Proof with auto with typeclass_instances.
intros x d Fd (Hxd1,Hxd2).
generalize (round_DN_pt beta fexp x); intros (T1,(T2,T3)).
apply sym_eq, Rle_antisym.
now apply T3.
destruct (generic_format_EM beta fexp x) as [Fx|NFx].
rewrite round_generic...
apply succ_le_inv; try assumption.
apply succ_le_lt; try assumption.
apply generic_format_succ...
apply succ_le_inv; try assumption.
rewrite succ_DN_eq_UP; trivial.
apply round_UP_pt...
apply generic_format_succ...
now left.
Qed.

(* Specifications: *)
(* was betw_eq_UP *)
Theorem round_UP_eq_betw: forall x u, F u
-> (pred u < x <= u)%R
-> round beta fexp Zceil x = u.