src/HOL/Library/positivstellensatz.ML
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```     1 (*  Title:      HOL/Library/positivstellensatz.ML
```
```     2     Author:     Amine Chaieb, University of Cambridge
```
```     3
```
```     4 A generic arithmetic prover based on Positivstellensatz certificates
```
```     5 --- also implements Fourrier-Motzkin elimination as a special case
```
```     6 Fourrier-Motzkin elimination.
```
```     7 *)
```
```     8
```
```     9 (* A functor for finite mappings based on Tables *)
```
```    10
```
```    11 signature FUNC =
```
```    12 sig
```
```    13   include TABLE
```
```    14   val apply : 'a table -> key -> 'a
```
```    15   val applyd :'a table -> (key -> 'a) -> key -> 'a
```
```    16   val combine : ('a -> 'a -> 'a) -> ('a -> bool) -> 'a table -> 'a table -> 'a table
```
```    17   val dom : 'a table -> key list
```
```    18   val tryapplyd : 'a table -> key -> 'a -> 'a
```
```    19   val updatep : (key * 'a -> bool) -> key * 'a -> 'a table -> 'a table
```
```    20   val choose : 'a table -> key * 'a
```
```    21   val onefunc : key * 'a -> 'a table
```
```    22 end;
```
```    23
```
```    24 functor FuncFun(Key: KEY) : FUNC =
```
```    25 struct
```
```    26
```
```    27 structure Tab = Table(Key);
```
```    28
```
```    29 open Tab;
```
```    30
```
```    31 fun dom a = sort Key.ord (Tab.keys a);
```
```    32 fun applyd f d x = case Tab.lookup f x of
```
```    33    SOME y => y
```
```    34  | NONE => d x;
```
```    35
```
```    36 fun apply f x = applyd f (fn _ => raise Tab.UNDEF x) x;
```
```    37 fun tryapplyd f a d = applyd f (K d) a;
```
```    38 fun updatep p (k,v) t = if p (k, v) then t else update (k,v) t
```
```    39 fun combine f z a b =
```
```    40   let
```
```    41     fun h (k,v) t = case Tab.lookup t k of
```
```    42         NONE => Tab.update (k,v) t
```
```    43       | SOME v' => let val w = f v v'
```
```    44         in if z w then Tab.delete k t else Tab.update (k,w) t end;
```
```    45   in Tab.fold h a b end;
```
```    46
```
```    47 fun choose f =
```
```    48   (case Tab.min f of
```
```    49     SOME entry => entry
```
```    50   | NONE => error "FuncFun.choose : Completely empty function")
```
```    51
```
```    52 fun onefunc kv = update kv empty
```
```    53
```
```    54 end;
```
```    55
```
```    56 (* Some standard functors and utility functions for them *)
```
```    57
```
```    58 structure FuncUtil =
```
```    59 struct
```
```    60
```
```    61 structure Intfunc = FuncFun(type key = int val ord = int_ord);
```
```    62 structure Ratfunc = FuncFun(type key = Rat.rat val ord = Rat.ord);
```
```    63 structure Intpairfunc = FuncFun(type key = int*int val ord = prod_ord int_ord int_ord);
```
```    64 structure Symfunc = FuncFun(type key = string val ord = fast_string_ord);
```
```    65 structure Termfunc = FuncFun(type key = term val ord = Term_Ord.fast_term_ord);
```
```    66
```
```    67 val cterm_ord = Term_Ord.fast_term_ord o pairself term_of
```
```    68
```
```    69 structure Ctermfunc = FuncFun(type key = cterm val ord = cterm_ord);
```
```    70
```
```    71 type monomial = int Ctermfunc.table;
```
```    72
```
```    73 val monomial_ord = list_ord (prod_ord cterm_ord int_ord) o pairself Ctermfunc.dest
```
```    74
```
```    75 structure Monomialfunc = FuncFun(type key = monomial val ord = monomial_ord)
```
```    76
```
```    77 type poly = Rat.rat Monomialfunc.table;
```
```    78
```
```    79 (* The ordering so we can create canonical HOL polynomials.                  *)
```
```    80
```
```    81 fun dest_monomial mon = sort (cterm_ord o pairself fst) (Ctermfunc.dest mon);
```
```    82
```
```    83 fun monomial_order (m1,m2) =
```
```    84   if Ctermfunc.is_empty m2 then LESS
```
```    85   else if Ctermfunc.is_empty m1 then GREATER
```
```    86   else
```
```    87     let
```
```    88       val mon1 = dest_monomial m1
```
```    89       val mon2 = dest_monomial m2
```
```    90       val deg1 = fold (Integer.add o snd) mon1 0
```
```    91       val deg2 = fold (Integer.add o snd) mon2 0
```
```    92     in if deg1 < deg2 then GREATER
```
```    93        else if deg1 > deg2 then LESS
```
```    94        else list_ord (prod_ord cterm_ord int_ord) (mon1,mon2)
```
```    95     end;
```
```    96
```
```    97 end
```
```    98
```
```    99 (* positivstellensatz datatype and prover generation *)
```
```   100
```
```   101 signature REAL_ARITH =
```
```   102 sig
```
```   103
```
```   104   datatype positivstellensatz =
```
```   105     Axiom_eq of int
```
```   106   | Axiom_le of int
```
```   107   | Axiom_lt of int
```
```   108   | Rational_eq of Rat.rat
```
```   109   | Rational_le of Rat.rat
```
```   110   | Rational_lt of Rat.rat
```
```   111   | Square of FuncUtil.poly
```
```   112   | Eqmul of FuncUtil.poly * positivstellensatz
```
```   113   | Sum of positivstellensatz * positivstellensatz
```
```   114   | Product of positivstellensatz * positivstellensatz;
```
```   115
```
```   116   datatype pss_tree = Trivial | Cert of positivstellensatz | Branch of pss_tree * pss_tree
```
```   117
```
```   118   datatype tree_choice = Left | Right
```
```   119
```
```   120   type prover = tree_choice list ->
```
```   121     (thm list * thm list * thm list -> positivstellensatz -> thm) ->
```
```   122       thm list * thm list * thm list -> thm * pss_tree
```
```   123   type cert_conv = cterm -> thm * pss_tree
```
```   124
```
```   125   val gen_gen_real_arith :
```
```   126     Proof.context -> (Rat.rat -> cterm) * conv * conv * conv *
```
```   127      conv * conv * conv * conv * conv * conv * prover -> cert_conv
```
```   128   val real_linear_prover : (thm list * thm list * thm list -> positivstellensatz -> thm) ->
```
```   129     thm list * thm list * thm list -> thm * pss_tree
```
```   130
```
```   131   val gen_real_arith : Proof.context ->
```
```   132     (Rat.rat -> cterm) * conv * conv * conv * conv * conv * conv * conv * prover -> cert_conv
```
```   133
```
```   134   val gen_prover_real_arith : Proof.context -> prover -> cert_conv
```
```   135
```
```   136   val is_ratconst : cterm -> bool
```
```   137   val dest_ratconst : cterm -> Rat.rat
```
```   138   val cterm_of_rat : Rat.rat -> cterm
```
```   139
```
```   140 end
```
```   141
```
```   142 structure RealArith : REAL_ARITH =
```
```   143 struct
```
```   144
```
```   145 open Conv
```
```   146 (* ------------------------------------------------------------------------- *)
```
```   147 (* Data structure for Positivstellensatz refutations.                        *)
```
```   148 (* ------------------------------------------------------------------------- *)
```
```   149
```
```   150 datatype positivstellensatz =
```
```   151     Axiom_eq of int
```
```   152   | Axiom_le of int
```
```   153   | Axiom_lt of int
```
```   154   | Rational_eq of Rat.rat
```
```   155   | Rational_le of Rat.rat
```
```   156   | Rational_lt of Rat.rat
```
```   157   | Square of FuncUtil.poly
```
```   158   | Eqmul of FuncUtil.poly * positivstellensatz
```
```   159   | Sum of positivstellensatz * positivstellensatz
```
```   160   | Product of positivstellensatz * positivstellensatz;
```
```   161          (* Theorems used in the procedure *)
```
```   162
```
```   163 datatype pss_tree = Trivial | Cert of positivstellensatz | Branch of pss_tree * pss_tree
```
```   164 datatype tree_choice = Left | Right
```
```   165 type prover = tree_choice list ->
```
```   166   (thm list * thm list * thm list -> positivstellensatz -> thm) ->
```
```   167     thm list * thm list * thm list -> thm * pss_tree
```
```   168 type cert_conv = cterm -> thm * pss_tree
```
```   169
```
```   170
```
```   171     (* Some useful derived rules *)
```
```   172 fun deduct_antisym_rule tha thb =
```
```   173     Thm.equal_intr (Thm.implies_intr (cprop_of thb) tha)
```
```   174      (Thm.implies_intr (cprop_of tha) thb);
```
```   175
```
```   176 fun prove_hyp tha thb =
```
```   177   if exists (curry op aconv (concl_of tha)) (Thm.hyps_of thb)  (* FIXME !? *)
```
```   178   then Thm.equal_elim (Thm.symmetric (deduct_antisym_rule tha thb)) tha else thb;
```
```   179
```
```   180 val pth = @{lemma "(((x::real) < y) == (y - x > 0))" and "((x <= y) == (y - x >= 0))" and
```
```   181      "((x = y) == (x - y = 0))" and "((~(x < y)) == (x - y >= 0))" and
```
```   182      "((~(x <= y)) == (x - y > 0))" and "((~(x = y)) == (x - y > 0 | -(x - y) > 0))"
```
```   183   by (atomize (full), auto simp add: less_diff_eq le_diff_eq not_less)};
```
```   184
```
```   185 val pth_final = @{lemma "(~p ==> False) ==> p" by blast}
```
```   186 val pth_add =
```
```   187   @{lemma "(x = (0::real) ==> y = 0 ==> x + y = 0 )" and "( x = 0 ==> y >= 0 ==> x + y >= 0)" and
```
```   188     "(x = 0 ==> y > 0 ==> x + y > 0)" and "(x >= 0 ==> y = 0 ==> x + y >= 0)" and
```
```   189     "(x >= 0 ==> y >= 0 ==> x + y >= 0)" and "(x >= 0 ==> y > 0 ==> x + y > 0)" and
```
```   190     "(x > 0 ==> y = 0 ==> x + y > 0)" and "(x > 0 ==> y >= 0 ==> x + y > 0)" and
```
```   191     "(x > 0 ==> y > 0 ==> x + y > 0)" by simp_all};
```
```   192
```
```   193 val pth_mul =
```
```   194   @{lemma "(x = (0::real) ==> y = 0 ==> x * y = 0)" and "(x = 0 ==> y >= 0 ==> x * y = 0)" and
```
```   195     "(x = 0 ==> y > 0 ==> x * y = 0)" and "(x >= 0 ==> y = 0 ==> x * y = 0)" and
```
```   196     "(x >= 0 ==> y >= 0 ==> x * y >= 0)" and "(x >= 0 ==> y > 0 ==> x * y >= 0)" and
```
```   197     "(x > 0 ==>  y = 0 ==> x * y = 0)" and "(x > 0 ==> y >= 0 ==> x * y >= 0)" and
```
```   198     "(x > 0 ==>  y > 0 ==> x * y > 0)"
```
```   199   by (auto intro: mult_mono[where a="0::real" and b="x" and d="y" and c="0", simplified]
```
```   200     mult_strict_mono[where b="x" and d="y" and a="0" and c="0", simplified])};
```
```   201
```
```   202 val pth_emul = @{lemma "y = (0::real) ==> x * y = 0"  by simp};
```
```   203 val pth_square = @{lemma "x * x >= (0::real)"  by simp};
```
```   204
```
```   205 val weak_dnf_simps =
```
```   206   List.take (@{thms simp_thms}, 34) @
```
```   207     @{lemma "((P & (Q | R)) = ((P&Q) | (P&R)))" and "((Q | R) & P) = ((Q&P) | (R&P))" and
```
```   208       "(P & Q) = (Q & P)" and "((P | Q) = (Q | P))" by blast+};
```
```   209
```
```   210 (*
```
```   211 val nnfD_simps =
```
```   212   @{lemma "((~(P & Q)) = (~P | ~Q))" and "((~(P | Q)) = (~P & ~Q) )" and
```
```   213     "((P --> Q) = (~P | Q) )" and "((P = Q) = ((P & Q) | (~P & ~ Q)))" and
```
```   214     "((~(P = Q)) = ((P & ~ Q) | (~P & Q)) )" and "((~ ~(P)) = P)" by blast+};
```
```   215 *)
```
```   216
```
```   217 val choice_iff = @{lemma "(ALL x. EX y. P x y) = (EX f. ALL x. P x (f x))" by metis};
```
```   218 val prenex_simps =
```
```   219   map (fn th => th RS sym)
```
```   220     ([@{thm "all_conj_distrib"}, @{thm "ex_disj_distrib"}] @
```
```   221       @{thms "HOL.all_simps"(1-4)} @ @{thms "ex_simps"(1-4)});
```
```   222
```
```   223 val real_abs_thms1 = @{lemma
```
```   224   "((-1 * abs(x::real) >= r) = (-1 * x >= r & 1 * x >= r))" and
```
```   225   "((-1 * abs(x) + a >= r) = (a + -1 * x >= r & a + 1 * x >= r))" and
```
```   226   "((a + -1 * abs(x) >= r) = (a + -1 * x >= r & a + 1 * x >= r))" and
```
```   227   "((a + -1 * abs(x) + b >= r) = (a + -1 * x + b >= r & a + 1 * x + b >= r))" and
```
```   228   "((a + b + -1 * abs(x) >= r) = (a + b + -1 * x >= r & a + b + 1 * x >= r))" and
```
```   229   "((a + b + -1 * abs(x) + c >= r) = (a + b + -1 * x + c >= r & a + b + 1 * x + c >= r))" and
```
```   230   "((-1 * max x y >= r) = (-1 * x >= r & -1 * y >= r))" and
```
```   231   "((-1 * max x y + a >= r) = (a + -1 * x >= r & a + -1 * y >= r))" and
```
```   232   "((a + -1 * max x y >= r) = (a + -1 * x >= r & a + -1 * y >= r))" and
```
```   233   "((a + -1 * max x y + b >= r) = (a + -1 * x + b >= r & a + -1 * y  + b >= r))" and
```
```   234   "((a + b + -1 * max x y >= r) = (a + b + -1 * x >= r & a + b + -1 * y >= r))" and
```
```   235   "((a + b + -1 * max x y + c >= r) = (a + b + -1 * x + c >= r & a + b + -1 * y  + c >= r))" and
```
```   236   "((1 * min x y >= r) = (1 * x >= r & 1 * y >= r))" and
```
```   237   "((1 * min x y + a >= r) = (a + 1 * x >= r & a + 1 * y >= r))" and
```
```   238   "((a + 1 * min x y >= r) = (a + 1 * x >= r & a + 1 * y >= r))" and
```
```   239   "((a + 1 * min x y + b >= r) = (a + 1 * x + b >= r & a + 1 * y  + b >= r))" and
```
```   240   "((a + b + 1 * min x y >= r) = (a + b + 1 * x >= r & a + b + 1 * y >= r))" and
```
```   241   "((a + b + 1 * min x y + c >= r) = (a + b + 1 * x + c >= r & a + b + 1 * y  + c >= r))" and
```
```   242   "((min x y >= r) = (x >= r &  y >= r))" and
```
```   243   "((min x y + a >= r) = (a + x >= r & a + y >= r))" and
```
```   244   "((a + min x y >= r) = (a + x >= r & a + y >= r))" and
```
```   245   "((a + min x y + b >= r) = (a + x + b >= r & a + y  + b >= r))" and
```
```   246   "((a + b + min x y >= r) = (a + b + x >= r & a + b + y >= r))" and
```
```   247   "((a + b + min x y + c >= r) = (a + b + x + c >= r & a + b + y + c >= r))" and
```
```   248   "((-1 * abs(x) > r) = (-1 * x > r & 1 * x > r))" and
```
```   249   "((-1 * abs(x) + a > r) = (a + -1 * x > r & a + 1 * x > r))" and
```
```   250   "((a + -1 * abs(x) > r) = (a + -1 * x > r & a + 1 * x > r))" and
```
```   251   "((a + -1 * abs(x) + b > r) = (a + -1 * x + b > r & a + 1 * x + b > r))" and
```
```   252   "((a + b + -1 * abs(x) > r) = (a + b + -1 * x > r & a + b + 1 * x > r))" and
```
```   253   "((a + b + -1 * abs(x) + c > r) = (a + b + -1 * x + c > r & a + b + 1 * x + c > r))" and
```
```   254   "((-1 * max x y > r) = ((-1 * x > r) & -1 * y > r))" and
```
```   255   "((-1 * max x y + a > r) = (a + -1 * x > r & a + -1 * y > r))" and
```
```   256   "((a + -1 * max x y > r) = (a + -1 * x > r & a + -1 * y > r))" and
```
```   257   "((a + -1 * max x y + b > r) = (a + -1 * x + b > r & a + -1 * y  + b > r))" and
```
```   258   "((a + b + -1 * max x y > r) = (a + b + -1 * x > r & a + b + -1 * y > r))" and
```
```   259   "((a + b + -1 * max x y + c > r) = (a + b + -1 * x + c > r & a + b + -1 * y  + c > r))" and
```
```   260   "((min x y > r) = (x > r &  y > r))" and
```
```   261   "((min x y + a > r) = (a + x > r & a + y > r))" and
```
```   262   "((a + min x y > r) = (a + x > r & a + y > r))" and
```
```   263   "((a + min x y + b > r) = (a + x + b > r & a + y  + b > r))" and
```
```   264   "((a + b + min x y > r) = (a + b + x > r & a + b + y > r))" and
```
```   265   "((a + b + min x y + c > r) = (a + b + x + c > r & a + b + y + c > r))"
```
```   266   by auto};
```
```   267
```
```   268 val abs_split' = @{lemma "P (abs (x::'a::linordered_idom)) == (x >= 0 & P x | x < 0 & P (-x))"
```
```   269   by (atomize (full)) (auto split add: abs_split)};
```
```   270
```
```   271 val max_split = @{lemma "P (max x y) == ((x::'a::linorder) <= y & P y | x > y & P x)"
```
```   272   by (atomize (full)) (cases "x <= y", auto simp add: max_def)};
```
```   273
```
```   274 val min_split = @{lemma "P (min x y) == ((x::'a::linorder) <= y & P x | x > y & P y)"
```
```   275   by (atomize (full)) (cases "x <= y", auto simp add: min_def)};
```
```   276
```
```   277
```
```   278          (* Miscellaneous *)
```
```   279 fun literals_conv bops uops cv =
```
```   280   let
```
```   281     fun h t =
```
```   282       case (term_of t) of
```
```   283         b\$_\$_ => if member (op aconv) bops b then binop_conv h t else cv t
```
```   284       | u\$_ => if member (op aconv) uops u then arg_conv h t else cv t
```
```   285       | _ => cv t
```
```   286   in h end;
```
```   287
```
```   288 fun cterm_of_rat x =
```
```   289   let
```
```   290     val (a, b) = Rat.quotient_of_rat x
```
```   291   in
```
```   292     if b = 1 then Numeral.mk_cnumber @{ctyp "real"} a
```
```   293     else Thm.apply (Thm.apply @{cterm "op / :: real => _"}
```
```   294       (Numeral.mk_cnumber @{ctyp "real"} a))
```
```   295       (Numeral.mk_cnumber @{ctyp "real"} b)
```
```   296   end;
```
```   297
```
```   298 fun dest_ratconst t =
```
```   299   case term_of t of
```
```   300     Const(@{const_name divide}, _)\$a\$b => Rat.rat_of_quotient(HOLogic.dest_number a |> snd, HOLogic.dest_number b |> snd)
```
```   301   | _ => Rat.rat_of_int (HOLogic.dest_number (term_of t) |> snd)
```
```   302 fun is_ratconst t = can dest_ratconst t
```
```   303
```
```   304 (*
```
```   305 fun find_term p t = if p t then t else
```
```   306  case t of
```
```   307   a\$b => (find_term p a handle TERM _ => find_term p b)
```
```   308  | Abs (_,_,t') => find_term p t'
```
```   309  | _ => raise TERM ("find_term",[t]);
```
```   310 *)
```
```   311
```
```   312 fun find_cterm p t =
```
```   313   if p t then t else
```
```   314   case term_of t of
```
```   315     _\$_ => (find_cterm p (Thm.dest_fun t) handle CTERM _ => find_cterm p (Thm.dest_arg t))
```
```   316   | Abs (_,_,_) => find_cterm p (Thm.dest_abs NONE t |> snd)
```
```   317   | _ => raise CTERM ("find_cterm",[t]);
```
```   318
```
```   319     (* Some conversions-related stuff which has been forbidden entrance into Pure/conv.ML*)
```
```   320 fun instantiate_cterm' ty tms = Drule.cterm_rule (Drule.instantiate' ty tms)
```
```   321 fun is_comb t = case (term_of t) of _\$_ => true | _ => false;
```
```   322
```
```   323 fun is_binop ct ct' = ct aconvc (Thm.dest_fun (Thm.dest_fun ct'))
```
```   324   handle CTERM _ => false;
```
```   325
```
```   326
```
```   327 (* Map back polynomials to HOL.                         *)
```
```   328
```
```   329 fun cterm_of_varpow x k = if k = 1 then x else Thm.apply (Thm.apply @{cterm "op ^ :: real => _"} x)
```
```   330   (Numeral.mk_cnumber @{ctyp nat} k)
```
```   331
```
```   332 fun cterm_of_monomial m =
```
```   333   if FuncUtil.Ctermfunc.is_empty m then @{cterm "1::real"}
```
```   334   else
```
```   335     let
```
```   336       val m' = FuncUtil.dest_monomial m
```
```   337       val vps = fold_rev (fn (x,k) => cons (cterm_of_varpow x k)) m' []
```
```   338     in foldr1 (fn (s, t) => Thm.apply (Thm.apply @{cterm "op * :: real => _"} s) t) vps
```
```   339     end
```
```   340
```
```   341 fun cterm_of_cmonomial (m,c) =
```
```   342   if FuncUtil.Ctermfunc.is_empty m then cterm_of_rat c
```
```   343   else if c = Rat.one then cterm_of_monomial m
```
```   344   else Thm.apply (Thm.apply @{cterm "op *::real => _"} (cterm_of_rat c)) (cterm_of_monomial m);
```
```   345
```
```   346 fun cterm_of_poly p =
```
```   347   if FuncUtil.Monomialfunc.is_empty p then @{cterm "0::real"}
```
```   348   else
```
```   349     let
```
```   350       val cms = map cterm_of_cmonomial
```
```   351         (sort (prod_ord FuncUtil.monomial_order (K EQUAL)) (FuncUtil.Monomialfunc.dest p))
```
```   352     in foldr1 (fn (t1, t2) => Thm.apply(Thm.apply @{cterm "op + :: real => _"} t1) t2) cms
```
```   353     end;
```
```   354
```
```   355 (* A general real arithmetic prover *)
```
```   356
```
```   357 fun gen_gen_real_arith ctxt (mk_numeric,
```
```   358        numeric_eq_conv,numeric_ge_conv,numeric_gt_conv,
```
```   359        poly_conv,poly_neg_conv,poly_add_conv,poly_mul_conv,
```
```   360        absconv1,absconv2,prover) =
```
```   361   let
```
```   362     val pre_ss = put_simpset HOL_basic_ss ctxt addsimps
```
```   363       @{thms simp_thms ex_simps all_simps not_all not_ex ex_disj_distrib all_conj_distrib if_bool_eq_disj}
```
```   364     val prenex_ss = put_simpset HOL_basic_ss ctxt addsimps prenex_simps
```
```   365     val skolemize_ss = put_simpset HOL_basic_ss ctxt addsimps [choice_iff]
```
```   366     val presimp_conv = Simplifier.rewrite pre_ss
```
```   367     val prenex_conv = Simplifier.rewrite prenex_ss
```
```   368     val skolemize_conv = Simplifier.rewrite skolemize_ss
```
```   369     val weak_dnf_ss = put_simpset HOL_basic_ss ctxt addsimps weak_dnf_simps
```
```   370     val weak_dnf_conv = Simplifier.rewrite weak_dnf_ss
```
```   371     fun eqT_elim th = Thm.equal_elim (Thm.symmetric th) @{thm TrueI}
```
```   372     fun oprconv cv ct =
```
```   373       let val g = Thm.dest_fun2 ct
```
```   374       in if g aconvc @{cterm "op <= :: real => _"}
```
```   375             orelse g aconvc @{cterm "op < :: real => _"}
```
```   376          then arg_conv cv ct else arg1_conv cv ct
```
```   377       end
```
```   378
```
```   379     fun real_ineq_conv th ct =
```
```   380       let
```
```   381         val th' = (Thm.instantiate (Thm.match (Thm.lhs_of th, ct)) th
```
```   382           handle Pattern.MATCH => raise CTERM ("real_ineq_conv", [ct]))
```
```   383       in Thm.transitive th' (oprconv poly_conv (Thm.rhs_of th'))
```
```   384       end
```
```   385     val [real_lt_conv, real_le_conv, real_eq_conv,
```
```   386          real_not_lt_conv, real_not_le_conv, _] =
```
```   387          map real_ineq_conv pth
```
```   388     fun match_mp_rule ths ths' =
```
```   389       let
```
```   390         fun f ths ths' = case ths of [] => raise THM("match_mp_rule",0,ths)
```
```   391           | th::ths => (ths' MRS th handle THM _ => f ths ths')
```
```   392       in f ths ths' end
```
```   393     fun mul_rule th th' = fconv_rule (arg_conv (oprconv poly_mul_conv))
```
```   394          (match_mp_rule pth_mul [th, th'])
```
```   395     fun add_rule th th' = fconv_rule (arg_conv (oprconv poly_add_conv))
```
```   396          (match_mp_rule pth_add [th, th'])
```
```   397     fun emul_rule ct th = fconv_rule (arg_conv (oprconv poly_mul_conv))
```
```   398        (instantiate' [] [SOME ct] (th RS pth_emul))
```
```   399     fun square_rule t = fconv_rule (arg_conv (oprconv poly_conv))
```
```   400        (instantiate' [] [SOME t] pth_square)
```
```   401
```
```   402     fun hol_of_positivstellensatz(eqs,les,lts) proof =
```
```   403       let
```
```   404         fun translate prf =
```
```   405           case prf of
```
```   406             Axiom_eq n => nth eqs n
```
```   407           | Axiom_le n => nth les n
```
```   408           | Axiom_lt n => nth lts n
```
```   409           | Rational_eq x => eqT_elim(numeric_eq_conv(Thm.apply @{cterm Trueprop}
```
```   410                           (Thm.apply (Thm.apply @{cterm "op =::real => _"} (mk_numeric x))
```
```   411                                @{cterm "0::real"})))
```
```   412           | Rational_le x => eqT_elim(numeric_ge_conv(Thm.apply @{cterm Trueprop}
```
```   413                           (Thm.apply (Thm.apply @{cterm "op <=::real => _"}
```
```   414                                      @{cterm "0::real"}) (mk_numeric x))))
```
```   415           | Rational_lt x => eqT_elim(numeric_gt_conv(Thm.apply @{cterm Trueprop}
```
```   416                       (Thm.apply (Thm.apply @{cterm "op <::real => _"} @{cterm "0::real"})
```
```   417                         (mk_numeric x))))
```
```   418           | Square pt => square_rule (cterm_of_poly pt)
```
```   419           | Eqmul(pt,p) => emul_rule (cterm_of_poly pt) (translate p)
```
```   420           | Sum(p1,p2) => add_rule (translate p1) (translate p2)
```
```   421           | Product(p1,p2) => mul_rule (translate p1) (translate p2)
```
```   422       in fconv_rule (first_conv [numeric_ge_conv, numeric_gt_conv, numeric_eq_conv, all_conv])
```
```   423           (translate proof)
```
```   424       end
```
```   425
```
```   426     val init_conv = presimp_conv then_conv
```
```   427         nnf_conv ctxt then_conv skolemize_conv then_conv prenex_conv then_conv
```
```   428         weak_dnf_conv
```
```   429
```
```   430     val concl = Thm.dest_arg o cprop_of
```
```   431     fun is_binop opr ct = (Thm.dest_fun2 ct aconvc opr handle CTERM _ => false)
```
```   432     val is_req = is_binop @{cterm "op =:: real => _"}
```
```   433     val is_ge = is_binop @{cterm "op <=:: real => _"}
```
```   434     val is_gt = is_binop @{cterm "op <:: real => _"}
```
```   435     val is_conj = is_binop @{cterm HOL.conj}
```
```   436     val is_disj = is_binop @{cterm HOL.disj}
```
```   437     fun conj_pair th = (th RS @{thm conjunct1}, th RS @{thm conjunct2})
```
```   438     fun disj_cases th th1 th2 =
```
```   439       let
```
```   440         val (p,q) = Thm.dest_binop (concl th)
```
```   441         val c = concl th1
```
```   442         val _ = if c aconvc (concl th2) then () else error "disj_cases : conclusions not alpha convertible"
```
```   443       in Thm.implies_elim (Thm.implies_elim
```
```   444           (Thm.implies_elim (instantiate' [] (map SOME [p,q,c]) @{thm disjE}) th)
```
```   445           (Thm.implies_intr (Thm.apply @{cterm Trueprop} p) th1))
```
```   446         (Thm.implies_intr (Thm.apply @{cterm Trueprop} q) th2)
```
```   447       end
```
```   448     fun overall cert_choice dun ths =
```
```   449       case ths of
```
```   450         [] =>
```
```   451         let
```
```   452           val (eq,ne) = List.partition (is_req o concl) dun
```
```   453           val (le,nl) = List.partition (is_ge o concl) ne
```
```   454           val lt = filter (is_gt o concl) nl
```
```   455         in prover (rev cert_choice) hol_of_positivstellensatz (eq,le,lt) end
```
```   456       | th::oths =>
```
```   457         let
```
```   458           val ct = concl th
```
```   459         in
```
```   460           if is_conj ct then
```
```   461             let
```
```   462               val (th1,th2) = conj_pair th
```
```   463             in overall cert_choice dun (th1::th2::oths) end
```
```   464           else if is_disj ct then
```
```   465             let
```
```   466               val (th1, cert1) = overall (Left::cert_choice) dun (Thm.assume (Thm.apply @{cterm Trueprop} (Thm.dest_arg1 ct))::oths)
```
```   467               val (th2, cert2) = overall (Right::cert_choice) dun (Thm.assume (Thm.apply @{cterm Trueprop} (Thm.dest_arg ct))::oths)
```
```   468             in (disj_cases th th1 th2, Branch (cert1, cert2)) end
```
```   469           else overall cert_choice (th::dun) oths
```
```   470         end
```
```   471     fun dest_binary b ct =
```
```   472         if is_binop b ct then Thm.dest_binop ct
```
```   473         else raise CTERM ("dest_binary",[b,ct])
```
```   474     val dest_eq = dest_binary @{cterm "op = :: real => _"}
```
```   475     val neq_th = nth pth 5
```
```   476     fun real_not_eq_conv ct =
```
```   477       let
```
```   478         val (l,r) = dest_eq (Thm.dest_arg ct)
```
```   479         val th = Thm.instantiate ([],[(@{cpat "?x::real"},l),(@{cpat "?y::real"},r)]) neq_th
```
```   480         val th_p = poly_conv(Thm.dest_arg(Thm.dest_arg1(Thm.rhs_of th)))
```
```   481         val th_x = Drule.arg_cong_rule @{cterm "uminus :: real => _"} th_p
```
```   482         val th_n = fconv_rule (arg_conv poly_neg_conv) th_x
```
```   483         val th' = Drule.binop_cong_rule @{cterm HOL.disj}
```
```   484           (Drule.arg_cong_rule (Thm.apply @{cterm "op <::real=>_"} @{cterm "0::real"}) th_p)
```
```   485           (Drule.arg_cong_rule (Thm.apply @{cterm "op <::real=>_"} @{cterm "0::real"}) th_n)
```
```   486       in Thm.transitive th th'
```
```   487       end
```
```   488     fun equal_implies_1_rule PQ =
```
```   489       let
```
```   490         val P = Thm.lhs_of PQ
```
```   491       in Thm.implies_intr P (Thm.equal_elim PQ (Thm.assume P))
```
```   492       end
```
```   493     (* FIXME!!! Copied from groebner.ml *)
```
```   494     val strip_exists =
```
```   495       let
```
```   496         fun h (acc, t) =
```
```   497           case (term_of t) of
```
```   498             Const(@{const_name Ex},_)\$Abs(_,_,_) => h (Thm.dest_abs NONE (Thm.dest_arg t) |>> (fn v => v::acc))
```
```   499           | _ => (acc,t)
```
```   500       in fn t => h ([],t)
```
```   501       end
```
```   502     fun name_of x =
```
```   503       case term_of x of
```
```   504         Free(s,_) => s
```
```   505       | Var ((s,_),_) => s
```
```   506       | _ => "x"
```
```   507
```
```   508     fun mk_forall x th = Drule.arg_cong_rule (instantiate_cterm' [SOME (ctyp_of_term x)] [] @{cpat "All :: (?'a => bool) => _" }) (Thm.abstract_rule (name_of x) x th)
```
```   509
```
```   510     val specl = fold_rev (fn x => fn th => instantiate' [] [SOME x] (th RS spec));
```
```   511
```
```   512     fun ext T = Drule.cterm_rule (instantiate' [SOME T] []) @{cpat Ex}
```
```   513     fun mk_ex v t = Thm.apply (ext (ctyp_of_term v)) (Thm.lambda v t)
```
```   514
```
```   515     fun choose v th th' =
```
```   516       case concl_of th of
```
```   517         @{term Trueprop} \$ (Const(@{const_name Ex},_)\$_) =>
```
```   518         let
```
```   519           val p = (funpow 2 Thm.dest_arg o cprop_of) th
```
```   520           val T = (hd o Thm.dest_ctyp o ctyp_of_term) p
```
```   521           val th0 = fconv_rule (Thm.beta_conversion true)
```
```   522             (instantiate' [SOME T] [SOME p, (SOME o Thm.dest_arg o cprop_of) th'] exE)
```
```   523           val pv = (Thm.rhs_of o Thm.beta_conversion true)
```
```   524             (Thm.apply @{cterm Trueprop} (Thm.apply p v))
```
```   525           val th1 = Thm.forall_intr v (Thm.implies_intr pv th')
```
```   526         in Thm.implies_elim (Thm.implies_elim th0 th) th1  end
```
```   527       | _ => raise THM ("choose",0,[th, th'])
```
```   528
```
```   529     fun simple_choose v th =
```
```   530       choose v (Thm.assume ((Thm.apply @{cterm Trueprop} o mk_ex v) ((Thm.dest_arg o hd o #hyps o Thm.crep_thm) th))) th
```
```   531
```
```   532     val strip_forall =
```
```   533       let
```
```   534         fun h (acc, t) =
```
```   535           case (term_of t) of
```
```   536             Const(@{const_name All},_)\$Abs(_,_,_) => h (Thm.dest_abs NONE (Thm.dest_arg t) |>> (fn v => v::acc))
```
```   537           | _ => (acc,t)
```
```   538       in fn t => h ([],t)
```
```   539       end
```
```   540
```
```   541     fun f ct =
```
```   542       let
```
```   543         val nnf_norm_conv' =
```
```   544           nnf_conv ctxt then_conv
```
```   545           literals_conv [@{term HOL.conj}, @{term HOL.disj}] []
```
```   546           (Conv.cache_conv
```
```   547             (first_conv [real_lt_conv, real_le_conv,
```
```   548                          real_eq_conv, real_not_lt_conv,
```
```   549                          real_not_le_conv, real_not_eq_conv, all_conv]))
```
```   550         fun absremover ct = (literals_conv [@{term HOL.conj}, @{term HOL.disj}] []
```
```   551                   (try_conv (absconv1 then_conv binop_conv (arg_conv poly_conv))) then_conv
```
```   552                   try_conv (absconv2 then_conv nnf_norm_conv' then_conv binop_conv absremover)) ct
```
```   553         val nct = Thm.apply @{cterm Trueprop} (Thm.apply @{cterm "Not"} ct)
```
```   554         val th0 = (init_conv then_conv arg_conv nnf_norm_conv') nct
```
```   555         val tm0 = Thm.dest_arg (Thm.rhs_of th0)
```
```   556         val (th, certificates) =
```
```   557           if tm0 aconvc @{cterm False} then (equal_implies_1_rule th0, Trivial) else
```
```   558           let
```
```   559             val (evs,bod) = strip_exists tm0
```
```   560             val (avs,ibod) = strip_forall bod
```
```   561             val th1 = Drule.arg_cong_rule @{cterm Trueprop} (fold mk_forall avs (absremover ibod))
```
```   562             val (th2, certs) = overall [] [] [specl avs (Thm.assume (Thm.rhs_of th1))]
```
```   563             val th3 = fold simple_choose evs (prove_hyp (Thm.equal_elim th1 (Thm.assume (Thm.apply @{cterm Trueprop} bod))) th2)
```
```   564           in (Drule.implies_intr_hyps (prove_hyp (Thm.equal_elim th0 (Thm.assume nct)) th3), certs)
```
```   565           end
```
```   566       in (Thm.implies_elim (instantiate' [] [SOME ct] pth_final) th, certificates)
```
```   567       end
```
```   568   in f
```
```   569   end;
```
```   570
```
```   571 (* A linear arithmetic prover *)
```
```   572 local
```
```   573   val linear_add = FuncUtil.Ctermfunc.combine (curry op +/) (fn z => z =/ Rat.zero)
```
```   574   fun linear_cmul c = FuncUtil.Ctermfunc.map (fn _ => fn x => c */ x)
```
```   575   val one_tm = @{cterm "1::real"}
```
```   576   fun contradictory p (e,_) = ((FuncUtil.Ctermfunc.is_empty e) andalso not(p Rat.zero)) orelse
```
```   577      ((eq_set (op aconvc) (FuncUtil.Ctermfunc.dom e, [one_tm])) andalso
```
```   578        not(p(FuncUtil.Ctermfunc.apply e one_tm)))
```
```   579
```
```   580   fun linear_ineqs vars (les,lts) =
```
```   581     case find_first (contradictory (fn x => x >/ Rat.zero)) lts of
```
```   582       SOME r => r
```
```   583     | NONE =>
```
```   584       (case find_first (contradictory (fn x => x >/ Rat.zero)) les of
```
```   585          SOME r => r
```
```   586        | NONE =>
```
```   587          if null vars then error "linear_ineqs: no contradiction" else
```
```   588          let
```
```   589            val ineqs = les @ lts
```
```   590            fun blowup v =
```
```   591              length(filter (fn (e,_) => FuncUtil.Ctermfunc.tryapplyd e v Rat.zero =/ Rat.zero) ineqs) +
```
```   592              length(filter (fn (e,_) => FuncUtil.Ctermfunc.tryapplyd e v Rat.zero >/ Rat.zero) ineqs) *
```
```   593              length(filter (fn (e,_) => FuncUtil.Ctermfunc.tryapplyd e v Rat.zero </ Rat.zero) ineqs)
```
```   594            val v = fst(hd(sort (fn ((_,i),(_,j)) => int_ord (i,j))
```
```   595              (map (fn v => (v,blowup v)) vars)))
```
```   596            fun addup (e1,p1) (e2,p2) acc =
```
```   597              let
```
```   598                val c1 = FuncUtil.Ctermfunc.tryapplyd e1 v Rat.zero
```
```   599                val c2 = FuncUtil.Ctermfunc.tryapplyd e2 v Rat.zero
```
```   600              in
```
```   601                if c1 */ c2 >=/ Rat.zero then acc else
```
```   602                let
```
```   603                  val e1' = linear_cmul (Rat.abs c2) e1
```
```   604                  val e2' = linear_cmul (Rat.abs c1) e2
```
```   605                  val p1' = Product(Rational_lt(Rat.abs c2),p1)
```
```   606                  val p2' = Product(Rational_lt(Rat.abs c1),p2)
```
```   607                in (linear_add e1' e2',Sum(p1',p2'))::acc
```
```   608                end
```
```   609              end
```
```   610            val (les0,les1) =
```
```   611              List.partition (fn (e,_) => FuncUtil.Ctermfunc.tryapplyd e v Rat.zero =/ Rat.zero) les
```
```   612            val (lts0,lts1) =
```
```   613              List.partition (fn (e,_) => FuncUtil.Ctermfunc.tryapplyd e v Rat.zero =/ Rat.zero) lts
```
```   614            val (lesp,lesn) =
```
```   615              List.partition (fn (e,_) => FuncUtil.Ctermfunc.tryapplyd e v Rat.zero >/ Rat.zero) les1
```
```   616            val (ltsp,ltsn) =
```
```   617              List.partition (fn (e,_) => FuncUtil.Ctermfunc.tryapplyd e v Rat.zero >/ Rat.zero) lts1
```
```   618            val les' = fold_rev (fn ep1 => fold_rev (addup ep1) lesp) lesn les0
```
```   619            val lts' = fold_rev (fn ep1 => fold_rev (addup ep1) (lesp@ltsp)) ltsn
```
```   620                       (fold_rev (fn ep1 => fold_rev (addup ep1) (lesn@ltsn)) ltsp lts0)
```
```   621          in linear_ineqs (remove (op aconvc) v vars) (les',lts')
```
```   622          end)
```
```   623
```
```   624   fun linear_eqs(eqs,les,lts) =
```
```   625     case find_first (contradictory (fn x => x =/ Rat.zero)) eqs of
```
```   626       SOME r => r
```
```   627     | NONE =>
```
```   628       (case eqs of
```
```   629          [] =>
```
```   630          let val vars = remove (op aconvc) one_tm
```
```   631              (fold_rev (union (op aconvc) o FuncUtil.Ctermfunc.dom o fst) (les@lts) [])
```
```   632          in linear_ineqs vars (les,lts) end
```
```   633        | (e,p)::es =>
```
```   634          if FuncUtil.Ctermfunc.is_empty e then linear_eqs (es,les,lts) else
```
```   635          let
```
```   636            val (x,c) = FuncUtil.Ctermfunc.choose (FuncUtil.Ctermfunc.delete_safe one_tm e)
```
```   637            fun xform (inp as (t,q)) =
```
```   638              let val d = FuncUtil.Ctermfunc.tryapplyd t x Rat.zero in
```
```   639                if d =/ Rat.zero then inp else
```
```   640                let
```
```   641                  val k = (Rat.neg d) */ Rat.abs c // c
```
```   642                  val e' = linear_cmul k e
```
```   643                  val t' = linear_cmul (Rat.abs c) t
```
```   644                  val p' = Eqmul(FuncUtil.Monomialfunc.onefunc (FuncUtil.Ctermfunc.empty, k),p)
```
```   645                  val q' = Product(Rational_lt(Rat.abs c),q)
```
```   646                in (linear_add e' t',Sum(p',q'))
```
```   647                end
```
```   648              end
```
```   649          in linear_eqs(map xform es,map xform les,map xform lts)
```
```   650          end)
```
```   651
```
```   652   fun linear_prover (eq,le,lt) =
```
```   653     let
```
```   654       val eqs = map_index (fn (n, p) => (p,Axiom_eq n)) eq
```
```   655       val les = map_index (fn (n, p) => (p,Axiom_le n)) le
```
```   656       val lts = map_index (fn (n, p) => (p,Axiom_lt n)) lt
```
```   657     in linear_eqs(eqs,les,lts)
```
```   658     end
```
```   659
```
```   660   fun lin_of_hol ct =
```
```   661     if ct aconvc @{cterm "0::real"} then FuncUtil.Ctermfunc.empty
```
```   662     else if not (is_comb ct) then FuncUtil.Ctermfunc.onefunc (ct, Rat.one)
```
```   663     else if is_ratconst ct then FuncUtil.Ctermfunc.onefunc (one_tm, dest_ratconst ct)
```
```   664     else
```
```   665       let val (lop,r) = Thm.dest_comb ct
```
```   666       in
```
```   667         if not (is_comb lop) then FuncUtil.Ctermfunc.onefunc (ct, Rat.one)
```
```   668         else
```
```   669           let val (opr,l) = Thm.dest_comb lop
```
```   670           in
```
```   671             if opr aconvc @{cterm "op + :: real =>_"}
```
```   672             then linear_add (lin_of_hol l) (lin_of_hol r)
```
```   673             else if opr aconvc @{cterm "op * :: real =>_"}
```
```   674                     andalso is_ratconst l then FuncUtil.Ctermfunc.onefunc (r, dest_ratconst l)
```
```   675             else FuncUtil.Ctermfunc.onefunc (ct, Rat.one)
```
```   676           end
```
```   677       end
```
```   678
```
```   679   fun is_alien ct =
```
```   680       case term_of ct of
```
```   681         Const(@{const_name "real"}, _)\$ n =>
```
```   682         if can HOLogic.dest_number n then false else true
```
```   683       | _ => false
```
```   684 in
```
```   685 fun real_linear_prover translator (eq,le,lt) =
```
```   686   let
```
```   687     val lhs = lin_of_hol o Thm.dest_arg1 o Thm.dest_arg o cprop_of
```
```   688     val rhs = lin_of_hol o Thm.dest_arg o Thm.dest_arg o cprop_of
```
```   689     val eq_pols = map lhs eq
```
```   690     val le_pols = map rhs le
```
```   691     val lt_pols = map rhs lt
```
```   692     val aliens = filter is_alien
```
```   693       (fold_rev (union (op aconvc) o FuncUtil.Ctermfunc.dom)
```
```   694                 (eq_pols @ le_pols @ lt_pols) [])
```
```   695     val le_pols' = le_pols @ map (fn v => FuncUtil.Ctermfunc.onefunc (v,Rat.one)) aliens
```
```   696     val (_,proof) = linear_prover (eq_pols,le_pols',lt_pols)
```
```   697     val le' = le @ map (fn a => instantiate' [] [SOME (Thm.dest_arg a)] @{thm real_of_nat_ge_zero}) aliens
```
```   698   in ((translator (eq,le',lt) proof), Trivial)
```
```   699   end
```
```   700 end;
```
```   701
```
```   702 (* A less general generic arithmetic prover dealing with abs,max and min*)
```
```   703
```
```   704 local
```
```   705   val absmaxmin_elim_ss1 =
```
```   706     simpset_of (put_simpset HOL_basic_ss @{context} addsimps real_abs_thms1)
```
```   707   fun absmaxmin_elim_conv1 ctxt =
```
```   708     Simplifier.rewrite (put_simpset absmaxmin_elim_ss1 ctxt)
```
```   709
```
```   710   val absmaxmin_elim_conv2 =
```
```   711     let
```
```   712       val pth_abs = instantiate' [SOME @{ctyp real}] [] abs_split'
```
```   713       val pth_max = instantiate' [SOME @{ctyp real}] [] max_split
```
```   714       val pth_min = instantiate' [SOME @{ctyp real}] [] min_split
```
```   715       val abs_tm = @{cterm "abs :: real => _"}
```
```   716       val p_tm = @{cpat "?P :: real => bool"}
```
```   717       val x_tm = @{cpat "?x :: real"}
```
```   718       val y_tm = @{cpat "?y::real"}
```
```   719       val is_max = is_binop @{cterm "max :: real => _"}
```
```   720       val is_min = is_binop @{cterm "min :: real => _"}
```
```   721       fun is_abs t = is_comb t andalso Thm.dest_fun t aconvc abs_tm
```
```   722       fun eliminate_construct p c tm =
```
```   723         let
```
```   724           val t = find_cterm p tm
```
```   725           val th0 = (Thm.symmetric o Thm.beta_conversion false) (Thm.apply (Thm.lambda t tm) t)
```
```   726           val (p,ax) = (Thm.dest_comb o Thm.rhs_of) th0
```
```   727         in fconv_rule(arg_conv(binop_conv (arg_conv (Thm.beta_conversion false))))
```
```   728                      (Thm.transitive th0 (c p ax))
```
```   729         end
```
```   730
```
```   731       val elim_abs = eliminate_construct is_abs
```
```   732         (fn p => fn ax =>
```
```   733           Thm.instantiate ([], [(p_tm,p), (x_tm, Thm.dest_arg ax)]) pth_abs)
```
```   734       val elim_max = eliminate_construct is_max
```
```   735         (fn p => fn ax =>
```
```   736           let val (ax,y) = Thm.dest_comb ax
```
```   737           in Thm.instantiate ([], [(p_tm,p), (x_tm, Thm.dest_arg ax), (y_tm,y)])
```
```   738                              pth_max end)
```
```   739       val elim_min = eliminate_construct is_min
```
```   740         (fn p => fn ax =>
```
```   741           let val (ax,y) = Thm.dest_comb ax
```
```   742           in Thm.instantiate ([], [(p_tm,p), (x_tm, Thm.dest_arg ax), (y_tm,y)])
```
```   743                              pth_min end)
```
```   744     in first_conv [elim_abs, elim_max, elim_min, all_conv]
```
```   745     end;
```
```   746 in
```
```   747 fun gen_real_arith ctxt (mkconst,eq,ge,gt,norm,neg,add,mul,prover) =
```
```   748   gen_gen_real_arith ctxt
```
```   749     (mkconst,eq,ge,gt,norm,neg,add,mul,
```
```   750      absmaxmin_elim_conv1 ctxt,absmaxmin_elim_conv2,prover)
```
```   751 end;
```
```   752
```
```   753 (* An instance for reals*)
```
```   754
```
```   755 fun gen_prover_real_arith ctxt prover =
```
```   756   let
```
```   757     fun simple_cterm_ord t u = Term_Ord.term_ord (term_of t, term_of u) = LESS
```
```   758     val {add, mul, neg, pow = _, sub = _, main} =
```
```   759         Semiring_Normalizer.semiring_normalizers_ord_wrapper ctxt
```
```   760         (the (Semiring_Normalizer.match ctxt @{cterm "(0::real) + 1"}))
```
```   761         simple_cterm_ord
```
```   762   in gen_real_arith ctxt
```
```   763      (cterm_of_rat,
```
```   764       Numeral_Simprocs.field_comp_conv ctxt,
```
```   765       Numeral_Simprocs.field_comp_conv ctxt,
```
```   766       Numeral_Simprocs.field_comp_conv ctxt,
```
```   767       main ctxt, neg ctxt, add ctxt, mul ctxt, prover)
```
```   768   end;
```
```   769
```
```   770 end
```