--- /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/lazyeq_3.ma".
+include "basic_2/grammar/ceq.ma".
+include "basic_2/relocation/lexs.ma".
+
+(* RANGED EQUIVALENCE FOR LOCAL ENVIRONMENTS ********************************)
+
+(* Basic_2A1: includes: lreq_atom lreq_zero lreq_pair lreq_succ *)
+definition lreq: relation3 rtmap lenv lenv ≝ lexs ceq cfull.
+
+interpretation
+ "ranged equivalence (local environment)"
+ 'LazyEq f L1 L2 = (lreq f L1 L2).
+
+(* Basic properties *********************************************************)
+
+lemma lreq_eq_repl_back: ∀L1,L2. eq_stream_repl_back … (λf. L1 ≡[f] L2).
+/2 width=3 by lexs_eq_repl_back/ qed-.
+
+lemma lreq_eq_repl_fwd: ∀L1,L2. eq_stream_repl_fwd … (λf. L1 ≡[f] L2).
+/2 width=3 by lexs_eq_repl_fwd/ qed-.
+
+lemma sle_lreq_trans: ∀L1,L2,f2. L1 ≡[f2] L2 →
+ ∀f1. f1 ⊆ f2 → L1 ≡[f1] L2.
+/2 width=3 by sle_lexs_trans/ qed-.
+
+(* Basic_2A1: includes: lreq_refl *)
+lemma lreq_refl: ∀f. reflexive … (lreq f).
+/2 width=1 by lexs_refl/ qed.
+
+(* Basic_2A1: includes: lreq_sym *)
+lemma lreq_sym: ∀f. symmetric … (lreq f).
+#f #L1 #L2 #H elim H -L1 -L2 -f
+/2 width=1 by lexs_next, lexs_push/
+qed-.
+
+(* Basic inversion lemmas ***************************************************)
+
+(* Basic_2A1: includes: lreq_inv_atom1 *)
+lemma lreq_inv_atom1: ∀Y,f. ⋆ ≡[f] Y → Y = ⋆.
+/2 width=4 by lexs_inv_atom1/ qed-.
+
+(* Basic_2A1: includes: lreq_inv_pair1 *)
+lemma lreq_inv_next1: ∀J,K1,Y,W1,g. K1.ⓑ{J}W1 ≡[⫯g] Y →
+ ∃∃K2. K1 ≡[g] K2 & Y = K2.ⓑ{J}W1.
+#J #K1 #Y #W1 #g #H elim (lexs_inv_next1 … H) -H /2 width=3 by ex2_intro/
+qed-.
+
+(* Basic_2A1: includes: lreq_inv_zero1 lreq_inv_succ1 *)
+lemma lreq_inv_push1: ∀J,K1,Y,W1,g. K1.ⓑ{J}W1 ≡[↑g] Y →
+ ∃∃K2,W2. K1 ≡[g] K2 & Y = K2.ⓑ{J}W2.
+#J #K1 #Y #W1 #g #H elim (lexs_inv_push1 … H) -H /2 width=4 by ex2_2_intro/ qed-.
+
+(* Basic_2A1: includes: lreq_inv_atom2 *)
+lemma lreq_inv_atom2: ∀X,f. X ≡[f] ⋆ → X = ⋆.
+/2 width=4 by lexs_inv_atom2/ qed-.
+
+(* Basic_2A1: includes: lreq_inv_pair2 *)
+lemma lreq_inv_next2: ∀J,X,K2,W2,g. X ≡[⫯g] K2.ⓑ{J}W2 →
+ ∃∃K1. K1 ≡[g] K2 & X = K1.ⓑ{J}W2.
+#J #X #K2 #W2 #g #H elim (lexs_inv_next2 … H) -H /2 width=3 by ex2_intro/ qed-.
+
+(* Basic_2A1: includes: lreq_inv_zero2 lreq_inv_succ2 *)
+lemma lreq_inv_push2: ∀J,X,K2,W2,g. X ≡[↑g] K2.ⓑ{J}W2 →
+ ∃∃K1,W1. K1 ≡[g] K2 & X = K1.ⓑ{J}W1.
+#J #X #K2 #W2 #g #H elim (lexs_inv_push2 … H) -H /2 width=4 by ex2_2_intro/ qed-.
+
+(* Basic_2A1: includes: lreq_inv_pair *)
+lemma lreq_inv_next: ∀I1,I2,L1,L2,V1,V2,f.
+ L1.ⓑ{I1}V1 ≡[⫯f] (L2.ⓑ{I2}V2) →
+ ∧∧ L1 ≡[f] L2 & V1 = V2 & I1 = I2.
+/2 width=1 by lexs_inv_next/ qed-.
+
+(* Basic_2A1: includes: lreq_inv_succ *)
+lemma lreq_inv_push: ∀I1,I2,L1,L2,V1,V2,f.
+ L1.ⓑ{I1}V1 ≡[↑f] (L2.ⓑ{I2}V2) →
+ L1 ≡[f] L2 ∧ I1 = I2.
+#I1 #I2 #L1 #L2 #V1 #V2 #f #H elim (lexs_inv_push … H) -H /2 width=1 by conj/
+qed-.
+
+(* Basic_2A1: removed theorems 5:
+ lreq_pair_lt lreq_succ_lt lreq_pair_O_Y lreq_O2 lreq_inv_O_Y
+*)