End RELSEM.
(** Execution of whole programs are described as sequences of transitions from an initial state to a final state.  An initial state is a [Callstate] corresponding to the invocation of the ``main'' function of the program without arguments and with an empty call stack. *)
Inductive initial_state (p: program): state -> Prop :=
| initial_state_intro: forall b f m0,
let ge := Genv.globalenv p in
Genv.init_mem p = Some m0 ->
Genv.find_symbol ge p.(prog_main) = Some b ->
Genv.find_funct_ptr ge b = Some f ->
funsig f = signature_main ->
initial_state p (Callstate nil f nil m0).
(** A final state is a [Returnstate] with an empty call stack. *)
Inductive final_state: state -> int -> Prop :=
| final_state_intro: forall r m,
final_state (Returnstate nil (Vint r) m) r.
(** The small-step semantics for a program. *)
Definition semantics (p: program) :=
Semantics step (initial_state p) final_state (Genv.globalenv p).
(** This semantics is receptive to changes in events. *)

(* Specifications: *)
Lemma semantics_receptive:
forall (p: program), receptive (semantics p).