Ltac inv H := inversion H ; try subst ; clear H.(* roughly speaking, normalise_pexpr_correct is a proof of
  forall env p, eval_pexpr env p == eval_pol env (normalise_pexpr p) *)

(*****)
Definition paddC := PaddC cplus.Definition psubC := PsubC cminus.Definition PsubC_ok : forall c P env, eval_pol env (psubC  P c) == eval_pol env P - [c] :=
  let Rops_wd := mk_reqe (*rplus rtimes ropp req*)
                       (SORplus_wd sor)
                       (SORtimes_wd sor)
                       (SORopp_wd sor) in
                       PsubC_ok (SORsetoid sor) Rops_wd (Rth_ARth (SORsetoid sor) Rops_wd (SORrt sor))
                (SORrm addon).Definition PaddC_ok : forall c P env, eval_pol env (paddC  P c) == eval_pol env P + [c] :=
  let Rops_wd := mk_reqe (*rplus rtimes ropp req*)
                       (SORplus_wd sor)
                       (SORtimes_wd sor)
                       (SORopp_wd sor) in
                       PaddC_ok (SORsetoid sor) Rops_wd (Rth_ARth (SORsetoid sor) Rops_wd (SORrt sor))
                (SORrm addon).(* Check that a formula f is inconsistent by normalizing and comparing the
resulting constant with 0 *)

Definition check_inconsistent (f : NFormula) : bool :=
let (e, op) := f in
  match  e with
  | Pc c =>
    match op with
    | Equal => cneqb c cO
    | NonStrict => c [<] cO
    | Strict => c [<=] cO
    | NonEqual => c [=] cO
    end
  | _ => false (* not a constant *)
  end.

Lemma check_inconsistent_sound : forall (p : PolC) (op : Op1), check_inconsistent (p, op) = true -> forall env, ~ eval_op1 op (eval_pol env p).