Definition INZ (n:N) : R :=
  match n with
    | N0 => IZR 0%Z
    | Npos p => IZR (Zpos p)
  end.Definition Reval_expr := eval_pexpr  Rplus Rmult Rminus Ropp R_of_Rcst N.to_nat pow.Definition Reval_pop2 (o:Op2) : R -> R -> Prop :=
    match o with
      | OpEq =>  @eq R
      | OpNEq => fun x y  => ~ x = y
      | OpLe => Rle
      | OpGe => Rge
      | OpLt => Rlt
      | OpGt => Rgt
    end.Definition sumboolb {A B : Prop} (x : @sumbool A B) : bool :=
  if x then true else false.Definition Reval_bop2 (o : Op2) : R -> R -> bool :=
  match o with
  | OpEq  => fun x y => sumboolb (Req_dec_T x y)
  | OpNEq => fun x y => negb (sumboolb (Req_dec_T x y))
  | OpLe  => fun x y => (sumboolb (Rle_lt_dec x y))
  | OpGe  => fun x y => (sumboolb (Rge_gt_dec x y))
  | OpLt  => fun x y => (sumboolb (Rlt_le_dec x y))
  | OpGt  => fun x y => (sumboolb (Rgt_dec x y))
  end.

Lemma pop2_bop2 : forall (op : Op2) (r1 r2 : R), is_true (Reval_bop2 op r1 r2) <-> Reval_pop2 op r1 r2.