--- /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/s_computation/fqus_fqup.ma".
+include "basic_2/static/lfdeq_drops.ma".
+include "basic_2/static/lfdeq_lfdeq.ma".
+
+(* DEGREE-BASED EQUIVALENCE FOR LOCAL ENVIRONMENTS ON REFERRED ENTRIES ******)
+
+(* Properties with supclosure ***********************************************)
+
+lemma fqu_tdeq_conf: ∀h,o,G1,G2,L1,L2,U1,T1. ⦃G1, L1, U1⦄ ⊐ ⦃G2, L2, T1⦄ →
+ ∀U2. U1 ≡[h, o] U2 →
+ ∃∃L,T2. ⦃G1, L1, U2⦄ ⊐ ⦃G2, L, T2⦄ & L2 ≡[h, o, T1] L & T1 ≡[h, o] T2.
+#h #o #G1 #G2 #L1 #L2 #U1 #T1 #H elim H -G1 -G2 -L1 -L2 -U1 -T1
+[ #I #G #L #W #X #H >(tdeq_inv_lref1 … H) -H
+ /2 width=5 by fqu_lref_O, ex3_2_intro/
+| #I #G #L #W1 #U1 #X #H
+ elim (tdeq_inv_pair1 … H) -H #W2 #U2 #HW12 #_ #H destruct
+ /2 width=5 by fqu_pair_sn, ex3_2_intro/
+| #p #I #G #L #W1 #U1 #X #H
+ elim (tdeq_inv_pair1 … H) -H #W2 #U2 #HW12 #HU12 #H destruct
+ /3 width=5 by lfdeq_pair, fqu_bind_dx, ex3_2_intro/
+| #I #G #L #W1 #U1 #X #H
+ elim (tdeq_inv_pair1 … H) -H #W2 #U2 #_ #HU12 #H destruct
+ /2 width=5 by fqu_flat_dx, ex3_2_intro/
+| #I #G #L #W #T1 #U1 #HTU1 #U2 #HU12
+ elim (tdeq_inv_lifts … HU12 … HTU1) -U1 #T2 #HTU2 #HT12
+ /3 width=5 by fqu_drop, ex3_2_intro/
+]
+qed-.
+
+lemma tdeq_fqu_trans: ∀h,o,G1,G2,L1,L2,U1,T1. ⦃G1, L1, U1⦄ ⊐ ⦃G2, L2, T1⦄ →
+ ∀U2. U2 ≡[h, o] U1 →
+ ∃∃L,T2. ⦃G1, L1, U2⦄ ⊐ ⦃G2, L, T2⦄ & T2 ≡[h, o] T1 & L ≡[h, o, T1] L2.
+#h #o #G1 #G2 #L1 #L2 #U1 #T1 #H12 #U2 #HU21
+elim (fqu_tdeq_conf … o … H12 U2) -H12
+/3 width=5 by lfdeq_sym, tdeq_sym, ex3_2_intro/
+qed-.
+
+(* Basic_2A1: was just: lleq_fqu_trans *)
+lemma lfdeq_fqu_trans: ∀h,o,G1,G2,L2,K2,T,U. ⦃G1, L2, T⦄ ⊐ ⦃G2, K2, U⦄ →
+ ∀L1. L1 ≡[h, o, T] L2 →
+ ∃∃K1,U0. ⦃G1, L1, T⦄ ⊐ ⦃G2, K1, U0⦄ & U0 ≡[h, o] U & K1 ≡[h, o, U] K2.
+#h #o #G1 #G2 #L2 #K2 #T #U #H elim H -G1 -G2 -L2 -K2 -T -U
+[ #I #G #L2 #V2 #L1 #H elim (lfdeq_inv_zero_pair_dx … H) -H
+ #K1 #V1 #HV1 #HV12 #H destruct
+ /3 width=7 by tdeq_lfdeq_conf_sn, fqu_lref_O, ex3_2_intro/
+| * [ #p ] #I #G #L2 #V #T #L1 #H
+ [ elim (lfdeq_inv_bind … H)
+ | elim (lfdeq_inv_flat … H)
+ ] -H
+ /2 width=5 by fqu_pair_sn, ex3_2_intro/
+| #a #I #G #L2 #V #T #L1 #H elim (lfdeq_inv_bind … H) -H
+ /2 width=5 by fqu_bind_dx, ex3_2_intro/
+| #I #G #L2 #V #T #L1 #H elim (lfdeq_inv_flat … H) -H
+ /2 width=5 by fqu_flat_dx, ex3_2_intro/
+| #I #G #L2 #V2 #T #U #HTU #Y #HU
+ elim (lfdeq_fwd_dx … HU) #L1 #V1 #H destruct
+ /5 width=12 by lfdeq_inv_lifts_bi, fqu_drop, drops_refl, drops_drop, ex3_2_intro/
+]
+qed-.
+
+(* Basic_2A1: was just: lleq_fquq_trans *)
+lemma lfdeq_fquq_trans: ∀h,o,G1,G2,L2,K2,T,U. ⦃G1, L2, T⦄ ⊐⸮ ⦃G2, K2, U⦄ →
+ ∀L1. L1 ≡[h, o, T] L2 →
+ ∃∃K1,U0. ⦃G1, L1, T⦄ ⊐⸮ ⦃G2, K1, U0⦄ & U0 ≡[h, o] U & K1 ≡[h, o, U] K2.
+#h #o #G1 #G2 #L2 #K2 #T #U #H elim H -H
+[ #H #L1 #HL12 elim (lfdeq_fqu_trans … H … HL12) -L2 /3 width=5 by fqu_fquq, ex3_2_intro/
+| * #HG #HL #HT destruct /2 width=5 by ex3_2_intro/
+]
+qed-.
+
+(* Basic_2A1: was just: lleq_fqup_trans *)
+lemma lfdeq_fqup_trans: ∀h,o,G1,G2,L2,K2,T,U. ⦃G1, L2, T⦄ ⊐+ ⦃G2, K2, U⦄ →
+ ∀L1. L1 ≡[h, o, T] L2 →
+ ∃∃K1,U0. ⦃G1, L1, T⦄ ⊐+ ⦃G2, K1, U0⦄ & U0 ≡[h, o] U & K1 ≡[h, o, U] K2.
+#h #o #G1 #G2 #L2 #K2 #T #U #H @(fqup_ind … H) -G2 -K2 -U
+[ #G2 #K2 #U #HTU #L1 #HL12 elim (lfdeq_fqu_trans … HTU … HL12) -L2
+ /3 width=5 by fqu_fqup, ex3_2_intro/
+| #G #G2 #K #K2 #U #U2 #_ #HU2 #IHTU #L1 #HL12
+ elim (IHTU … HL12) -L2 #K0 #U0 #HTU #HU0 #HK0
+ elim (lfdeq_fqu_trans … HU2 … HK0) -K #K1 #U1 #HU1 #HU12 #HK12
+ elim (tdeq_fqu_trans … HU1 … HU0) -U #K3 #U3 #HU03 #HU31 #HK31
+ @(ex3_2_intro … K3 U3) (**) (* full auto too slow *)
+ /3 width=5 by lfdeq_trans, tdeq_lfdeq_conf_sn, fqup_strap1, tdeq_trans/
+]
+qed-.
+
+(* Basic_2A1: was just: lleq_fqus_trans *)
+lemma lfdeq_fqus_trans: ∀h,o,G1,G2,L2,K2,T,U. ⦃G1, L2, T⦄ ⊐* ⦃G2, K2, U⦄ →
+ ∀L1. L1 ≡[h, o, T] L2 →
+ ∃∃K1,U0. ⦃G1, L1, T⦄ ⊐* ⦃G2, K1, U0⦄ & U0 ≡[h, o] U & K1 ≡[h, o, U] K2.
+#h #o #G1 #G2 #L2 #K2 #T #U #H #L1 #HL12 elim(fqus_inv_fqup … H) -H
+[ #H elim (lfdeq_fqup_trans … H … HL12) -L2 /3 width=5 by fqup_fqus, ex3_2_intro/
+| * #HG #HL #HT destruct /2 width=5 by ex3_2_intro/
+]
+qed-.