update in static_2 and app_2

[helm.git] / matita / matita / contribs / lambdadelta / apps_2 / etc / models / vdrop_vlift.etc

diff --git a/matita/matita/contribs/lambdadelta/apps_2/etc/models/vdrop_vlift.etc b/matita/matita/contribs/lambdadelta/apps_2/etc/models/vdrop_vlift.etc
new file mode 100644 (file)
index 0000000..0316fa1
--- /dev/null
+++ b/matita/matita/contribs/lambdadelta/apps_2/etc/models/vdrop_vlift.etc
@@ -0,0 +1,29 @@
+(**************************************************************************)
+(*       ___                                                              *)
+(*      ||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 "apps_2/models/model_vlift.ma".
+include "apps_2/models/vdrop.ma".
+
+(* EVALUATION DROP **********************************************************)
+
+(* Advanced properties with evaluation evaluation lift **********************)
+
+lemma vlift_vdrop_eq (M): ∀lv,i. lv ≐{?,dd M} ⫯[i←lv i]⫰[i]lv.
+#M #lv #i #j elim (lt_or_eq_or_gt j i) #Hji destruct
+[ >vlift_lt // >vdrop_lt //
+| >vlift_eq //
+| >vlift_gt // >vdrop_ge /2 width=1 by monotonic_pred/
+  <(lt_succ_pred … Hji) //
+]
+qed.