Proof with eauto with val_renamings.
intros;
destruct v; inversion Hobs; subst; simpl...
Qed.

(* Specifications: *)
Lemma val_obs_longofint:
forall f v v'
(Hobs: val_obs f v v'),
val_obs f (Val.longofint v) (Val.longofint v').
Lemma val_obs_singleoffloat:
forall f v v'
(Hval_obs: val_obs f v v'),
val_obs f (Val.singleoffloat v) (Val.singleoffloat v').