Merge branch 'matita-lablgtk3' of ssh://matita.cs.unibo.it:/srv/git/helm into matita...

[helm.git] / matita / matita / contribs / lambdadelta / basic_2 / rt_transition / cpr_tdeq.ma

diff --git a/matita/matita/contribs/lambdadelta/basic_2/rt_transition/cpr_tdeq.ma b/matita/matita/contribs/lambdadelta/basic_2/rt_transition/cpr_tdeq.ma
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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 "static_2/relocation/lifts_tdeq.ma".
+include "basic_2/rt_transition/cpr_drops_basic.ma".
+
+(* CONTEXT-SENSITIVE PARALLEL R-TRANSITION FOR TERMS ************************)
+
+(* Properties with context-free sort-irrelevant equivalence *****************)
+
+lemma cpr_abbr_pos_tdneq (h) (G) (L) (V) (T1):
+      ∃∃T2. ⦃G,L⦄ ⊢ +ⓓV.T1 ➡[h] T2 & (+ⓓV.T1 ≛ T2 → ⊥).
+#h #G #L #V #U1
+elim (cpr_subst h G (L.ⓓV) U1 … 0) [|*: /2 width=4 by drops_refl/ ] #U2 #T2 #HU12 #HTU2
+elim (tdeq_dec U1 U2) [ -HU12 #HU12 | -HTU2 #HnU12 ]
+[ elim (tdeq_inv_lifts_dx … HU12 … HTU2) -U2 #T1 #HTU1 #_ -T2
+  /3 width=9 by cpm_zeta, tdeq_lifts_inv_pair_sn, ex2_intro/
+| @(ex2_intro … (+ⓓV.U2)) [ /2 width=1 by cpm_bind/ ] -HU12 #H
+  elim (tdeq_inv_pair … H) -H #_ #_ /2 width=1 by/
+]
+qed-.