Definition Reval_formula (e: PolEnv R) (k: Tauto.kind) (ff : Formula Rcst) :=
  let (lhs,o,rhs) := ff in Reval_op2 k o (Reval_expr e lhs) (Reval_expr e rhs).Definition Reval_formula' :=
  eval_sformula  Rplus Rmult Rminus Ropp (@eq R) Rle Rlt N.to_nat pow R_of_Rcst.

Lemma Reval_formula_compat : forall env b f, Tauto.hold b (Reval_formula env b f) <-> Reval_formula' env f.