(* * Copyright (c) 2009 Robert Dockins and Aquinas Hobor. * *)
(* Coq development: using indirection theory to model types in l-calculus *)
(* lam_ref_mach_lemmas.v: various boring lemmas about the machine *)
(* COERCIONS *)
(* DECIDABILTY *)
(* SUBSTITUTION *)
(* STEP RELATION *)

Lemma closed_subst_env : forall env e x n,
closed' (length env + x) e ->
closed' (x + n) (subst_env' (x + n) env e).