--- /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/computation/cprs_cprs.ma".
+include "basic_2/computation/lprs.ma".
+
+(* SN PARALLEL COMPUTATION ON LOCAL ENVIRONMENTS ****************************)
+
+(* Advanced properties ******************************************************)
+
+lemma lprs_pair: ∀I,G,L1,L2. ⦃G, L1⦄ ⊢ ➡* L2 →
+ ∀V1,V2. ⦃G, L1⦄ ⊢ V1 ➡* V2 → ⦃G, L1.ⓑ{I}V1⦄ ⊢ ➡* L2.ⓑ{I}V2.
+/2 width=1 by TC_lpx_sn_pair/ qed.
+
+(* Advanced inversion lemmas ************************************************)
+
+lemma lprs_inv_pair1: ∀I,G,K1,L2,V1. ⦃G, K1.ⓑ{I}V1⦄ ⊢ ➡* L2 →
+ ∃∃K2,V2. ⦃G, K1⦄ ⊢ ➡* K2 & ⦃G, K1⦄ ⊢ V1 ➡* V2 &
+ L2 = K2.ⓑ{I}V2.
+/3 width=3 by TC_lpx_sn_inv_pair1, lpr_cprs_trans/ qed-.
+
+lemma lprs_inv_pair2: ∀I,G,L1,K2,V2. ⦃G, L1⦄ ⊢ ➡* K2.ⓑ{I}V2 →
+ ∃∃K1,V1. ⦃G, K1⦄ ⊢ ➡* K2 & ⦃G, K1⦄ ⊢ V1 ➡* V2 &
+ L1 = K1.ⓑ{I}V1.
+/3 width=3 by TC_lpx_sn_inv_pair2, lpr_cprs_trans/ qed-.
+
+(* Advanced eliminators *****************************************************)
+
+lemma lprs_ind_alt: ∀G. ∀R:relation lenv.
+ R (⋆) (⋆) → (
+ ∀I,K1,K2,V1,V2.
+ ⦃G, K1⦄ ⊢ ➡* K2 → ⦃G, K1⦄ ⊢ V1 ➡* V2 →
+ R K1 K2 → R (K1.ⓑ{I}V1) (K2.ⓑ{I}V2)
+ ) →
+ ∀L1,L2. ⦃G, L1⦄ ⊢ ➡* L2 → R L1 L2.
+/3 width=4 by TC_lpx_sn_ind, lpr_cprs_trans/ qed-.
+
+(* Properties on context-sensitive parallel computation for terms ***********)
+
+lemma lprs_cpr_trans: ∀G. c_r_transitive … (cpr G) (λ_. lprs G).
+/3 width=5 by c_r_trans_LTC2, lpr_cprs_trans/ qed-.
+
+(* Basic_1: was just: pr3_pr3_pr3_t *)
+(* Note: alternative proof /3 width=5 by s_r_trans_LTC1, lprs_cpr_trans/ *)
+lemma lprs_cprs_trans: ∀G. c_rs_transitive … (cpr G) (λ_. lprs G).
+#G @c_r_to_c_rs_trans @c_r_trans_LTC2
+@c_rs_trans_TC1 /2 width=3 by lpr_cprs_trans/ (**) (* full auto too slow *)
+qed-.
+
+lemma lprs_cprs_conf_dx: ∀G,L0,T0,T1. ⦃G, L0⦄ ⊢ T0 ➡* T1 →
+ ∀L1. ⦃G, L0⦄ ⊢ ➡* L1 →
+ ∃∃T. ⦃G, L1⦄ ⊢ T1 ➡* T & ⦃G, L1⦄ ⊢ T0 ➡* T.
+#G #L0 #T0 #T1 #HT01 #L1 #H @(lprs_ind … H) -L1 /2 width=3 by ex2_intro/
+#L #L1 #_ #HL1 * #T #HT1 #HT0 -L0
+elim (cprs_lpr_conf_dx … HT1 … HL1) -HT1 #T2 #HT2
+elim (cprs_lpr_conf_dx … HT0 … HL1) -L #T3 #HT3
+elim (cprs_conf … HT2 … HT3) -T
+/3 width=5 by cprs_trans, ex2_intro/
+qed-.
+
+lemma lprs_cpr_conf_dx: ∀G,L0,T0,T1. ⦃G, L0⦄ ⊢ T0 ➡ T1 →
+ ∀L1. ⦃G, L0⦄ ⊢ ➡* L1 →
+ ∃∃T. ⦃G, L1⦄ ⊢ T1 ➡* T & ⦃G, L1⦄ ⊢ T0 ➡* T.
+/3 width=3 by lprs_cprs_conf_dx, cpr_cprs/ qed-.
+
+(* Note: this can be proved on its own using lprs_ind_dx *)
+lemma lprs_cprs_conf_sn: ∀G,L0,T0,T1. ⦃G, L0⦄ ⊢ T0 ➡* T1 →
+ ∀L1. ⦃G, L0⦄ ⊢ ➡* L1 →
+ ∃∃T. ⦃G, L0⦄ ⊢ T1 ➡* T & ⦃G, L1⦄ ⊢ T0 ➡* T.
+#G #L0 #T0 #T1 #HT01 #L1 #HL01
+elim (lprs_cprs_conf_dx … HT01 … HL01) -HT01
+/3 width=3 by lprs_cprs_trans, ex2_intro/
+qed-.
+
+lemma lprs_cpr_conf_sn: ∀G,L0,T0,T1. ⦃G, L0⦄ ⊢ T0 ➡ T1 →
+ ∀L1. ⦃G, L0⦄ ⊢ ➡* L1 →
+ ∃∃T. ⦃G, L0⦄ ⊢ T1 ➡* T & ⦃G, L1⦄ ⊢ T0 ➡* T.
+/3 width=3 by lprs_cprs_conf_sn, cpr_cprs/ qed-.
+
+lemma cprs_bind2: ∀G,L,V1,V2. ⦃G, L⦄ ⊢ V1 ➡* V2 →
+ ∀I,T1,T2. ⦃G, L.ⓑ{I}V2⦄ ⊢ T1 ➡* T2 →
+ ∀a. ⦃G, L⦄ ⊢ ⓑ{a,I}V1.T1 ➡* ⓑ{a,I}V2.T2.
+/4 width=5 by lprs_cprs_trans, lprs_pair, cprs_bind/ qed.
+
+(* Inversion lemmas on context-sensitive parallel computation for terms *****)
+
+(* Basic_1: was: pr3_gen_abst *)
+lemma cprs_inv_abst1: ∀a,G,L,W1,T1,U2. ⦃G, L⦄ ⊢ ⓛ{a}W1.T1 ➡* U2 →
+ ∃∃W2,T2. ⦃G, L⦄ ⊢ W1 ➡* W2 & ⦃G, L.ⓛW1⦄ ⊢ T1 ➡* T2 &
+ U2 = ⓛ{a}W2.T2.
+#a #G #L #V1 #T1 #U2 #H @(cprs_ind … H) -U2 /2 width=5 by ex3_2_intro/
+#U0 #U2 #_ #HU02 * #V0 #T0 #HV10 #HT10 #H destruct
+elim (cpr_inv_abst1 … HU02) -HU02 #V2 #T2 #HV02 #HT02 #H destruct
+lapply (lprs_cpr_trans … HT02 (L.ⓛV1) ?)
+/3 width=5 by lprs_pair, cprs_trans, cprs_strap1, ex3_2_intro/
+qed-.
+
+lemma cprs_inv_abst: ∀a,G,L,W1,W2,T1,T2. ⦃G, L⦄ ⊢ ⓛ{a}W1.T1 ➡* ⓛ{a}W2.T2 →
+ ⦃G, L⦄ ⊢ W1 ➡* W2 ∧ ⦃G, L.ⓛW1⦄ ⊢ T1 ➡* T2.
+#a #G #L #W1 #W2 #T1 #T2 #H elim (cprs_inv_abst1 … H) -H
+#W #T #HW1 #HT1 #H destruct /2 width=1 by conj/
+qed-.
+
+(* Basic_1: was pr3_gen_abbr *)
+lemma cprs_inv_abbr1: ∀a,G,L,V1,T1,U2. ⦃G, L⦄ ⊢ ⓓ{a}V1.T1 ➡* U2 → (
+ ∃∃V2,T2. ⦃G, L⦄ ⊢ V1 ➡* V2 & ⦃G, L.ⓓV1⦄ ⊢ T1 ➡* T2 &
+ U2 = ⓓ{a}V2.T2
+ ) ∨
+ ∃∃T2. ⦃G, L.ⓓV1⦄ ⊢ T1 ➡* T2 & ⬆[0, 1] U2 ≡ T2 & a = true.
+#a #G #L #V1 #T1 #U2 #H @(cprs_ind … H) -U2 /3 width=5 by ex3_2_intro, or_introl/
+#U0 #U2 #_ #HU02 * *
+[ #V0 #T0 #HV10 #HT10 #H destruct
+ elim (cpr_inv_abbr1 … HU02) -HU02 *
+ [ #V2 #T2 #HV02 #HT02 #H destruct
+ lapply (lprs_cpr_trans … HT02 (L.ⓓV1) ?)
+ /4 width=5 by lprs_pair, cprs_trans, cprs_strap1, ex3_2_intro, or_introl/
+ | #T2 #HT02 #HUT2
+ lapply (lprs_cpr_trans … HT02 (L.ⓓV1) ?) -HT02
+ /4 width=3 by lprs_pair, cprs_trans, ex3_intro, or_intror/
+ ]
+| #U1 #HTU1 #HU01 elim (lift_total U2 0 1)
+ #U #HU2 lapply (cpr_lift … HU02 (L.ⓓV1) … HU01 … HU2) -U0
+ /4 width=3 by cprs_strap1, drop_drop, ex3_intro, or_intror/
+]
+qed-.
+
+(* More advanced properties *************************************************)
+
+lemma lprs_pair2: ∀I,G,L1,L2. ⦃G, L1⦄ ⊢ ➡* L2 →
+ ∀V1,V2. ⦃G, L2⦄ ⊢ V1 ➡* V2 → ⦃G, L1.ⓑ{I}V1⦄ ⊢ ➡* L2.ⓑ{I}V2.
+/3 width=3 by lprs_pair, lprs_cprs_trans/ qed.
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