update in delayed_updating

[helm.git] / matita / matita / contribs / lambdadelta / delayed_updating / substitution / fsubst_lift.ma

diff --git a/matita/matita/contribs/lambdadelta/delayed_updating/substitution/fsubst_lift.ma b/matita/matita/contribs/lambdadelta/delayed_updating/substitution/fsubst_lift.ma
new file mode 100644 (file)
index 0000000..c9d6560
--- /dev/null
+++ b/matita/matita/contribs/lambdadelta/delayed_updating/substitution/fsubst_lift.ma
@@ -0,0 +1,56 @@
+(**************************************************************************)
+(*       ___                                                              *)
+(*      ||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 "delayed_updating/substitution/fsubst.ma".
+include "delayed_updating/substitution/lift_prototerm.ma".
+include "delayed_updating/substitution/lift_structure.ma".
+include "delayed_updating/syntax/preterm.ma".
+include "delayed_updating/syntax/prototerm_proper.ma".
+
+(* FOCALIZED SUBSTITUTION ***************************************************)
+
+lemma lift_fsubst_sn (f) (t) (u) (p): Ꝕu → p ⧸ϵ t →
+      (↑[f]t)[⋔(⊗p)←↑[↑[p]f]u] ⊆ ↑[f](t[⋔p←u]).
+#f #t #u #p #Hu #Hp #ql * *
+[ #rl * #r #Hr #H1 #H2 destruct
+  >lift_append_proper_dx
+  /4 width=1 by subset_in_ext_f1_dx, or_introl/
+| * #q #Hq #H1 #H0
+  @(ex2_intro … H1) @or_intror @conj //
+  #r #H2 destruct
+  @H0 -H0 [| <lift_append_proper_dx /2 width=1 by/ ]
+]
+qed-.
+
+lemma lift_fsubst_dx (f) (t) (u) (p): Ꝕu → p ϵ ▵t → structure_injective t →
+      ↑[f](t[⋔p←u]) ⊆ (↑[f]t)[⋔(⊗p)←↑[↑[p]f]u].
+#f #t #u #p #Hu #H1p #H2p #ql * #q * *
+[ #r #Hu #H1 #H2 destruct
+  @or_introl @ex2_intro
+  [|| <lift_append_proper_dx /2 width=1 by/ ]
+  /2 width=3 by ex2_intro/
+| #Hq #H0 #H1 destruct
+  @or_intror @conj [ /2 width=1 by subset_in_ext_f1_dx/ ] *
+  [ <list_append_empty_dx #Hr @(H0 … (𝐞)) -H0
+    <list_append_empty_dx @H2p -H2p /2 width=1 by prototerm_in_comp_root/
+  | #l #r #Hr
+    elim (lift_inv_append_proper_dx … Hr) -Hr // #s1 #s2 #Hs1 #_ #H1 destruct
+    lapply (H2p … Hs1) -H2p -Hs1 /2 width=2 by ex_intro/
+  ]
+]
+qed-.
+
+lemma lift_fsubst (f) (t) (u) (p): Ꝕu → p ⧸ϵ t → p ϵ ▵t → structure_injective t →
+      (↑[f]t)[⋔(⊗p)←↑[↑[p]f]u] ⇔ ↑[f](t[⋔p←u]).
+/4 width=3 by lift_fsubst_sn, conj, lift_fsubst_dx/ qed.