Definition Fulp (p : float) :=
  powerRZ radix (Fexp (Fnormalize radix b precision p)).

Theorem RoundLSBMax : forall (P : R -> float -> Prop) (p q : float), RoundedModeP b radix P -> P p q -> ~ is_Fzero q -> (LSB radix p <= LSB radix q)%Z.