(* ----------------- nom_envsubst reductions ------------------- *)
(* We can think of a an environment as a multi-substitution for locally nameless terms.  Therefore, the nom_envsubst function inherits many of the properties of the subst_exp function.  *)

Lemma nom_envsubst_abs : forall rho e,
nom_envsubst rho (abs e) = abs (nom_envsubst rho e).