--- /dev/null
+(**************************************************************************)
+(* ___ *)
+(* ||M|| *)
+(* ||A|| A project by Andrea Asperti *)
+(* ||T|| *)
+(* ||I|| Developers: *)
+(* ||T|| The HELM team. *)
+(* ||A|| http://helm.cs.unibo.it *)
+(* \ / *)
+(* \ / This file is distributed under the terms of the *)
+(* v GNU General Public License Version 2 *)
+(* *)
+(**************************************************************************)
+
+include "basic_2/rt_computation/cpms_drops.ma".
+include "basic_2/dynamic/cnv.ma".
+
+(* EXAMPLES *****************************************************************)
+
+(* Extended validy (basic?_2) vs. restricted validity (basic_1) *************)
+
+(* Note: extended validity of a closure, height of cnv_appl > 1 *)
+lemma cnv_extended (h) (p): ∀G,L,s. ⦃G, L.ⓛ⋆s.ⓛⓛ{p}⋆s.⋆s.ⓛ#0⦄ ⊢ ⓐ#2.#0 ![Ⓕ,h].
+#h #p #G #L #s
+@(cnv_appl … 2 p … (⋆s) … (⋆s))
+[ #H destruct
+| /4 width=1 by cnv_sort, cnv_zero, cnv_lref/
+| /4 width=1 by cnv_bind, cnv_zero/
+| /5 width=3 by cpm_cpms, cpm_lref, cpm_ell, lifts_sort/
+| /5 width=5 by cpm_cpms, cpm_bind, cpm_ell, lifts_uni, lifts_sort, lifts_bind/
+]
+qed.
+
+(* Note: restricted validity of the η-expanded closure, height of cnv_appl = 1 **)
+lemma vnv_restricted (h) (p): ∀G,L,s. ⦃G, L.ⓛ⋆s.ⓛⓛ{p}⋆s.⋆s.ⓛⓛ{p}⋆s.ⓐ#0.#1⦄ ⊢ ⓐ#2.#0 ![Ⓣ,h].
+#h #p #G #L #s
+@(cnv_appl … 1 p … (⋆s) … (ⓐ#0.#2))
+[ /2 width=1 by/
+| /4 width=1 by cnv_sort, cnv_zero, cnv_lref/
+| @cnv_zero
+ @cnv_bind //
+ @(cnv_appl … 1 p … (⋆s) … (⋆s))
+ [ /2 width=1 by/
+ | /2 width=1 by cnv_sort, cnv_zero/
+ | /4 width=1 by cnv_sort, cnv_zero, cnv_lref, cnv_bind/
+ | /2 width=3 by cpms_ell, lifts_sort/
+ | /4 width=5 by cpms_lref, cpms_ell, lifts_uni, lifts_sort, lifts_bind/
+ ]
+| /4 width=3 by cpms_lref, cpms_ell, lifts_sort/
+| /5 width=7 by cpms_ell, lifts_bind, lifts_flat, lifts_push_lref, lifts_push_zero, lifts_sort/
+]
+qed.