(* * Copyright (c) 2009 Robert Dockins and Aquinas Hobor. * *)
(* Coq development: using indirection theory to model types in l-calculus *)
(** Redex rules **)

Lemma typ_beta: forall v1 v2 sigma tau w,
forces w v1 (ty_lam sigma tau) ->
forces w v2 (%sigma) ->
forall v', expr_type (App (val_to_exp v1) (val_to_exp v2)) tau (w,v').