- parallel substitution reaxiomatized

[helm.git] / matita / matita / contribs / lambdadelta / basic_2 / unfold / lcpss_lcpss.ma

diff --git a/matita/matita/contribs/lambdadelta/basic_2/unfold/lcpss_lcpss.ma b/matita/matita/contribs/lambdadelta/basic_2/unfold/lcpss_lcpss.ma
new file mode 100644 (file)
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+(**************************************************************************)
+(*       ___                                                              *)
+(*      ||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/unfold/lcpss_cpss.ma".
+
+(* SN PARALLEL UNFOLD ON LOCAL ENVIRONMENTS *********************************)
+
+(* Main properties **********************************************************)
+
+theorem lcpss_conf: confluent … lcpss.
+#L0 @(f_ind … length … L0) -L0 #n #IH *
+[ #_ #X1 #H1 #X2 #H2 -n
+  >(lcpss_inv_atom1 … H1) -X1
+  >(lcpss_inv_atom1 … H2) -X2 /2 width=3/
+| #L0 #I #V0 #Hn #X1 #H1 #X2 #H2 destruct
+  elim (lcpss_inv_pair1 … H1) -H1 #L1 #V1 #HL01 #HV01 #H destruct
+  elim (lcpss_inv_pair1 … H2) -H2 #L2 #V2 #HL02 #HV02 #H destruct
+  elim (IH … HL01 … HL02) -IH normalize // #L #HL1 #HL2
+  elim (cpss_conf_lcpss … HV01 … HV02 … HL01 … HL02) -L0 -V0 /3 width=5/
+]
+qed-.
+
+theorem lcpss_trans: Transitive … lcpss.
+#L1 #L #H elim H -L1 -L //
+#I #L1 #L #V1 #V #HL1 #HV1 #IHL1 #X #H
+elim (lcpss_inv_pair1 … H) -H #L2 #V2 #HL2 #HV2 #H destruct
+lapply (cpss_trans_lcpss … HV1 … HL1 … HV2) -V -HL1 /3 width=1/
+qed-.
+
+(* Advanced forward lemmas **************************************************)
+
+lemma cpss_fwd_shift1: ∀L1,L,T1,T. L ⊢ L1 @@ T1 ▶* T →
+                       ∃∃L2,T2. L @@ L1 ⊢ ▶* L @@ L2 & L @@ L1 ⊢ T1 ▶* T2 &
+                                T = L2 @@ T2.
+#L1 @(lenv_ind_dx … L1) -L1
+[ #L #T1 #T #HT1
+  @ex3_2_intro [3: // |4,5: // |1,2: skip ] (**) (* /2 width=4/ does not work *)
+| #I #L1 #V1 #IH #L #T1 #T >shift_append_assoc #H <append_assoc
+  elim (cpss_inv_bind1 … H) -H #V2 #T2 #HV12 #HT12 #H destruct
+  elim (IH … HT12) -IH -HT12 #L2 #T #HL12 #HT1 #H destruct
+  lapply (lcpss_trans … HL12 (L.ⓑ{I}V2@@L2) ?) -HL12 /3 width=1/ #HL12
+  @(ex3_2_intro … (⋆.ⓑ{I}V2@@L2)) [4: /2 width=3/ | skip ] <append_assoc // (**) (* explicit constructor *)
+]
+qed-.