(* Title:  Test_Z_Transform

    Author: Jan Rocnik

    (c) copyright due to lincense terms.

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 *)

 theory Inverse_Z_Transform imports Isac begin

 section {*trials towards Z transform *}

 text{*===============================*}

 subsection {*terms*}

 ML {*

 @{term "1 < || z ||"};

 @{term "z / (z - 1)"};

 @{term "-u -n - 1"};

 @{term "-u [-n - 1]"}; (*[ ] denotes lists !!!*)

 @{term "z /(z - 1) = -u [-n - 1]"};Isac

 @{term "1 < || z || ==> z / (z - 1) = -u [-n - 1]"};

 term2str @{term "1 < || z || ==> z / (z - 1) = -u [-n - 1]"};

 *}

 ML {*

 (*alpha -->  "</alpha>" *)

 @{term "\<alpha> "};

 @{term "\<delta> "};

 @{term "\<phi> "};

 @{term "\<rho> "};

 term2str @{term "\<rho> "};

 *}

 subsection {*rules*}

 (*axiomatization "z / (z - 1) = -u [-n - 1]" Illegal variable name: "z / (z - 1) = -u [-n - 1]" *)

 (*definition     "z / (z - 1) = -u [-n - 1]" Bad head of lhs: existing constant "op /"*)

 axiomatization where 

   rule1: "1 = \<delta>[n]" and

   rule2: "|| z || > 1 ==> z / (z - 1) = u [n]" and

   rule3: "|| z || < 1 ==> z / (z - 1) = -u [-n - 1]" and 

   rule4: "|| z || > || \<alpha> || ==> z / (z - \<alpha>) = \<alpha>^^^n * u [n]" and

   rule5: "|| z || < || \<alpha> || ==> z / (z - \<alpha>) = -(\<alpha>^^^n) * u [-n - 1]" and

   rule6: "|| z || > 1 ==> z/(z - 1)^^^2 = n * u [n]"

 ML {*

 @{thm rule1};

 @{thm rule2};

 @{thm rule3};

 @{thm rule4};

 *}

 subsection {*apply rules*}

 ML {*

 val inverse_Z = append_rls "inverse_Z" e_rls

   [ Thm  ("rule3",num_str @{thm rule3}),

     Thm  ("rule4",num_str @{thm rule4}),

     Thm  ("rule1",num_str @{thm rule1})   

   ];

 val t = str2term "z / (z - 1) + z / (z - \<alpha>) + 1";

 val SOME (t', asm) = rewrite_set_ thy true inverse_Z t;

 term2str t' = "z / (z - ?\<delta> [?n]) + z / (z - \<alpha>) + ?\<delta> [?n]"; (*attention rule1 !!!*)

 *}

 ML {*

 val (thy, ro, er) = (@{theory}, tless_true, eval_rls);

 *}

 ML {*

 val SOME (t, asm1) = rewrite_ thy ro er true (num_str @{thm rule3}) t;

 term2str t = "- ?u [- ?n - 1] + z / (z - \<alpha>) + 1"; (*- real *)

 term2str t;

 *}

 ML {*

 val SOME (t, asm2) = rewrite_ thy ro er true (num_str @{thm rule4}) t;

 term2str t = "- ?u [- ?n - 1] + \<alpha> ^^^ ?n * ?u [?n] + 1"; (*- real *)

 term2str t;

 *}

 ML {*

 val SOME (t, asm3) = rewrite_ thy ro er true (num_str @{thm rule1}) t;

 term2str t = "- ?u [- ?n - 1] + \<alpha> ^^^ ?n * ?u [?n] + ?\<delta> [?n]"; (*- real *)

 term2str t;

 *}

 ML {*

 terms2str (asm1 @ asm2 @ asm3);

 *}

 section {*Prepare steps in CTP-based programming language*}

 text{*===================================================*}

 subsection {*prepare expression*}

 ML {*

 val ctxt = ProofContext.init_global @{theory};

 val ctxt = declare_constraints' [@{term "z::real"}] ctxt;

 val SOME fun1 = parseNEW ctxt "X z = 3 / (z - 1/4 + -1/8 * z ^^^ -1)"; term2str fun1;

 val SOME fun1' = parseNEW ctxt "X z = 3 / (z - 1/4 + -1/8 * (1/z))"; term2str fun1';

 *}

 axiomatization where

   ruleZY: "(X z = a / b) = (X' z = a / (z * b))"

 ML {*

 val (thy, ro, er) = (@{theory}, tless_true, eval_rls);

 val SOME (fun2, asm1) = rewrite_ thy ro er true  @{thm ruleZY} fun1; term2str fun2;

 val SOME (fun2', asm1) = rewrite_ thy ro er true  @{thm ruleZY} fun1'; term2str fun2';

 val SOME (fun3,_) = rewrite_set_ @{theory Isac} false norm_Rational fun2;

 term2str fun3; (*fails on x^^^(-1) TODO*)

 val SOME (fun3',_) = rewrite_set_ @{theory Isac} false norm_Rational fun2';

 term2str fun3'; (*OK*)

 val (_, expr) = HOLogic.dest_eq fun3'; term2str expr;

 *}

 subsection {*solve equation*}

 text {*this type of equation if too general for the present program*}

 ML {*

 "----------- Minisubplb/100-init-rootp (*OK*)bl.sml ---------------------";

 val denominator = parseNEW ctxt "z^^^2 - 1/4*z - 1/8 = 0";

 val fmz = ["equality (z^^^2 - 1/4*z - 1/8 = (0::real))", "solveFor z","solutions L"];

 val (dI',pI',mI') =("Isac", ["univariate","equation"], ["no_met"]);

 (*                           ^^^^^^^^^^^^^^^^^^^^^^ TODO: ISAC determines type of eq*)

 *}

 text {*Does the Equation Match the Specification ?*}

 ML {*

 match_pbl fmz (get_pbt ["univariate","equation"]);

 *}

 ML {*

 val denominator = parseNEW ctxt "-1/8 + -1/4*z + z^^^2 = 0";

 val fmz =                                            (*specification*)

   ["equality (-1/8 + (-1/4)*z + z^^^2 = (0::real))", (*equality*)

    "solveFor z",                                     (*bound variable*)

    "solutions L"];                                   (*identifier for solution*)

 (*liste der theoreme die zum lösen benötigt werden, aus isac, keine spezielle methode (no met)*)

 val (dI',pI',mI') =

   ("Isac", ["pqFormula","degree_2","polynomial","univariate","equation"], ["no_met"]);

 *}

 text {*Does the Other Equation Match the Specification ?*}

 ML {*

 match_pbl fmz (get_pbt ["pqFormula","degree_2","polynomial","univariate","equation"]);

 *}

 text {*Solve Equation Stepwise*}

 ML {*

 val (p,_,f,nxt,_,pt) = CalcTreeTEST [(fmz, (dI',pI',mI'))];

 val (p,_,f,nxt,_,pt) = me nxt p [] pt;

 val (p,_,f,nxt,_,pt) = me nxt p [] pt;

 val (p,_,f,nxt,_,pt) = me nxt p [] pt;

 val (p,_,f,nxt,_,pt) = me nxt p [] pt;

 val (p,_,f,nxt,_,pt) = me nxt p [] pt;

 val (p,_,f,nxt,_,pt) = me nxt p [] pt;

 val (p,_,f,nxt,_,pt) = me nxt p [] pt;

 val (p,_,f,nxt,_,pt) = me nxt p [] pt;

 val (p,_,f,nxt,_,pt) = me nxt p [] pt;

 val (p,_,f,nxt,_,pt) = me nxt p [] pt;

 val (p,_,f,nxt,_,pt) = me nxt p [] pt;         

 val (p,_,f,nxt,_,pt) = me nxt p [] pt; (*nxt =..,Check_elementwise "Assumptions")*)

 val (p,_,f,nxt,_,pt) = me nxt p [] pt;         

 val (p,_,f,nxt,_,pt) = me nxt p [] pt; f2str f;

 (*[z = 1 / 8 + sqrt (9 / 16) / 2, z = 1 / 8 + -1 * sqrt (9 / 16) / 2] TODO sqrt*)

 show_pt pt; 

 val SOME f = parseNEW ctxt "[z=1/2, z=-1/4]";

 *}

 subsection {*partial fraction decomposition*}

 subsubsection {*solution of the equation*}

 ML {*

 val SOME solutions = parseNEW ctxt "[z=1/2, z=-1/4]";

 term2str solutions;

 atomty solutions;

 *}

 subsubsection {*get solutions out of list*}

 text {*in isac's CTP-based programming language: let$ $s_1 = NTH 1$ solutions; $s_2 = NTH 2...$*}

 ML {*

 val Const ("List.list.Cons", _) $ s_1 $ (Const ("List.list.Cons", _) $

       s_2 $ Const ("List.list.Nil", _)) = solutions;

 term2str s_1;

 term2str s_2;

 *}

 ML {* (*Solutions as Denominator --> Denominator1 = z - Zeropoint1, Denominator2 = z-Zeropoint2,...*)

 val xx = HOLogic.dest_eq s_1;

 val s_1' = HOLogic.mk_binop "Groups.minus_class.minus" xx;

 val xx = HOLogic.dest_eq s_2;

 val s_2' = HOLogic.mk_binop "Groups.minus_class.minus" xx;

 term2str s_1';

 term2str s_2';

 *}

 subsubsection {*build expression*}

 text {*in isac's CTP-based programming language: let s_1 = Take numerator / (s_1 * s_2)*}

 ML {*

 (*The Main Denominator is the multiplikation of the partial fraction denominators*)

 val denominator' = HOLogic.mk_binop "Groups.times_class.times" (s_1', s_2') ;

 val SOME numerator = parseNEW ctxt "3::real";

 val expr' = HOLogic.mk_binop "Rings.inverse_class.divide" (numerator, denominator');

 term2str expr';

 *}

 subsubsection {*Ansatz - create partial fractions out of our expression*}

 axiomatization where

   ansatz2: "n / (a*b) = A/a + B/(b::real)" and

   multiply_eq2: "(n / (a*b) = A/a + B/b) = (a*b*(n  / (a*b)) = a*b*(A/a + B/b))"

 ML {*

 (*we use our ansatz2 to rewrite our expression and get an equilation with our expression on the left and the partial fractions of it on the right side*)

 val SOME (t1,_) = rewrite_ @{theory Isac} e_rew_ord e_rls false @{thm ansatz2} expr';

 term2str t1; atomty t1;

 val eq1 = HOLogic.mk_eq (expr', t1);

 term2str eq1;

 *}

 ML {*

 (*eliminate the demoninators by multiplying the left and the right side with the main denominator*)

 val SOME (eq2,_) = rewrite_ @{theory Isac} e_rew_ord e_rls false @{thm multiply_eq2} eq1;

 term2str eq2;

 *}

 ML {*

 (*simplificatoin*)

 val SOME (eq3,_) = rewrite_set_ @{theory Isac} false norm_Rational eq2;

 term2str eq3; (*?A ?B not simplified*)

 *}

 ML {*

 val SOME fract1 =

   parseNEW ctxt "(z - 1 / 2) * (z - -1 / 4) * (A / (z - 1 / 2) + B / (z - -1 / 4))"; (*A B !*)

 val SOME (fract2,_) = rewrite_set_ @{theory Isac} false norm_Rational fract1;

 term2str fract2 = "(A + -2 * B + 4 * A * z + 4 * B * z) / 4";

 (*term2str fract2 = "A * (1 / 4 + z) + B * (-1 / 2 + z)" would be more traditional*)

 *}

 ML {*

 val (numerator, denominator) = HOLogic.dest_eq eq3;

 val eq3' = HOLogic.mk_eq (numerator, fract1); (*A B !*)

 term2str eq3';

 (*MANDATORY: simplify (and remove denominator) otherwise 3 = 0*)

 val SOME (eq3'' ,_) = rewrite_set_ @{theory Isac} false norm_Rational eq3';

 term2str eq3'';

 *}

 subsubsection {*get first koeffizient*}

 ML {*

 (*substitude z with the first zeropoint to get A*)

 val SOME (eq4_1,_) = rewrite_terms_ @{theory Isac} e_rew_ord e_rls [s_1] eq3'';

 term2str eq4_1;

 val SOME (eq4_2,_) = rewrite_set_ @{theory Isac} false norm_Rational eq4_1;

 term2str eq4_2;

 val fmz = ["equality (3 = 3 * A / (4::real))", "solveFor A","solutions L"];

 val (dI',pI',mI') =("Isac", ["univariate","equation"], ["no_met"]);

 (*solve the simple linear equilation for A TODO: return eq, not list of eq*)

 val (p,_,fa,nxt,_,pt) = CalcTreeTEST [(fmz, (dI',pI',mI'))];

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fa,nxt,_,pt) = me nxt p [] pt; 

 f2str fa;

 *}

 subsubsection {*get second koeffizient*}

 ML {*

 (*substitude z with the second zeropoint to get B*)

 val SOME (eq4b_1,_) = rewrite_terms_ @{theory Isac} e_rew_ord e_rls [s_2] eq3'';

 term2str eq4b_1;

 val SOME (eq4b_2,_) = rewrite_set_ @{theory Isac} false norm_Rational eq4b_1;

 term2str eq4b_2;

 *}

 ML {*

 (*solve the simple linear equilation for B TODO: return eq, not list of eq*)

 val fmz = ["equality (3 = -3 * B / (4::real))", "solveFor B","solutions L"];

 val (dI',pI',mI') =("Isac", ["univariate","equation"], ["no_met"]);

 val (p,_,fb,nxt,_,pt) = CalcTreeTEST [(fmz, (dI',pI',mI'))];

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt; 

 f2str fb;

 *}

 ML {* (*check koeffizients*)

 if f2str fa = "[A = 4]" then () else error "part.fract. eq4_1";

 if f2str fb = "[B = -4]" then () else error "part.fract. eq4_1";

 *}

 subsubsection {*substitute expression with solutions*}

 ML {*

 *}

 section {*Implement the Specification and the Method*}

 text{*==============================================*}

 subsection{*Define the Field Descriptions for the specification*}

 consts

   filterExpression  :: "bool => una"

   stepResponse      :: "bool => una"

 subsection{*Define the Specification*}

 ML {*

 val thy = @{theory};

 *}

 ML {*

 store_pbt

  (prep_pbt thy "pbl_SP" [] e_pblID

  (["SignalProcessing"], [], e_rls, NONE, []));

 store_pbt

  (prep_pbt thy "pbl_SP_Ztrans" [] e_pblID

  (["Z_Transform","SignalProcessing"], [], e_rls, NONE, []));

 store_pbt

  (prep_pbt thy "pbl_SP_Ztrans_inv" [] e_pblID

  (["inverse", "Z_Transform", "SignalProcessing"],

   [("#Given" ,["filterExpression X_eq"]),

    ("#Find"  ,["stepResponse n_eq"])

   ],

   append_rls "e_rls" e_rls [(*for preds in where_*)], NONE, 

   [["SignalProcessing","Z_Transform","inverse"]]));

 show_ptyps();

 get_pbt ["inverse","Z_Transform","SignalProcessing"];

 *}

 subsection {*Define Name and Signature for the Method*}

 consts

   InverseZTransform :: "[bool, bool] => bool"

     ("((Script InverseZTransform (_ =))// (_))" 9)

 subsection {*Setup Parent Nodes in Hierarchy of Method*}

 ML {*

 store_met

  (prep_met thy "met_SP" [] e_metID

  (["SignalProcessing"], [],

    {rew_ord'="tless_true", rls'= e_rls, calc = [], srls = e_rls, prls = e_rls,

     crls = e_rls, nrls = e_rls}, "empty_script"));

 store_met

  (prep_met thy "met_SP_Ztrans" [] e_metID

  (["SignalProcessing", "Z_Transform"], [],

    {rew_ord'="tless_true", rls'= e_rls, calc = [], srls = e_rls, prls = e_rls,

     crls = e_rls, nrls = e_rls}, "empty_script"));

 *}

 ML {*

 val thy = @{theory}; (*latest version of thy required*)

 store_met

  (prep_met thy "met_SP_Ztrans_inv" [] e_metID

  (["SignalProcessing", "Z_Transform", "inverse"], 

   [("#Given" ,["filterExpression X_eq"]),

    ("#Find"  ,["stepResponse n_eq"])

   ],

    {rew_ord'="tless_true", rls'= e_rls, calc = [], srls = e_rls, prls = e_rls,

     crls = e_rls, nrls = e_rls},

   "Script InverseZTransform (Xeq::bool) =" ^

   " (let X = Take Xeq;" ^

   "      X = Rewrite ruleZY False X" ^

   "  in X)"

  ));

 show_mets();

 get_met ["SignalProcessing","Z_Transform","inverse"];

 *}

 section {*Program in CTP-based language*}

 text{*=================================*}

 subsection {*Stepwise extend Program*}

 ML {*

 val str = 

 "Script InverseZTransform (Xeq::bool) =" ^

 " Xeq";

 *}

 ML {*

 val str = 

 "Script InverseZTransform (Xeq::bool) =" ^ (*(1/z) instead of z ^^^ -1*)

 " (let X = Take Xeq;" ^

 "      X' = Rewrite ruleZY False X;" ^ (*z * denominator*)

 "      X' = (Rewrite_Set norm_Rational False) X'" ^ (*simplify*)

 "  in X)";

 (*NONE*)

 "Script InverseZTransform (Xeq::bool) =" ^ (*(1/z) instead of z ^^^ -1*)

 " (let X = Take Xeq;" ^

 "      X' = Rewrite ruleZY False X;" ^ (*z * denominator*)

 "      X' = (Rewrite_Set norm_Rational False) X';" ^ (*simplify*)

 "      X' = (SubProblem (Isac',[pqFormula,degree_2,polynomial,univariate,equation], [no_met])   " ^

     "                 [BOOL e_e, REAL v_v])" ^

 "  in X)";

 *}

 ML {*

 val str = 

 "Script InverseZTransform (Xeq::bool) =" ^ (*(1/z) instead of z ^^^ -1*)

 " (let X = Take Xeq;" ^

 "      X' = Rewrite ruleZY False X;" ^ (*z * denominator*)

 "      X' = (Rewrite_Set norm_Rational False) X';" ^ (*simplify*)

 "      funterm = rhs X'" ^ (*drop X'= for equation solving*)

 "  in X)";

 *}

 ML {*

 parse thy str;

 val sc = ((inst_abs thy) o term_of o the o (parse thy)) str;

 atomty sc;

 *}

 ML {*

 term2str sc;

 atomty sc

 *}

 subsection {*Store Final Version of Program for Execution*}

 ML {*

 store_met

  (prep_met thy "met_SP_Ztrans_inv" [] e_metID

  (["SignalProcessing", "Z_Transform", "inverse"], 

   [("#Given" ,["filterExpression X_eq"]),

    ("#Find"  ,["stepResponse n_eq"])

   ],

    {rew_ord'="tless_true", rls'= e_rls, calc = [], srls = e_rls, prls = e_rls,

     crls = e_rls, nrls = e_rls},

 "Script InverseZTransform (Xeq::bool) =" ^ (*(1/z) instead of z ^^^ -1*)

 " (let X = Take Xeq;" ^

 "      X' = Rewrite ruleZY False X;" ^ (*z * denominator*)

 "      X' = (Rewrite_Set norm_Rational False) X';" ^ (*simplify*)

 "      funterm = rhs X'" ^ (*drop X'= for equation solving*)

 "  in X)"

  ));

 *}

 subsection {*Stepwise Execute the Program*}

 ML {*

 parseNEW ctxt "stepResponse x[n]";

 Thy_Info.get_theory "Inverse_Z_Transform";

 *}

 ML {*

 print_depth 999; Thy_Info.get_names(); print_depth 999;

 *}

 ML {*

 (*val SOME func = parseNEW ctxt "X  = 3 / (z - 1/4 + -1/8 * (1/z))"; term2str fun1;*)

 val fmz = ["filterExpression (X  = 3 / (z - 1/4 + -1/8 * (1/z)))", "stepResponse x[n]"];

 val (dI,pI,mI) = ("Isac", ["inverse", "Z_Transform", "SignalProcessing"], 

   ["SignalProcessing","Z_Transform","inverse"]);

 val (p,_,fb,nxt,_,pt)  = CalcTreeTEST [(fmz, (dI,pI,mI))];

 *}

 ML {*

 get_met ["SignalProcessing","Z_Transform","inverse"];

 *}

 ML {*

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt

 *}

 ML {*

 f2str fb;

 *}

 ML {*

 val fmz = ["equality (3 = -3 * B / (4::real))", "solveFor B","solutions L"];

 val (dI,pI,mI) =("Isac", ["univariate","equation"], ["no_met"]);

 val (p,_,fb,nxt,_,pt) = CalcTreeTEST [(fmz, (dI,pI,mI))];

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 *}

 ML {*

 val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

 f2str fb;

 *}

 section {*Write Tests for Crucial Details*}

 text{*===================================*}

 ML {*

 *}

 section {*Integrate Program into Knowledge*}

 ML {*

 *}

 end