Class Monotone_exp :=
  monotone_exp : forall ex ey, (ex <= ey)%Z -> (fexp ex <= fexp ey)%Z.Class Monotone_exp :=
  monotone_exp : forall ex ey, (ex <= ey)%Z -> (fexp ex <= fexp ey)%Z.Global Instance monotone_exp_not_FTZ : Exp_not_FTZ.

Lemma canonic_exp_ge_bpow : forall (x : R) (e : Z), (bpow (e - 1) <= Rabs x)%R -> (fexp e <= canonic_exp x)%Z.