(** * Receptiveness and determinacy *)

Definition single_events (L: semantics) : Prop :=
  forall s t s', Step L s t s' -> (length t <= 1)%nat.Record receptive (L: semantics) : Prop :=
  Receptive {
    sr_receptive: forall s t1 s1 t2,
      Step L s t1 s1 -> match_traces (symbolenv L) t1 t2 -> exists s2, Step L s t2 s2;
    sr_traces:
      single_events L
  }.Record receptive (L: semantics) : Prop :=
  Receptive {
    sr_receptive: forall s t1 s1 t2,
      Step L s t1 s1 -> match_traces (symbolenv L) t1 t2 -> exists s2, Step L s t2 s2;
    sr_traces:
      single_events L
  }.Record receptive (L: semantics) : Prop :=
  Receptive {
    sr_receptive: forall s t1 s1 t2,
      Step L s t1 s1 -> match_traces (symbolenv L) t1 t2 -> exists s2, Step L s t2 s2;
    sr_traces:
      single_events L
  }.Record receptive (L: semantics) : Prop :=
  Receptive {
    sr_receptive: forall s t1 s1 t2,
      Step L s t1 s1 -> match_traces (symbolenv L) t1 t2 -> exists s2, Step L s t2 s2;
    sr_traces:
      single_events L
  }.Record determinate (L: semantics) : Prop :=
  Determinate {
    sd_determ: forall s t1 s1 t2 s2,
      Step L s t1 s1 -> Step L s t2 s2 ->
      match_traces (symbolenv L) t1 t2 /\ (t1 = t2 -> s1 = s2);
    sd_traces:
      single_events L;
    sd_initial_determ: forall s1 s2 f arg m0,
        start_stack L m0 s1 f arg -> start_stack L m0 s2 f arg ->
        s1 = s2;
    sd_final_nostep: forall s r,
      final_state L s r -> Nostep L s;
    sd_final_determ: forall s r1 r2,
      final_state L s r1 -> final_state L s r2 -> r1 = r2
  }.Record determinate (L: semantics) : Prop :=
  Determinate {
    sd_determ: forall s t1 s1 t2 s2,
      Step L s t1 s1 -> Step L s t2 s2 ->
      match_traces (symbolenv L) t1 t2 /\ (t1 = t2 -> s1 = s2);
    sd_traces:
      single_events L;
    sd_initial_determ: forall s1 s2 f arg m0,
        start_stack L m0 s1 f arg -> start_stack L m0 s2 f arg ->
        s1 = s2;
    sd_final_nostep: forall s r,
      final_state L s r -> Nostep L s;
    sd_final_determ: forall s r1 r2,
      final_state L s r1 -> final_state L s r2 -> r1 = r2
  }.Record determinate (L: semantics) : Prop :=
  Determinate {
    sd_determ: forall s t1 s1 t2 s2,
      Step L s t1 s1 -> Step L s t2 s2 ->
      match_traces (symbolenv L) t1 t2 /\ (t1 = t2 -> s1 = s2);
    sd_traces:
      single_events L;
    sd_initial_determ: forall s1 s2 f arg m0,
        start_stack L m0 s1 f arg -> start_stack L m0 s2 f arg ->
        s1 = s2;
    sd_final_nostep: forall s r,
      final_state L s r -> Nostep L s;
    sd_final_determ: forall s r1 r2,
      final_state L s r1 -> final_state L s r2 -> r1 = r2
  }.Record determinate (L: semantics) : Prop :=
  Determinate {
    sd_determ: forall s t1 s1 t2 s2,
      Step L s t1 s1 -> Step L s t2 s2 ->
      match_traces (symbolenv L) t1 t2 /\ (t1 = t2 -> s1 = s2);
    sd_traces:
      single_events L;
    sd_initial_determ: forall s1 s2 f arg m0,
        start_stack L m0 s1 f arg -> start_stack L m0 s2 f arg ->
        s1 = s2;
    sd_final_nostep: forall s r,
      final_state L s r -> Nostep L s;
    sd_final_determ: forall s r1 r2,
      final_state L s r1 -> final_state L s r2 -> r1 = r2
  }.Record determinate (L: semantics) : Prop :=
  Determinate {
    sd_determ: forall s t1 s1 t2 s2,
      Step L s t1 s1 -> Step L s t2 s2 ->
      match_traces (symbolenv L) t1 t2 /\ (t1 = t2 -> s1 = s2);
    sd_traces:
      single_events L;
    sd_initial_determ: forall s1 s2 f arg m0,
        start_stack L m0 s1 f arg -> start_stack L m0 s2 f arg ->
        s1 = s2;
    sd_final_nostep: forall s r,
      final_state L s r -> Nostep L s;
    sd_final_determ: forall s r1 r2,
      final_state L s r1 -> final_state L s r2 -> r1 = r2
  }.Record determinate (L: semantics) : Prop :=
  Determinate {
    sd_determ: forall s t1 s1 t2 s2,
      Step L s t1 s1 -> Step L s t2 s2 ->
      match_traces (symbolenv L) t1 t2 /\ (t1 = t2 -> s1 = s2);
    sd_traces:
      single_events L;
    sd_initial_determ: forall s1 s2 f arg m0,
        start_stack L m0 s1 f arg -> start_stack L m0 s2 f arg ->
        s1 = s2;
    sd_final_nostep: forall s r,
      final_state L s r -> Nostep L s;
    sd_final_determ: forall s r1 r2,
      final_state L s r1 -> final_state L s r2 -> r1 = r2
  }.Record determinate (L: semantics) : Prop :=
  Determinate {
    sd_determ: forall s t1 s1 t2 s2,
      Step L s t1 s1 -> Step L s t2 s2 ->
      match_traces (symbolenv L) t1 t2 /\ (t1 = t2 -> s1 = s2);
    sd_traces:
      single_events L;
    sd_initial_determ: forall s1 s2 f arg m0,
        start_stack L m0 s1 f arg -> start_stack L m0 s2 f arg ->
        s1 = s2;
    sd_final_nostep: forall s r,
      final_state L s r -> Nostep L s;
    sd_final_determ: forall s r1 r2,
      final_state L s r1 -> final_state L s r2 -> r1 = r2
  }.

Lemma star_determinacy: forall s t s', Star L s t s' -> forall s'', Star L s t s'' -> Star L s' E0 s'' \/ Star L s'' E0 s'.