--- /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/notation/relations/stareqsn_5.ma".
+include "basic_2/syntax/tdeq_ext.ma".
+include "basic_2/static/rex.ma".
+
+(* DEGREE-BASED EQUIVALENCE FOR LOCAL ENVIRONMENTS ON REFERRED ENTRIES ******)
+
+definition rdeq (h) (o): relation3 term lenv lenv โ
+ rex (cdeq h o).
+
+interpretation
+ "degree-based equivalence on referred entries (local environment)"
+ 'StarEqSn h o T L1 L2 = (rdeq h o T L1 L2).
+
+interpretation
+ "degree-based ranged equivalence (local environment)"
+ 'StarEqSn h o f L1 L2 = (sex (cdeq_ext h o) cfull f L1 L2).
+
+(* Basic properties ***********************************************************)
+
+lemma frees_tdeq_conf_rdeq (h) (o): โf,L1,T1. L1 โข ๐
*โฆT1โฆ โ f โ โT2. T1 โ[h, o] T2 โ
+ โL2. L1 โ[h, o, f] L2 โ L2 โข ๐
*โฆT2โฆ โ f.
+#h #o #f #L1 #T1 #H elim H -f -L1 -T1
+[ #f #L1 #s1 #Hf #X #H1 #L2 #_
+ elim (tdeq_inv_sort1 โฆ H1) -H1 #s2 #d #_ #_ #H destruct
+ /2 width=3 by frees_sort/
+| #f #i #Hf #X #H1
+ >(tdeq_inv_lref1 โฆ H1) -X #Y #H2
+ >(sex_inv_atom1 โฆ H2) -Y
+ /2 width=1 by frees_atom/
+| #f #I #L1 #V1 #_ #IH #X #H1
+ >(tdeq_inv_lref1 โฆ H1) -X #Y #H2
+ elim (sex_inv_next1 โฆ H2) -H2 #Z #L2 #HL12 #HZ #H destruct
+ elim (ext2_inv_pair_sn โฆ HZ) -HZ #V2 #HV12 #H destruct
+ /3 width=1 by frees_pair/
+| #f #I #L1 #Hf #X #H1
+ >(tdeq_inv_lref1 โฆ H1) -X #Y #H2
+ elim (sex_inv_next1 โฆ H2) -H2 #Z #L2 #_ #HZ #H destruct
+ >(ext2_inv_unit_sn โฆ HZ) -Z /2 width=1 by frees_unit/
+| #f #I #L1 #i #_ #IH #X #H1
+ >(tdeq_inv_lref1 โฆ H1) -X #Y #H2
+ elim (sex_inv_push1 โฆ H2) -H2 #J #L2 #HL12 #_ #H destruct
+ /3 width=1 by frees_lref/
+| #f #L1 #l #Hf #X #H1 #L2 #_
+ >(tdeq_inv_gref1 โฆ H1) -X /2 width=1 by frees_gref/
+| #f1V #f1T #f1 #p #I #L1 #V1 #T1 #_ #_ #Hf1 #IHV #IHT #X #H1
+ elim (tdeq_inv_pair1 โฆ H1) -H1 #V2 #T2 #HV12 #HT12 #H1 #L2 #HL12 destruct
+ /6 width=5 by frees_bind, sex_inv_tl, ext2_pair, sle_sex_trans, sor_inv_sle_dx, sor_inv_sle_sn/
+| #f1V #f1T #f1 #I #L1 #V1 #T1 #_ #_ #Hf1 #IHV #IHT #X #H1
+ elim (tdeq_inv_pair1 โฆ H1) -H1 #V2 #T2 #HV12 #HT12 #H1 #L2 #HL12 destruct
+ /5 width=5 by frees_flat, sle_sex_trans, sor_inv_sle_dx, sor_inv_sle_sn/
+]
+qed-.
+
+lemma frees_tdeq_conf (h) (o): โf,L,T1. L โข ๐
*โฆT1โฆ โ f โ
+ โT2. T1 โ[h, o] T2 โ L โข ๐
*โฆT2โฆ โ f.
+/4 width=7 by frees_tdeq_conf_rdeq, sex_refl, ext2_refl/ qed-.
+
+lemma frees_rdeq_conf (h) (o): โf,L1,T. L1 โข ๐
*โฆTโฆ โ f โ
+ โL2. L1 โ[h, o, f] L2 โ L2 โข ๐
*โฆTโฆ โ f.
+/2 width=7 by frees_tdeq_conf_rdeq, tdeq_refl/ qed-.
+
+lemma tdeq_rex_conf (R) (h) (o): s_r_confluent1 โฆ (cdeq h o) (rex R).
+#R #h #o #L1 #T1 #T2 #HT12 #L2 *
+/3 width=5 by frees_tdeq_conf, ex2_intro/
+qed-.
+
+lemma tdeq_rex_div (R) (h) (o): โT1,T2. T1 โ[h, o] T2 โ
+ โL1,L2. L1 โชค[R, T2] L2 โ L1 โชค[R, T1] L2.
+/3 width=5 by tdeq_rex_conf, tdeq_sym/ qed-.
+
+lemma tdeq_rdeq_conf (h) (o): s_r_confluent1 โฆ (cdeq h o) (rdeq h o).
+/2 width=5 by tdeq_rex_conf/ qed-.
+
+lemma tdeq_rdeq_div (h) (o): โT1,T2. T1 โ[h, o] T2 โ
+ โL1,L2. L1 โ[h, o, T2] L2 โ L1 โ[h, o, T1] L2.
+/2 width=5 by tdeq_rex_div/ qed-.
+
+lemma rdeq_atom (h) (o): โI. โ โ[h, o, โช{I}] โ.
+/2 width=1 by rex_atom/ qed.
+
+lemma rdeq_sort (h) (o): โI1,I2,L1,L2,s.
+ L1 โ[h, o, โs] L2 โ L1.โ{I1} โ[h, o, โs] L2.โ{I2}.
+/2 width=1 by rex_sort/ qed.
+
+lemma rdeq_pair (h) (o): โI,L1,L2,V1,V2. L1 โ[h, o, V1] L2 โ V1 โ[h, o] V2 โ
+ L1.โ{I}V1 โ[h, o, #0] L2.โ{I}V2.
+/2 width=1 by rex_pair/ qed.
+(*
+lemma rdeq_unit (h) (o): โf,I,L1,L2. ๐โฆfโฆ โ L1 โชค[cdeq_ext h o, cfull, f] L2 โ
+ L1.โค{I} โ[h, o, #0] L2.โค{I}.
+/2 width=3 by rex_unit/ qed.
+*)
+lemma rdeq_lref (h) (o): โI1,I2,L1,L2,i.
+ L1 โ[h, o, #i] L2 โ L1.โ{I1} โ[h, o, #โi] L2.โ{I2}.
+/2 width=1 by rex_lref/ qed.
+
+lemma rdeq_gref (h) (o): โI1,I2,L1,L2,l.
+ L1 โ[h, o, ยงl] L2 โ L1.โ{I1} โ[h, o, ยงl] L2.โ{I2}.
+/2 width=1 by rex_gref/ qed.
+
+lemma rdeq_bind_repl_dx (h) (o): โI,I1,L1,L2.โT:term.
+ L1.โ{I} โ[h, o, T] L2.โ{I1} โ
+ โI2. I โ[h, o] I2 โ
+ L1.โ{I} โ[h, o, T] L2.โ{I2}.
+/2 width=2 by rex_bind_repl_dx/ qed-.
+
+(* Basic inversion lemmas ***************************************************)
+
+lemma rdeq_inv_atom_sn (h) (o): โY2. โT:term. โ โ[h, o, T] Y2 โ Y2 = โ.
+/2 width=3 by rex_inv_atom_sn/ qed-.
+
+lemma rdeq_inv_atom_dx (h) (o): โY1. โT:term. Y1 โ[h, o, T] โ โ Y1 = โ.
+/2 width=3 by rex_inv_atom_dx/ qed-.
+(*
+lemma rdeq_inv_zero (h) (o): โY1,Y2. Y1 โ[h, o, #0] Y2 โ
+ โจโจ โงโง Y1 = โ & Y2 = โ
+ | โโI,L1,L2,V1,V2. L1 โ[h, o, V1] L2 & V1 โ[h, o] V2 &
+ Y1 = L1.โ{I}V1 & Y2 = L2.โ{I}V2
+ | โโf,I,L1,L2. ๐โฆfโฆ & L1 โชค[cdeq_ext h o, cfull, f] L2 &
+ Y1 = L1.โค{I} & Y2 = L2.โค{I}.
+#h #o #Y1 #Y2 #H elim (rex_inv_zero โฆ H) -H *
+/3 width=9 by or3_intro0, or3_intro1, or3_intro2, ex4_5_intro, ex4_4_intro, conj/
+qed-.
+*)
+lemma rdeq_inv_lref (h) (o): โY1,Y2,i. Y1 โ[h, o, #โi] Y2 โ
+ โจโจ โงโง Y1 = โ & Y2 = โ
+ | โโI1,I2,L1,L2. L1 โ[h, o, #i] L2 &
+ Y1 = L1.โ{I1} & Y2 = L2.โ{I2}.
+/2 width=1 by rex_inv_lref/ qed-.
+
+(* Basic_2A1: uses: lleq_inv_bind lleq_inv_bind_O *)
+lemma rdeq_inv_bind (h) (o): โp,I,L1,L2,V,T. L1 โ[h, o, โ{p,I}V.T] L2 โ
+ โงโง L1 โ[h, o, V] L2 & L1.โ{I}V โ[h, o, T] L2.โ{I}V.
+/2 width=2 by rex_inv_bind/ qed-.
+
+(* Basic_2A1: uses: lleq_inv_flat *)
+lemma rdeq_inv_flat (h) (o): โI,L1,L2,V,T. L1 โ[h, o, โ{I}V.T] L2 โ
+ โงโง L1 โ[h, o, V] L2 & L1 โ[h, o, T] L2.
+/2 width=2 by rex_inv_flat/ qed-.
+
+(* Advanced inversion lemmas ************************************************)
+
+lemma rdeq_inv_zero_pair_sn (h) (o): โI,Y2,L1,V1. L1.โ{I}V1 โ[h, o, #0] Y2 โ
+ โโL2,V2. L1 โ[h, o, V1] L2 & V1 โ[h, o] V2 & Y2 = L2.โ{I}V2.
+/2 width=1 by rex_inv_zero_pair_sn/ qed-.
+
+lemma rdeq_inv_zero_pair_dx (h) (o): โI,Y1,L2,V2. Y1 โ[h, o, #0] L2.โ{I}V2 โ
+ โโL1,V1. L1 โ[h, o, V1] L2 & V1 โ[h, o] V2 & Y1 = L1.โ{I}V1.
+/2 width=1 by rex_inv_zero_pair_dx/ qed-.
+
+lemma rdeq_inv_lref_bind_sn (h) (o): โI1,Y2,L1,i. L1.โ{I1} โ[h, o, #โi] Y2 โ
+ โโI2,L2. L1 โ[h, o, #i] L2 & Y2 = L2.โ{I2}.
+/2 width=2 by rex_inv_lref_bind_sn/ qed-.
+
+lemma rdeq_inv_lref_bind_dx (h) (o): โI2,Y1,L2,i. Y1 โ[h, o, #โi] L2.โ{I2} โ
+ โโI1,L1. L1 โ[h, o, #i] L2 & Y1 = L1.โ{I1}.
+/2 width=2 by rex_inv_lref_bind_dx/ qed-.
+
+(* Basic forward lemmas *****************************************************)
+
+lemma rdeq_fwd_zero_pair (h) (o): โI,K1,K2,V1,V2.
+ K1.โ{I}V1 โ[h, o, #0] K2.โ{I}V2 โ K1 โ[h, o, V1] K2.
+/2 width=3 by rex_fwd_zero_pair/ qed-.
+
+(* Basic_2A1: uses: lleq_fwd_bind_sn lleq_fwd_flat_sn *)
+lemma rdeq_fwd_pair_sn (h) (o): โI,L1,L2,V,T. L1 โ[h, o, โก{I}V.T] L2 โ L1 โ[h, o, V] L2.
+/2 width=3 by rex_fwd_pair_sn/ qed-.
+
+(* Basic_2A1: uses: lleq_fwd_bind_dx lleq_fwd_bind_O_dx *)
+lemma rdeq_fwd_bind_dx (h) (o): โp,I,L1,L2,V,T.
+ L1 โ[h, o, โ{p,I}V.T] L2 โ L1.โ{I}V โ[h, o, T] L2.โ{I}V.
+/2 width=2 by rex_fwd_bind_dx/ qed-.
+
+(* Basic_2A1: uses: lleq_fwd_flat_dx *)
+lemma rdeq_fwd_flat_dx (h) (o): โI,L1,L2,V,T. L1 โ[h, o, โ{I}V.T] L2 โ L1 โ[h, o, T] L2.
+/2 width=3 by rex_fwd_flat_dx/ qed-.
+
+lemma rdeq_fwd_dx (h) (o): โI2,L1,K2. โT:term. L1 โ[h, o, T] K2.โ{I2} โ
+ โโI1,K1. L1 = K1.โ{I1}.
+/2 width=5 by rex_fwd_dx/ qed-.
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