Proof using.
intros.
eapply deduplicate_log'_snoc_split; eauto.
intros. simpl in *. congruence.
Qed.

(* Specifications: *)
Lemma execute_log_app :
forall xs ys,
execute_log (xs ++ ys) = let (tr, st) := execute_log xs in execute_log' ys st tr.