* scan a term for applying eval_fn ef 
    1.57 -args
    1.58 -  thy:
    1.59 -  op_: operator (as string) selecting the root of the pair
    1.60 -  ef : fn : (string -> term -> theory -> (string * term) option)
    1.61 -             ^^^^^^... for creating the string for the resulting theorem
    1.62 -  t  : term to be scanned
    1.63 -result:
    1.64 -  (string * term) option: found by the eval_* -function of type
    1.65 -       fn : string -> string -> term -> theory -> (string * term) option
    1.66 -            ^^^^^^... the selecting operator op_ (variable for eval_binop)
    1.67 -*)
    1.68 -fun get_pair thy op_ (ef:string -> term -> theory -> (string * term) option) 
    1.69 -    (t as (Const(op0,t0) $ arg)) =                      (* unary fns *)
    1.70 -(* val (thy, op_, (ef),    (t as (Const(op0,t0) $ arg))) = 
    1.71 -       (thy, op_, eval_fn, ct);
    1.72 -   *)
    1.73 -    if op_ = op0 then 
    1.74 -	let val popt = ef op_ t thy
    1.75 -	in case popt of
    1.76 -	       SOME _ => popt
    1.77 -	     | NONE => get_pair thy op_ ef arg end
    1.78 -    else get_pair thy op_ ef arg
    1.79 - 
    1.80 -  | get_pair thy "Atools.ident" ef (t as (Const("Atools.ident",t0) $ _ $ _ )) =
    1.81 -(* val (thy, "Atools.ident", ef,      t as (Const(op0,_) $ t1 $ t2)) =
    1.82 -       (thy, op_,            eval_fn, ct);
    1.83 -   *)
    1.84 -    ef "Atools.ident" t thy                                 (* not nested *)
    1.85 -
    1.86 -  | get_pair thy op_ ef (t as (Const(op0,_) $ t1 $ t2)) =  (* binary funs*)
    1.87 -(* val (thy, op_, ef,      (t as (Const(op0,_) $ t1 $ t2))) = 
    1.88 -       (thy, op_, eval_fn, ct);
    1.89 -   *)
    1.90 -    ((*writeln("1.. get_pair: binop = "^op_);*)
    1.91 -     if op_ = op0 then 
    1.92 -	 let val popt = ef op_ t thy
    1.93 -	 (*val _ = writeln("2.. get_pair: "^term2str t^" -> "^popt2str popt)*)
    1.94 -	 in case popt of 
    1.95 -		SOME (id,_) => popt
    1.96 -	      | NONE => 
    1.97 -		let val popt = get_pair thy op_ ef t1
    1.98 -		    (*val _ = writeln("3.. get_pair: "^term2str t1^
    1.99 -				    " -> "^popt2str popt)*)
   1.100 -		in case popt of 
   1.101 -		       SOME (id,_) => popt
   1.102 -		     | NONE => get_pair thy op_ ef t2
   1.103 -		end
   1.104 -	 end
   1.105 -     else (*search subterms*)
   1.106 -	 let val popt = get_pair thy op_ ef t1
   1.107 -	 (*val _ = writeln("4.. get_pair: "^term2str t^" -> "^popt2str popt)*)
   1.108 -	 in case popt of 
   1.109 -		SOME (id,_) => popt
   1.110 -	      | NONE => get_pair thy op_ ef t2
   1.111 -	 end)
   1.112 -  | get_pair thy op_ ef (t as (Const(op0,_) $ t1 $ t2 $ t3)) =(* trinary funs*)
   1.113 -    ((*writeln("### get_pair 4a: t= "^term2str t);
   1.114 -     writeln("### get_pair 4a: op_= "^op_);
   1.115 -     writeln("### get_pair 4a: op0= "^op0);*)
   1.116 -     if op_ = op0 then 
   1.117 -	case ef op_ t thy of
   1.118 -	    SOME tt => SOME tt
   1.119 -	  | NONE => (case get_pair thy op_ ef t2 of
   1.120 -			 SOME tt => SOME tt
   1.121 -		       | NONE => get_pair thy op_ ef t3)
   1.122 -    else (case get_pair thy op_ ef t1 of
   1.123 -	     SOME tt => SOME tt
   1.124 -	   | NONE => (case get_pair thy op_ ef t2 of
   1.125 -			  SOME tt => SOME tt
   1.126 -			| NONE => get_pair thy op_ ef t3)))
   1.127 -  | get_pair thy op_ ef (Const _) = NONE
   1.128 -  | get_pair thy op_ ef (Free _) = NONE
   1.129 -  | get_pair thy op_ ef (Var _) = NONE
   1.130 -  | get_pair thy op_ ef (Bound _) = NONE
   1.131 -  | get_pair thy op_ ef (Abs(a,T,body)) = get_pair thy op_ ef body
   1.132 -  | get_pair thy op_ ef (t1$t2) = 
   1.133 -    let(*val _= writeln("5.. get_pair t1 $ t2: "^term2str t1^" 
   1.134 -						   $ "^term2str t2)*)
   1.135 -	val popt = get_pair thy op_ ef t1
   1.136 -    in case popt of 
   1.137 -	   SOME _ => popt
   1.138 -	 | NONE => ((*writeln"### get_pair: t1 $ t2 -> NONE";*)
   1.139 -		    get_pair thy op_ ef t2) 
   1.140 -    end;
   1.141 - (*
   1.142 ->  val t = (term_of o the o (parse thy)) "#3 + #4";
   1.143 ->  val eval_fn = the (assoc (!eval_list, "op +"));
   1.144 ->  val (SOME (id,t')) = get_pair thy "op +" eval_fn t;
   1.145 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.146 ->  atomty t';
   1.147 -> 
   1.148 ->  val t = (term_of o the o (parse thy)) "(a + #3) + #4";
   1.149 ->  val (SOME (id,t')) = get_pair thy "op +" eval_fn t;
   1.150 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.151 -> 
   1.152 ->  val t = (term_of o the o (parse thy)) "#3 + (#4 + (a::real))";
   1.153 ->  val (SOME (id,t')) = get_pair thy "op +" eval_fn t;
   1.154 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.155 -> 
   1.156 ->  val t = (term_of o the o (parse thy)) "x = #5 * (#3 + (#4 + a))";
   1.157 ->  atomty t;
   1.158 ->  val (SOME (id,t')) = get_pair thy "op +" eval_fn t;
   1.159 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.160 ->  val it = "#3 + (#4 + a) = #7 + a" : string
   1.161 ->
   1.162 ->
   1.163 ->  val t = (term_of o the o (parse thy)) "#-4//#-2";
   1.164 ->  val eval_fn = the (assoc (!eval_list, "cancel"));
   1.165 ->  val (SOME (id,t')) = get_pair thy "cancel" eval_fn t;
   1.166 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.167 -> 
   1.168 ->  val t = (term_of o the o (parse thy)) "#2^^^#3";
   1.169 ->  eval_binop "xxx" "pow" t thy;
   1.170 ->  val eval_fn = (eval_binop "xxx")
   1.171 ->		 : string -> term -> theory -> (string * term) option;
   1.172 ->  val SOME (id,t') = get_pair thy "pow" eval_fn t;
   1.173 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.174 ->  val eval_fn = the (assoc (!eval_list, "pow"));
   1.175 ->  val (SOME (id,t')) = get_pair thy "pow" eval_fn t;
   1.176 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.177 -> 
   1.178 ->  val t = (term_of o the o (parse thy)) "x = #0 + #-1 * #-4";
   1.179 ->  val eval_fn = the (assoc (!eval_list, "op *"));
   1.180 ->  val (SOME (id,t')) = get_pair thy "op *" eval_fn t;
   1.181 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.182 -> 
   1.183 ->  val t = (term_of o the o (parse thy)) "#0 < #4";
   1.184 ->  val eval_fn = the (assoc (!eval_list, "op <"));
   1.185 ->  val (SOME (id,t')) = get_pair thy "op <" eval_fn t;
   1.186 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.187 ->  val t = (term_of o the o (parse thy)) "#0 < #-4";
   1.188 ->  val (SOME (id,t')) = get_pair thy "op <" eval_fn t;
   1.189 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.190 -> 
   1.191 ->  val t = (term_of o the o (parse thy)) "#3 is_const";
   1.192 ->  val eval_fn = the (assoc (!eval_list, "is'_const"));
   1.193 ->  val (SOME (id,t')) = get_pair thy "is'_const" eval_fn t;
   1.194 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.195 ->  val t = (term_of o the o (parse thy)) "a is_const";
   1.196 ->  val (SOME (id,t')) = get_pair thy "is'_const" eval_fn t;
   1.197 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.198 -> 
   1.199 ->  val t = (term_of o the o (parse thy)) "#6//(#8::real)";
   1.200 ->  val eval_fn = the (assoc (!eval_list, "cancel"));
   1.201 ->  val (SOME (id,t')) = get_pair thy "cancel" eval_fn t;
   1.202 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.203 -> 
   1.204 ->  val t = (term_of o the o (parse thy)) "sqrt #12";
   1.205 ->  val eval_fn = the (assoc (!eval_list, "SqRoot.sqrt"));
   1.206 ->  val (SOME (id,t')) = get_pair thy "SqRoot.sqrt" eval_fn t;
   1.207 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.208 ->  val it = "sqrt #12 = #2 * sqrt #3 " : string
   1.209 ->
   1.210 ->  val t = (term_of o the o (parse thy)) "sqrt #9";
   1.211 ->  val (SOME (id,t')) = get_pair thy "SqRoot.sqrt" eval_fn t;
   1.212 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.213 ->
   1.214 ->  val t = (term_of o the o (parse thy)) "Nth #2 [#11,#22,#33]";
   1.215 ->  val eval_fn = the (assoc (!eval_list, "Tools.Nth"));
   1.216 ->  val (SOME (id,t')) = get_pair thy "Tools.Nth" eval_fn t;
   1.217 ->  Syntax.string_of_term (thy2ctxt thy) t';
   1.218 -*)
   1.219 -
   1.220 -(* val ((op_, eval_fn),ct)=(cc,pre);
   1.221 -   (get_calculation_ Isac.thy (op_, eval_fn) ct) handle e => print_exn e;
   1.222 -   parse thy ""
   1.223 -   *)
   1.224 -(*.get a thm from an op_ somewhere in the term;
   1.225 -   apply ONLY to (uminus_to_string term), uminus_to_string (- 4711) --> (-4711).*)
   1.226 -fun get_calculation_ thy (op_, eval_fn) ct =
   1.227 -(* val (thy, (op_, eval_fn),                           ct) = 
   1.228 -       (thy, (the (assoc(!calclist',"order_system"))), t);
   1.229 -   *)
   1.230 -  case get_pair thy op_ eval_fn ct of
   1.231 -	 NONE => ((*writeln("@@@ get_calculation: NONE, op_="^op_);
   1.232 -		  writeln("@@@ get_calculation: ct= ");atomty ct;*)
   1.233 -		  NONE)
   1.234 -       | SOME (thmid,t) =>
   1.235 -	   ((*writeln("@@@ get_calculation: NONE, op_="^op_);
   1.236 -	    writeln("@@@ get_calculation: ct= ");atomty ct;*)
   1.237 -	    SOME (thmid, (make_thm o (cterm_of thy)) t));
   1.238 -(*
   1.239 -> val ct = (the o (parse thy)) "#9 is_const";
   1.240 -> get_calculation_ thy ("is'_const",the (assoc(!eval_list,"is'_const"))) ct;
   1.241 -val it = SOME ("is_const9_","(is_const 9 ) = True  [(is_const 9 ) = True]")
   1.242 -
   1.243 -> val ct = (the o (parse thy)) "sqrt #9";
   1.244 -> get_calculation_ thy ("sqrt",the (assoc(!eval_list,"sqrt"))) ct;
   1.245 -val it = SOME ("sqrt_9_","sqrt 9  = 3  [sqrt 9  = 3]") : (string * thm) option
   1.246 -
   1.247 -> val ct = (the o (parse thy)) "#4<#4";
   1.248 -> get_calculation_ thy ("op <",the (assoc(!eval_list,"op <"))) ct;fun is_no str = (hd o explode) str = "#";
   1.249 -
   1.250 -val it = SOME ("less_5_4","(5 < 4) = False  [(5 < 4) = False]")
   1.251 -
   1.252 -> val ct = (the o (parse thy)) "a<#4";
   1.253 -> get_calculation_ thy ("op <",the (assoc(!eval_list,"op <"))) ct;
   1.254 -val it = NONE : (string * thm) option
   1.255 -
   1.256 -> val ct = (the o (parse thy)) "#5<=#4";
   1.257 -> get_calculation_ thy ("op <=",the (assoc(!eval_list,"op <="))) ct;
   1.258 -val it = SOME ("less_equal_5_4","(5 <= 4) = False  [(5 <= 4) = False]")
   1.259 -
   1.260 --------------------------------------------------------------------6.8.02:
   1.261 - val thy = SqRoot.thy;
   1.262 - val t = (term_of o the o (parse thy)) "1+2";
   1.263 - get_calculation_ thy (the(assoc(!calc_list,"PLUS"))) t;
   1.264 - val it = SOME ("add_3_4","3 + 4 = 7  [3 + 4 = 7]") : (string * thm) option
   1.265 --------------------------------------------------------------------6.8.02:
   1.266 - val t = (term_of o the o (parse thy)) "-1";
   1.267 - atomty t;
   1.268 - val t = (term_of o the o (parse thy)) "0";
   1.269 - atomty t;
   1.270 - val t = (term_of o the o (parse thy)) "1";
   1.271 - atomty t;
   1.272 - val t = (term_of o the o (parse thy)) "2";
   1.273 - atomty t;
   1.274 - val t = (term_of o the o (parse thy)) "999999999";
   1.275 - atomty t;
   1.276 --------------------------------------------------------------------6.8.02:
   1.277 -
   1.278 -> val ct = (the o (parse thy)) "a+#3+#4";
   1.279 -> get_calculation_ thy ("op +",the (assoc(!eval_list,"op +"))) ct;
   1.280 -val it = SOME ("add_3_4","a + 3 + 4 = a + 7  [a + 3 + 4 = a + 7]")
   1.281 - 
   1.282 -> val ct = (the o (parse thy)) "#3+(#4+a)";
   1.283 -> get_calculation_ thy ("op +",the (assoc(!eval_list,"op +"))) ct;
   1.284 -val it = SOME ("add_3_4","3 + (4 + a) = 7 + a  [3 + (4 + a) = 7 + a]")
   1.285 - 
   1.286 -> val ct = (the o (parse thy)) "a+(#3+#4)+#5";
   1.287 -> get_calculation_ thy ("op +",the (assoc(!eval_list,"op +"))) ct;
   1.288 -val it = SOME ("add_3_4","3 + 4 = 7  [3 + 4 = 7]") : (string * thm) option
   1.289 -
   1.290 -> val ct = (the o (parse thy)) "#3*(#4*a)";
   1.291 -> get_calculation_ thy ("op *",the (assoc(!eval_list,"op *"))) ct;
   1.292 -val it = SOME ("mult_3_4","3 * (4 * a) = 12 * a  [3 * (4 * a) = 12 * a]")
   1.293 -
   1.294 -> val ct = (the o (parse thy)) "#3 + #4^^^#2 + #5";
   1.295 -> get_calculation_ thy ("pow",the (assoc(!eval_list,"pow"))) ct;
   1.296 -val it = SOME ("4_(+2)","4 ^ 2 = 16  [4 ^ 2 = 16]") : (string * thm) option
   1.297 -
   1.298 -> val ct = (the o (parse thy)) "#-4//#-2";
   1.299 -> get_calculation_ thy ("cancel",the (assoc(!eval_list,"cancel"))) ct;
   1.300 -val it = SOME ("cancel_(-4)_(-2)","(-4) // (-2) = (+2)  [(-4) // (-2) = (+2)]")
   1.301 -
   1.302 -> val ct = (the o (parse thy)) "#6//#-8";
   1.303 -> get_calculation_ thy ("cancel",the (assoc(!eval_list,"cancel"))) ct;
   1.304 -val it = SOME ("cancel_6_(-8)","6 // (-8) = (-3) // 4  [6 // (-8) = (-3) // 4]")
   1.305 -
   1.306 -*) 
   1.307 -
   1.308 -
   1.309 -(*
   1.310 -> val ct = (the o (parse thy)) "a + 3*4";
   1.311 -> applicable "calculate" (Calc("op *", "mult_")) ct;
   1.312 -val it = SOME "3 * 4 = 12  [3 * 4 = 12]" : thm option
   1.313 -
   1.314 ---------------------------
   1.315 -> val ct = (the o (parse thy)) "3 =!= 3";
   1.316 -> val (thmid, thm) = the (get_calculation_ thy "Atools.ident" ct);
   1.317 -val thm = "(3 =!= 3) = True  [(3 =!= 3) = True]" : thm
   1.318 -
   1.319 -> val ct = (the o (parse thy)) "~ (3 =!= 3)";
   1.320 -> val (thmid, thm) = the (get_calculation_ thy "Atools.ident" ct);
   1.321 -val thm = "(3 =!= 3) = True  [(3 =!= 3) = True]" : thm
   1.322 -
   1.323 -> val ct = (the o (parse thy)) "3 =!= 4";
   1.324 -> val (thmid, thm) = the (get_calculation_ thy "Atools.ident" ct);
   1.325 -val thm = "(3 =!= 4) = False  [(3 =!= 4) = False]" : thm
   1.326 -
   1.327 -> val ct = (the o (parse thy)) "( 4 + (4 * x + x ^ 2) =!= (+0))";
   1.328 -> val (thmid, thm) = the (get_calculation_ thy "Atools.ident" ct);
   1.329 -  "(4 + (4 * x + x ^ 2) =!= (+0)) = False"
   1.330 -
   1.331 -> val ct = (the o (parse thy)) "~ ( 4 + (4 * x + x ^ 2) =!= (+0))";
   1.332 -> val (thmid, thm) = the (get_calculation_ thy "Atools.ident" ct);
   1.333 -  "(4 + (4 * x + x ^ 2) =!= (+0)) = False"
   1.334 -
   1.335 -> val ct = (the o (parse thy)) "~ ( 4 + (4 * x + x ^ 2) =!= (+0))";
   1.336 -> val rls = eval_rls;
   1.337 -> val (ct,_) = the (rewrite_set_ thy false rls ct);
   1.338 -val ct = "True" : cterm
   1.339 ---------------------------
   1.340 -*)
   1.341 -
   1.342 -
   1.343 -(*.get a thm applying an op_ to a term;
   1.344 -   apply ONLY to (numbers_to_string term), numbers_to_string (- 4711) --> (-4711).*)
   1.345 -(* val (thy, (op_, eval_fn), ct) = 
   1.346 -       (thy, ("Integrate.add'_new'_c", eval_add_new_c "add_new_c_"), term);
   1.347 -   *)
   1.348 -fun get_calculation1_ thy ((op_, eval_fn):cal) ct =
   1.349 -    case eval_fn op_ ct thy of
   1.350 -	NONE => NONE
   1.351 -      | SOME (thmid,t) =>
   1.352 -	SOME (thmid, (make_thm o (cterm_of thy)) t);
   1.353 -
   1.354 -
   1.355 -
   1.356 -
   1.357 -
   1.358 -(*.substitute bdv in an rls and leave Calc as they are.(*28.10.02*)
   1.359 -fun inst_thm' subs (Thm (id, thm)) = 
   1.360 -    Thm (id, (*read_instantiate throws: *** No such variable in term: ?bdv*)
   1.361 -	 (read_instantiate subs thm) handle _ => thm)
   1.362 -  | inst_thm' _ calc = calc; 
   1.363 -fun inst_thm' (subs as (bdv,_)::_) (Thm (id, thm)) = 
   1.364 -    Thm (id, (writeln("@@@ inst_thm': thm= "^(string_of_thmI thm));
   1.365 -	      if bdv mem (vars_str o #prop o rep_thm) thm
   1.366 -	     then (writeln("@@@ inst_thm': read_instantiate, thm="^((string_of_thmI thm)));
   1.367 -		   read_instantiate subs thm)
   1.368 -	     else (writeln("@@@ inst_thm': not mem.. "^bdv);
   1.369 -		   thm)))
   1.370 -  | inst_thm' _ calc = calc; 
   1.371 -
   1.372 -fun instantiate_rls subs 
   1.373 -  (Rls{preconds=preconds,rew_ord=rew_ord,erls=ev,srls=sr,calc=ca,
   1.374 -       asm_thm=at,rules=rules,scr=scr}:rls) =
   1.375 -  (Rls{preconds=preconds,rew_ord=rew_ord,erls=ev,srls=sr,calc=ca,
   1.376 -       asm_thm=at,scr=scr,
   1.377 -   rules = map (inst_thm' subs) rules}:rls);---------------------------*)
   1.378 -
   1.379 -
   1.380 -
   1.381 -(** rewriting: ordered, conditional **)
   1.382 -
   1.383 -fun mk_rule (prems,l,r) = 
   1.384 -    Trueprop $ (list_implies (prems, mk_equality (l,r)));
   1.385 -
   1.386 -(* 'norms' a rule, e.g.
   1.387 -(*1*) a = 1 ==> a*(b+c) = b+c 
   1.388 -                =>  a = 1 ==> a*(b+c) = b+c          no change
   1.389 -(*2*) t = t     =>  (t=t) = True                        !!
   1.390 -(*3*) [| k < l; m + l = k + n |] ==> m < n
   1.391 -	        =>  [| k<l; m+l=k+n |] ==> m < n = True !! *)
   1.392 -(* val it = fn : term -> term *)
   1.393 -fun norm rule =
   1.394 -  let
   1.395 -    val (prems,concl)=(map strip_trueprop(Logic.strip_imp_prems rule),
   1.396 -		       (strip_trueprop o  Logic.strip_imp_concl)rule)
   1.397 -  in if is_equality concl then 
   1.398 -      let val (l,r) = dest_equals' concl
   1.399 -      in if l = r then 
   1.400 -	 (*2*) mk_rule(prems,concl,true_as_term)
   1.401 -	 else (*1*) rule end
   1.402 -     else (*3*) mk_rule(prems,concl,true_as_term)
   1.403 -  end;
   1.404 -
   1.405 -
   1.406 -
   1.407 -
   1.408 -
   1.409 -
   1.410 -
   1.411 -