+(**************************************************************************)
+(* ___ *)
+(* ||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/substitution/fsup.ma".
+include "basic_2/unfold/tpss_lift.ma".
+include "basic_2/unfold/ltpss_sn.ma".
+
+(* SN PARALLEL UNFOLD ON LOCAL ENVIRONMENTS *********************************)
+
+(* Properies on local environment slicing ***********************************)
+
+lemma ltpss_sn_ldrop_conf_ge: ∀L0,L1,d1,e1. L0 ⊢ ▶* [d1, e1] L1 →
+ ∀L2,e2. ⇩[0, e2] L0 ≡ L2 →
+ d1 + e1 ≤ e2 → ⇩[0, e2] L1 ≡ L2.
+#L0 #L1 #d1 #e1 #H elim H -L0 -L1 -d1 -e1
+[ #d1 #e1 #L2 #e2 #H >(ldrop_inv_atom1 … H) -H //
+| //
+| normalize #K0 #K1 #I #V0 #V1 #e1 #_ #_ #IHK01 #L2 #e2 #H #He12
+ elim (le_inv_plus_l … He12) #_ #He2
+ lapply (ldrop_inv_ldrop1 … H ?) -H // #HK0L2
+ lapply (IHK01 … HK0L2 ?) -K0 /2 width=1/
+| #K0 #K1 #I #V0 #V1 #d1 #e1 >plus_plus_comm_23 #_ #_ #IHK01 #L2 #e2 #H #Hd1e2
+ elim (le_inv_plus_l … Hd1e2) #_ #He2
+ lapply (ldrop_inv_ldrop1 … H ?) -H // #HK0L2
+ lapply (IHK01 … HK0L2 ?) -K0 /2 width=1/
+]
+qed.
+
+lemma ltpss_sn_ldrop_trans_ge: ∀L1,L0,d1,e1. L1 ⊢ ▶* [d1, e1] L0 →
+ ∀L2,e2. ⇩[0, e2] L0 ≡ L2 →
+ d1 + e1 ≤ e2 → ⇩[0, e2] L1 ≡ L2.
+#L1 #L0 #d1 #e1 #H elim H -L1 -L0 -d1 -e1
+[ #d1 #e1 #L2 #e2 #H >(ldrop_inv_atom1 … H) -H //
+| //
+| normalize #K1 #K0 #I #V1 #V0 #e1 #_ #_ #IHK10 #L2 #e2 #H #He12
+ elim (le_inv_plus_l … He12) #_ #He2
+ lapply (ldrop_inv_ldrop1 … H ?) -H // #HK0L2
+ lapply (IHK10 … HK0L2 ?) -K0 /2 width=1/
+| #K0 #K1 #I #V1 #V0 #d1 #e1 >plus_plus_comm_23 #_ #_ #IHK10 #L2 #e2 #H #Hd1e2
+ elim (le_inv_plus_l … Hd1e2) #_ #He2
+ lapply (ldrop_inv_ldrop1 … H ?) -H // #HK0L2
+ lapply (IHK10 … HK0L2 ?) -IHK10 -HK0L2 /2 width=1/
+]
+qed.
+
+lemma ltpss_sn_ldrop_conf_be: ∀L0,L1,d1,e1. L0 ⊢ ▶* [d1, e1] L1 →
+ ∀L2,e2. ⇩[0, e2] L0 ≡ L2 → d1 ≤ e2 → e2 ≤ d1 + e1 →
+ ∃∃L. L2 ⊢ ▶* [0, d1 + e1 - e2] L & ⇩[0, e2] L1 ≡ L.
+#L0 #L1 #d1 #e1 #H elim H -L0 -L1 -d1 -e1
+[ #d1 #e1 #L2 #e2 #H >(ldrop_inv_atom1 … H) -H /2 width=3/
+| normalize #L #I #V #L2 #e2 #HL2 #_ #He2
+ lapply (le_n_O_to_eq … He2) -He2 #H destruct
+ lapply (ldrop_inv_refl … HL2) -HL2 #H destruct /2 width=3/
+| normalize #K0 #K1 #I #V0 #V1 #e1 #HK01 #HV01 #IHK01 #L2 #e2 #H #_ #He21
+ lapply (ldrop_inv_O1 … H) -H * * #He2 #HK0L2
+ [ -IHK01 -He21 destruct <minus_n_O /3 width=3/
+ | -HK01 -HV01 <minus_le_minus_minus_comm //
+ elim (IHK01 … HK0L2 ? ?) -K0 // /2 width=1/ /3 width=3/
+ ]
+| #K0 #K1 #I #V0 #V1 #d1 #e1 >plus_plus_comm_23 #_ #_ #IHK01 #L2 #e2 #H #Hd1e2 #He2de1
+ elim (le_inv_plus_l … Hd1e2) #_ #He2
+ <minus_le_minus_minus_comm //
+ lapply (ldrop_inv_ldrop1 … H ?) -H // #HK0L2
+ elim (IHK01 … HK0L2 ? ?) -K0 /2 width=1/ /3 width=3/
+]
+qed.
+
+lemma ltpss_sn_ldrop_trans_be: ∀L1,L0,d1,e1. L1 ⊢ ▶* [d1, e1] L0 →
+ ∀L2,e2. ⇩[0, e2] L0 ≡ L2 → d1 ≤ e2 → e2 ≤ d1 + e1 →
+ ∃∃L. L ⊢ ▶* [0, d1 + e1 - e2] L2 & ⇩[0, e2] L1 ≡ L.
+#L1 #L0 #d1 #e1 #H elim H -L1 -L0 -d1 -e1
+[ #d1 #e1 #L2 #e2 #H >(ldrop_inv_atom1 … H) -H /2 width=3/
+| normalize #L #I #V #L2 #e2 #HL2 #_ #He2
+ lapply (le_n_O_to_eq … He2) -He2 #H destruct
+ lapply (ldrop_inv_refl … HL2) -HL2 #H destruct /2 width=3/
+| normalize #K1 #K0 #I #V1 #V0 #e1 #HK10 #HV10 #IHK10 #L2 #e2 #H #_ #He21
+ lapply (ldrop_inv_O1 … H) -H * * #He2 #HK0L2
+ [ -IHK10 -He21 destruct <minus_n_O /3 width=3/
+ | -HK10 -HV10 <minus_le_minus_minus_comm //
+ elim (IHK10 … HK0L2 ? ?) -K0 // /2 width=1/ /3 width=3/
+ ]
+| #K1 #K0 #I #V1 #V0 #d1 #e1 >plus_plus_comm_23 #_ #_ #IHK10 #L2 #e2 #H #Hd1e2 #He2de1
+ elim (le_inv_plus_l … Hd1e2) #_ #He2
+ <minus_le_minus_minus_comm //
+ lapply (ldrop_inv_ldrop1 … H ?) -H // #HK0L2
+ elim (IHK10 … HK0L2 ? ?) -K0 /2 width=1/ /3 width=3/
+]
+qed.
+
+lemma ltpss_sn_ldrop_conf_le: ∀L0,L1,d1,e1. L0 ⊢ ▶* [d1, e1] L1 →
+ ∀L2,e2. ⇩[0, e2] L0 ≡ L2 → e2 ≤ d1 →
+ ∃∃L. L2 ⊢ ▶* [d1 - e2, e1] L & ⇩[0, e2] L1 ≡ L.
+#L0 #L1 #d1 #e1 #H elim H -L0 -L1 -d1 -e1
+[ #d1 #e1 #L2 #e2 #H >(ldrop_inv_atom1 … H) -H /2 width=3/
+| /2 width=3/
+| normalize #K0 #K1 #I #V0 #V1 #e1 #HK01 #HV01 #_ #L2 #e2 #H #He2
+ lapply (le_n_O_to_eq … He2) -He2 #He2 destruct
+ lapply (ldrop_inv_refl … H) -H #H destruct /3 width=3/
+| #K0 #K1 #I #V0 #V1 #d1 #e1 #HK01 #HV01 #IHK01 #L2 #e2 #H #He2d1
+ lapply (ldrop_inv_O1 … H) -H * * #He2 #HK0L2
+ [ -IHK01 -He2d1 destruct <minus_n_O /3 width=3/
+ | -HK01 -HV01 <minus_le_minus_minus_comm //
+ elim (IHK01 … HK0L2 ?) -K0 /2 width=1/ /3 width=3/
+ ]
+]
+qed.
+
+lemma ltpss_sn_ldrop_trans_le: ∀L1,L0,d1,e1. L1 ⊢ ▶* [d1, e1] L0 →
+ ∀L2,e2. ⇩[0, e2] L0 ≡ L2 → e2 ≤ d1 →
+ ∃∃L. L ⊢ ▶* [d1 - e2, e1] L2 & ⇩[0, e2] L1 ≡ L.
+#L1 #L0 #d1 #e1 #H elim H -L1 -L0 -d1 -e1
+[ #d1 #e1 #L2 #e2 #H >(ldrop_inv_atom1 … H) -H /2 width=3/
+| /2 width=3/
+| normalize #K1 #K0 #I #V1 #V0 #e1 #HK10 #HV10 #_ #L2 #e2 #H #He2
+ lapply (le_n_O_to_eq … He2) -He2 #He2 destruct
+ lapply (ldrop_inv_refl … H) -H #H destruct /3 width=3/
+| #K1 #K0 #I #V1 #V0 #d1 #e1 #HK10 #HV10 #IHK10 #L2 #e2 #H #He2d1
+ lapply (ldrop_inv_O1 … H) -H * * #He2 #HK0L2
+ [ -IHK10 -He2d1 destruct <minus_n_O /3 width=3/
+ | -HK10 -HV10 <minus_le_minus_minus_comm //
+ elim (IHK10 … HK0L2 ?) -K0 /2 width=1/ /3 width=3/
+ ]
+]
+qed.
+
+lemma ldrop_ltpss_sn_trans_le: ∀L1,K1,d1,e1. ⇩[d1, e1] L1 ≡ K1 →
+ ∀K2,d2,e2. K1 ⊢ ▶* [d2, e2] K2 → d1 ≤ d2 →
+ ∃∃L2. L1 ⊢ ▶* [d2 + e1, e2] L2 & ⇩[d1, e1] L2 ≡ K2.
+#L1 #K1 #d1 #e1 #H elim H -L1 -K1 -d1 -e1
+[ #d1 #e1 #K2 #d2 #e2 #H #_
+ >(ltpss_sn_inv_atom1 … H) -H /2 width=3/
+| /2 width=3/
+| #L1 #K1 #I #V #e1 #_ #IHLK1 #K2 #d2 #e2 #HK12 #Hd
+ elim (IHLK1 … HK12 Hd) -K1 -Hd /3 width=5/
+| #L1 #K1 #I #V1 #W1 #d1 #e1 #HLK1 #HWV1 #IHLK1 #X #d2 #e2 #H #Hd12
+ elim (le_inv_plus_l … Hd12) -Hd12 #Hd12 #Hd2
+ elim (ltpss_sn_inv_tpss11 … H Hd2) -H #K2 #W2 #HK12 #HW12 #H destruct
+ elim (IHLK1 … HK12 … Hd12) -IHLK1 -HK12 <le_plus_minus_comm // #L2 #HL12 #HLK2
+ elim (lift_total W2 d1 e1) #V2 #HWV2
+ lapply (tpss_lift_ge … HW12 … HLK1 HWV1 … HWV2) -HLK1 -W1 // -Hd12
+ <le_plus_minus_comm // /4 width=5/
+]
+qed-.
+
+lemma ldrop_ltpss_sn_trans_be: ∀L1,K1,d1,e1. ⇩[d1, e1] L1 ≡ K1 →
+ ∀K2,d2,e2. K1 ⊢ ▶* [d2, e2] K2 →
+ d2 ≤ d1 → d1 ≤ d2 + e2 →
+ ∃∃L2. L1 ⊢ ▶* [d2, e1 + e2] L2 &
+ ⇩[d1, e1] L2 ≡ K2.
+#L1 #K1 #d1 #e1 #H elim H -L1 -K1 -d1 -e1
+[ #d1 #e1 #K2 #d2 #e2 #H #_ #_
+ >(ltpss_sn_inv_atom1 … H) -H /2 width=3/
+| #K1 #I #V1 #K2 #d2 #e2 #HK12 #H #_
+ lapply (le_n_O_to_eq … H) -H #H destruct /2 width=3/
+| #L1 #K1 #I #V #e1 #_ #IHLK1 #K2 #d2 #e2 #HK12 #H1 #H2
+ elim (IHLK1 … HK12 H1 H2) -K1 -H2
+ lapply (le_n_O_to_eq … H1) -H1 #H destruct /3 width=5/
+| #L1 #K1 #I #V1 #W1 #d1 #e1 #HLK1 #HWV1 #IHLK1 #X #d2 #e2 #H #Hd21 #Hd12
+ elim (eq_or_gt d2) #Hd2 [ -Hd21 elim (eq_or_gt e2) #He2 ] destruct
+ [ lapply (le_n_O_to_eq … Hd12) -Hd12 <plus_n_Sm #H destruct
+ | elim (ltpss_sn_inv_tpss21 … H He2) -H #K2 #W2 #HK12 #HW12 #H destruct
+ elim (IHLK1 … HK12 …) -IHLK1 // /2 width=1/ >plus_minus_commutative // #L2 #HL12 #HLK2
+ elim (lift_total W2 d1 e1) #V2 #HWV2
+ lapply (tpss_lift_be … HW12 … HLK1 HWV1 … HWV2) -HLK1 -W1 // /2 width=1/
+ >plus_minus // >commutative_plus /4 width=5/
+ | elim (ltpss_sn_inv_tpss11 … H Hd2) -H #K2 #W2 #HK12 #HW12 #H destruct
+ elim (IHLK1 … HK12 …) -IHLK1 [2: >plus_minus // ] /2 width=1/ #L2 #HL12 #HLK2
+ elim (lift_total W2 d1 e1) #V2 #HWV2
+ lapply (tpss_lift_be … HW12 … HLK1 HWV1 … HWV2) -HLK1 -W1 [ >plus_minus // ] /2 width=1/
+ >commutative_plus /3 width=5/
+ ]
+]
+qed-.
+
+lemma ldrop_ltpss_sn_trans_ge: ∀L1,K1,d1,e1. ⇩[d1, e1] L1 ≡ K1 →
+ ∀K2,d2,e2. K1 ⊢ ▶* [d2, e2] K2 → d2 + e2 ≤ d1 →
+ ∃∃L2. L1 ⊢ ▶* [d2, e2] L2 & ⇩[d1, e1] L2 ≡ K2.
+#L1 #K1 #d1 #e1 #H elim H -L1 -K1 -d1 -e1
+[ #d1 #e1 #K2 #d2 #e2 #H #_
+ >(ltpss_sn_inv_atom1 … H) -H /2 width=3/
+| #K1 #I #V1 #K2 #d2 #e2 #HK12 #H
+ elim (plus_le_0 … H) -H #H1 #H2 destruct /2 width=3/
+| #L1 #K1 #I #V #e1 #_ #IHLK1 #K2 #d2 #e2 #HK12 #H
+ elim (IHLK1 … HK12 H) -K1
+ elim (plus_le_0 … H) -H #H1 #H2 destruct #L2 #HL12
+ >(ltpss_sn_inv_refl_O2 … HL12) -L1 /3 width=5/
+| #L1 #K1 #I #V1 #W1 #d1 #e1 #HLK1 #HWV1 #IHLK1 #X #d2 #e2 #H #Hd21
+ elim (eq_or_gt d2) #Hd2 [ elim (eq_or_gt e2) #He2 ] destruct
+ [ -IHLK1 -Hd21 <(ltpss_sn_inv_refl_O2 … H) -X /3 width=5/
+ | elim (ltpss_sn_inv_tpss21 … H He2) -H #K2 #W2 #HK12 #HW12 #H destruct
+ elim (IHLK1 … HK12 …) -IHLK1 /2 width=1/ #L2 #HL12 #HLK2
+ elim (lift_total W2 d1 e1) #V2 #HWV2
+ lapply (tpss_lift_le … HW12 … HLK1 HWV1 … HWV2) -HLK1 -W1 /2 width=1/ /3 width=5/
+ | elim (ltpss_sn_inv_tpss11 … H Hd2) -H #K2 #W2 #HK12 #HW12 #H destruct
+ elim (IHLK1 … HK12 …) -IHLK1 [2: >plus_minus // /2 width=1/ ] #L2 #HL12 #HLK2
+ elim (lift_total W2 d1 e1) #V2 #HWV2
+ lapply (tpss_lift_le … HW12 … HLK1 HWV1 … HWV2) -HLK1 -W1 [ >plus_minus // /2 width=1/ ] /3 width=5/
+ ]
+]
+qed-.
+
+(* Properties on supclosure *************************************************)
+
+lemma fsup_tpss_trans_full: ∀L1,L2,T1,T2. ⦃L1, T1⦄ ⊃ ⦃L2, T2⦄ → ∀U2. L2 ⊢ T2 ▶*[0,|L2|] U2 →
+ ∃∃L,U1. L1 ⊢ ▶*[0,|L1|] L & L ⊢ T1 ▶*[0,|L|] U1 & ⦃L, U1⦄ ⊃ ⦃L2, T2⦄.
+#L1 #L2 #T1 #T2 #H elim H -L1 -L2 -T1 -T2 [1,2,3,4,5: /3 width=5/ ]
+#L1 #K1 #K2 #T1 #T2 #U1 #d #e #HLK1 #HTU1 #_ #IHT12 #U2 #HTU2
+elim (IHT12 … HTU2) -IHT12 -HTU2 #K #T #HK1 #HT1 #HT2
+elim (lift_total T d e) #U #HTU
+lapply (ltpss_sn_fwd_length … HK1) #H >H in HK1; -H #HK1
+elim (le_or_ge d (|K|)) #Hd
+[ elim (ldrop_ltpss_sn_trans_be … HLK1 … HK1 … Hd) // -HLK1 -HK1 #L2 #HL12 #HL2K
+ lapply (tpss_lift_be … HT1 … Hd HL2K HTU1 … HTU) // -HT1 -HTU1 #HU1
+| elim (ldrop_ltpss_sn_trans_ge … HLK1 … HK1 Hd) -HLK1 -HK1 #L2 #HL12 #HL2K
+ lapply (tpss_lift_le … HT1 … Hd HL2K HTU1 … HTU) -HT1 -HTU1 #HU1
+]
+lapply (ltpss_sn_weak_full … HL12) -HL12 #HL12
+lapply (tpss_weak_full … HU1) -HU1 #HU1
+@(ex3_2_intro … L2 U) // /2 width=7/ (**) (* explicit constructor: auto /3 width=14/ too slow *)
+qed-.