(** ** Transitions preserve semantics *)

(** We define the semantics of states as follows.
  For a triple [mu, sigma, tau], we perform the moves [tau] in
  reverse sequential order, then the moves [mu ++ sigma] in parallel. *)

Definition statemove (st: state) (e: env) :=
  match st with
  | State mu sigma tau => exec_par (mu ++ sigma) (exec_seq_rev tau e)
  end.

Lemma exec_par_update_no_read: forall s d m e, no_read m d -> ~In d (dests m) -> exec_par m (update d (e s) e) = update d (e s) (exec_par m e).