+++ /dev/null
-(*
- ||M|| This file is part of HELM, an Hypertextual, Electronic
- ||A|| Library of Mathematics, developed at the Computer Science
- ||T|| Department of the University of Bologna, Italy.
- ||I||
- ||T||
- ||A|| This file is distributed under the terms of the
- \ / GNU General Public License Version 2
- \ /
- V_______________________________________________________________ *)
-
-include "lambda-delta/substitution/leq_defs.ma".
-include "lambda-delta/substitution/lift_defs.ma".
-
-(* DROPPING *****************************************************************)
-
-inductive drop: lenv → nat → nat → lenv → Prop ≝
-| drop_refl: ∀L. drop L 0 0 L
-| drop_drop: ∀L1,L2,I,V,e. drop L1 0 e L2 → drop (L1. 𝕓{I} V) 0 (e + 1) L2
-| drop_skip: ∀L1,L2,I,V1,V2,d,e.
- drop L1 d e L2 → ↑[d,e] V2 ≡ V1 →
- drop (L1. 𝕓{I} V1) (d + 1) e (L2. 𝕓{I} V2)
-.
-
-interpretation "dropping" 'RDrop L1 d e L2 = (drop L1 d e L2).
-
-(* Basic inversion lemmas ***************************************************)
-
-lemma drop_inv_refl_aux: ∀d,e,L1,L2. ↓[d, e] L1 ≡ L2 → d = 0 → e = 0 → L1 = L2.
-#d #e #L1 #L2 * -d e L1 L2
-[ //
-| #L1 #L2 #I #V #e #_ #_ #H
- elim (plus_S_eq_O_false … H)
-| #L1 #L2 #I #V1 #V2 #d #e #_ #_ #H
- elim (plus_S_eq_O_false … H)
-]
-qed.
-
-lemma drop_inv_refl: ∀L1,L2. ↓[0, 0] L1 ≡ L2 → L1 = L2.
-/2 width=5/ qed.
-
-lemma drop_inv_sort1_aux: ∀d,e,L1,L2. ↓[d, e] L1 ≡ L2 → L1 = ⋆ →
- ∧∧ L2 = ⋆ & d = 0 & e = 0.
-#d #e #L1 #L2 * -d e L1 L2
-[ /2/
-| #L1 #L2 #I #V #e #_ #H destruct
-| #L1 #L2 #I #V1 #V2 #d #e #_ #_ #H destruct
-]
-qed.
-
-lemma drop_inv_sort1: ∀d,e,L2. ↓[d, e] ⋆ ≡ L2 →
- ∧∧ L2 = ⋆ & d = 0 & e = 0.
-/2/ qed.
-
-lemma drop_inv_O1_aux: ∀d,e,L1,L2. ↓[d, e] L1 ≡ L2 → d = 0 →
- ∀K,I,V. L1 = K. 𝕓{I} V →
- (e = 0 ∧ L2 = K. 𝕓{I} V) ∨
- (0 < e ∧ ↓[d, e - 1] K ≡ L2).
-#d #e #L1 #L2 * -d e L1 L2
-[ /3/
-| #L1 #L2 #I #V #e #HL12 #_ #K #J #W #H destruct -L1 I V /3/
-| #L1 #L2 #I #V1 #V2 #d #e #_ #_ #H elim (plus_S_eq_O_false … H)
-]
-qed.
-
-lemma drop_inv_O1: ∀e,K,I,V,L2. ↓[0, e] K. 𝕓{I} V ≡ L2 →
- (e = 0 ∧ L2 = K. 𝕓{I} V) ∨
- (0 < e ∧ ↓[0, e - 1] K ≡ L2).
-/2/ qed.
-
-lemma drop_inv_drop1: ∀e,K,I,V,L2.
- ↓[0, e] K. 𝕓{I} V ≡ L2 → 0 < e → ↓[0, e - 1] K ≡ L2.
-#e #K #I #V #L2 #H #He
-elim (drop_inv_O1 … H) -H * // #H destruct -e;
-elim (lt_refl_false … He)
-qed.
-
-lemma drop_inv_skip2_aux: ∀d,e,L1,L2. ↓[d, e] L1 ≡ L2 → 0 < d →
- ∀I,K2,V2. L2 = K2. 𝕓{I} V2 →
- ∃∃K1,V1. ↓[d - 1, e] K1 ≡ K2 &
- ↑[d - 1, e] V2 ≡ V1 &
- L1 = K1. 𝕓{I} V1.
-#d #e #L1 #L2 * -d e L1 L2
-[ #L #H elim (lt_refl_false … H)
-| #L1 #L2 #I #V #e #_ #H elim (lt_refl_false … H)
-| #L1 #X #Y #V1 #Z #d #e #HL12 #HV12 #_ #I #L2 #V2 #H destruct -X Y Z;
- /2 width=5/
-]
-qed.
-
-lemma drop_inv_skip2: ∀d,e,I,L1,K2,V2. ↓[d, e] L1 ≡ K2. 𝕓{I} V2 → 0 < d →
- ∃∃K1,V1. ↓[d - 1, e] K1 ≡ K2 & ↑[d - 1, e] V2 ≡ V1 &
- L1 = K1. 𝕓{I} V1.
-/2/ qed.
-
-(* Basic properties *********************************************************)
-
-lemma drop_drop_lt: ∀L1,L2,I,V,e.
- ↓[0, e - 1] L1 ≡ L2 → 0 < e → ↓[0, e] L1. 𝕓{I} V ≡ L2.
-#L1 #L2 #I #V #e #HL12 #He >(plus_minus_m_m e 1) /2/
-qed.
-
-lemma drop_fwd_drop2: ∀L1,I2,K2,V2,e. ↓[O, e] L1 ≡ K2. 𝕓{I2} V2 →
- ↓[O, e + 1] L1 ≡ K2.
-#L1 elim L1 -L1
-[ #I2 #K2 #V2 #e #H elim (drop_inv_sort1 … H) -H #H destruct
-| #K1 #I1 #V1 #IHL1 #I2 #K2 #V2 #e #H
- elim (drop_inv_O1 … H) -H * #He #H
- [ -IHL1; destruct -e K2 I2 V2 /2/
- | @drop_drop >(plus_minus_m_m e 1) /2/
- ]
-]
-qed.
-
-lemma drop_leq_drop1: ∀L1,L2,d,e. L1 [d, e] ≈ L2 →
- ∀I,K1,V,i. ↓[0, i] L1 ≡ K1. 𝕓{I} V →
- d ≤ i → i < d + e →
- ∃∃K2. K1 [0, d + e - i - 1] ≈ K2 &
- ↓[0, i] L2 ≡ K2. 𝕓{I} V.
-#L1 #L2 #d #e #H elim H -H L1 L2 d e
-[ #d #e #I #K1 #V #i #H
- elim (drop_inv_sort1 … H) -H #H destruct
-| #L1 #L2 #I1 #I2 #V1 #V2 #_ #_ #I #K1 #V #i #_ #_ #H
- elim (lt_zero_false … H)
-| #L1 #L2 #I #V #e #HL12 #IHL12 #J #K1 #W #i #H #_ #Hie
- elim (drop_inv_O1 … H) -H * #Hi #HLK1
- [ -IHL12 Hie; destruct -i K1 J W;
- <minus_n_O <minus_plus_m_m /2/
- | -HL12;
- elim (IHL12 … HLK1 ? ?) -IHL12 HLK1 // [2: /2/ ] -Hie >arith_g1 // /3/
- ]
-| #L1 #L2 #I1 #I2 #V1 #V2 #d #e #_ #IHL12 #I #K1 #V #i #H #Hdi >plus_plus_comm_23 #Hide
- lapply (plus_S_le_to_pos … Hdi) #Hi
- lapply (drop_inv_drop1 … H ?) -H // #HLK1
- elim (IHL12 … HLK1 ? ?) -IHL12 HLK1 [2: /2/ |3: /2/ ] -Hdi Hide >arith_g1 // /3/
-]
-qed.