Theorem ExactMinusInterval : forall P, RoundedModeP b radix P -> forall p q : float, (0 <= p)%R -> (p <= q)%R -> Fbounded b p -> Fbounded b q -> (exists r : float, Fbounded b r /\ r = (q - p)%R :>R) -> forall r : float, Fbounded b r -> (p <= r)%R -> (r <= q)%R -> exists r' : float, Fbounded b r' /\ r' = (r - p)%R :>R.