Proof with eauto with val_renamings.
intros v v' v'' f f' f'' Hval'' Hval' Hf.
inversion Hval'; subst; inversion Hval''; subst...
Qed.

Lemma val_obs_list_incr:
forall (vs vs' : seq val) (f f' : memren),
val_obs_list f vs vs' ->
ren_incr f f' ->
val_obs_list f' vs vs'.