(* OUT-OF-SCOPE *)

(* xistential rework - dummy step *)
Definition step_fun (t : tm) : option tm := Some t.Axiom step_fun_correct : forall t t',
    step_fun t = Some t' <-> step t t'.Instance dec_step (t : tm) : Dec (exists t', step t t') :=
  {| dec := _ |}.

(* Specifications: *)
Theorem strong_progress : forall t, value t \/ (exists t', t ===> t').