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4 (* ||A|| A project by Andrea Asperti *)
6 (* ||I|| Developers: *)
7 (* ||T|| The HELM team. *)
8 (* ||A|| http://helm.cs.unibo.it *)
10 (* \ / This file is distributed under the terms of the *)
11 (* v GNU General Public License Version 2 *)
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15 include "ground_2/xoa/ex_3_4.ma".
16 include "ground_2/xoa/ex_4_1.ma".
17 include "static_2/notation/relations/voidstareq_4.ma".
18 include "static_2/syntax/lenv.ma".
20 (* EQUIVALENCE FOR LOCAL ENVIRONMENTS UP TO EXCLUSION BINDERS ***************)
22 inductive lveq: bi_relation nat lenv ≝
23 | lveq_atom : lveq 0 (⋆) 0 (⋆)
24 | lveq_bind : ∀I1,I2,K1,K2. lveq 0 K1 0 K2 →
25 lveq 0 (K1.ⓘ[I1]) 0 (K2.ⓘ[I2])
26 | lveq_void_sn: ∀K1,K2,n1. lveq n1 K1 0 K2 →
27 lveq (↑n1) (K1.ⓧ) 0 K2
28 | lveq_void_dx: ∀K1,K2,n2. lveq 0 K1 n2 K2 →
29 lveq 0 K1 (↑n2) (K2.ⓧ)
32 interpretation "equivalence up to exclusion binders (local environment)"
33 'VoidStarEq L1 n1 n2 L2 = (lveq n1 L1 n2 L2).
35 (* Basic properties *********************************************************)
37 lemma lveq_refl: ∀L. L ≋ⓧ*[0,0] L.
38 #L elim L -L /2 width=1 by lveq_atom, lveq_bind/
41 lemma lveq_sym: bi_symmetric … lveq.
42 #n1 #n2 #L1 #L2 #H elim H -L1 -L2 -n1 -n2
43 /2 width=1 by lveq_atom, lveq_bind, lveq_void_sn, lveq_void_dx/
46 (* Basic inversion lemmas ***************************************************)
48 fact lveq_inv_zero_aux: ∀L1,L2,n1,n2. L1 ≋ⓧ*[n1,n2] L2 →
51 | ∃∃I1,I2,K1,K2. K1 ≋ⓧ*[0,0] K2 & K1.ⓘ[I1] = L1 & K2.ⓘ[I2] = L2.
52 #L1 #L2 #n1 #n2 * -L1 -L2 -n1 -n2
53 [1: /3 width=1 by or_introl, conj/
54 |2: /3 width=7 by ex3_4_intro, or_intror/
55 |*: #K1 #K2 #n #_ #H1 #H2 destruct
59 lemma lveq_inv_zero: ∀L1,L2. L1 ≋ⓧ*[0,0] L2 →
61 | ∃∃I1,I2,K1,K2. K1 ≋ⓧ*[0,0] K2 & K1.ⓘ[I1] = L1 & K2.ⓘ[I2] = L2.
62 /2 width=5 by lveq_inv_zero_aux/ qed-.
64 fact lveq_inv_succ_sn_aux: ∀L1,L2,n1,n2. L1 ≋ⓧ*[n1,n2] L2 →
66 ∃∃K1. K1 ≋ⓧ*[m1,0] L2 & K1.ⓧ = L1 & 0 = n2.
67 #L1 #L2 #n1 #n2 * -L1 -L2 -n1 -n2
69 |2: #I1 #I2 #K1 #K2 #_ #m #H destruct
70 |*: #K1 #K2 #n #HK #m #H destruct /2 width=3 by ex3_intro/
74 lemma lveq_inv_succ_sn: ∀L1,K2,n1,n2. L1 ≋ⓧ*[↑n1,n2] K2 →
75 ∃∃K1. K1 ≋ⓧ*[n1,0] K2 & K1.ⓧ = L1 & 0 = n2.
76 /2 width=3 by lveq_inv_succ_sn_aux/ qed-.
78 lemma lveq_inv_succ_dx: ∀K1,L2,n1,n2. K1 ≋ⓧ*[n1,↑n2] L2 →
79 ∃∃K2. K1 ≋ⓧ*[0,n2] K2 & K2.ⓧ = L2 & 0 = n1.
81 lapply (lveq_sym … H) -H #H
82 elim (lveq_inv_succ_sn … H) -H /3 width=3 by lveq_sym, ex3_intro/
85 fact lveq_inv_succ_aux: ∀L1,L2,n1,n2. L1 ≋ⓧ*[n1,n2] L2 →
86 ∀m1,m2. ↑m1 = n1 → ↑m2 = n2 → ⊥.
87 #L1 #L2 #n1 #n2 * -L1 -L2 -n1 -n2
88 [1: #m1 #m2 #H1 #H2 destruct
89 |2: #I1 #I2 #K1 #K2 #_ #m1 #m2 #H1 #H2 destruct
90 |*: #K1 #K2 #n #_ #m1 #m2 #H1 #H2 destruct
94 lemma lveq_inv_succ: ∀L1,L2,n1,n2. L1 ≋ⓧ*[↑n1,↑n2] L2 → ⊥.
95 /2 width=9 by lveq_inv_succ_aux/ qed-.
97 (* Advanced inversion lemmas ************************************************)
99 lemma lveq_inv_bind: ∀I1,I2,K1,K2. K1.ⓘ[I1] ≋ⓧ*[0,0] K2.ⓘ[I2] → K1 ≋ⓧ*[0,0] K2.
101 elim (lveq_inv_zero … H) -H * [| #Z1 #Z2 #Y1 #Y2 #HY ] #H1 #H2 destruct //
104 lemma lveq_inv_atom_atom: ∀n1,n2. ⋆ ≋ⓧ*[n1,n2] ⋆ → ∧∧ 0 = n1 & 0 = n2.
105 * [2: #n1 ] * [2,4: #n2 ] #H
106 [ elim (lveq_inv_succ … H)
107 | elim (lveq_inv_succ_dx … H) -H #Y #_ #H1 #H2 destruct
108 | elim (lveq_inv_succ_sn … H) -H #Y #_ #H1 #H2 destruct
109 | /2 width=1 by conj/
113 lemma lveq_inv_bind_atom: ∀I1,K1,n1,n2. K1.ⓘ[I1] ≋ⓧ*[n1,n2] ⋆ →
114 ∃∃m1. K1 ≋ⓧ*[m1,0] ⋆ & BUnit Void = I1 & ↑m1 = n1 & 0 = n2.
115 #I1 #K1 * [2: #n1 ] * [2,4: #n2 ] #H
116 [ elim (lveq_inv_succ … H)
117 | elim (lveq_inv_succ_dx … H) -H #Y #_ #H1 #H2 destruct
118 | elim (lveq_inv_succ_sn … H) -H #Y #HY #H1 #H2 destruct /2 width=3 by ex4_intro/
119 | elim (lveq_inv_zero … H) -H *
121 | #Z1 #Z2 #Y1 #Y2 #_ #H1 #H2 destruct
126 lemma lveq_inv_atom_bind: ∀I2,K2,n1,n2. ⋆ ≋ⓧ*[n1,n2] K2.ⓘ[I2] →
127 ∃∃m2. ⋆ ≋ⓧ*[0,m2] K2 & BUnit Void = I2 & 0 = n1 & ↑m2 = n2.
129 lapply (lveq_sym … H) -H #H
130 elim (lveq_inv_bind_atom … H) -H
131 /3 width=3 by lveq_sym, ex4_intro/
134 lemma lveq_inv_pair_pair: ∀I1,I2,K1,K2,V1,V2,n1,n2. K1.ⓑ[I1]V1 ≋ⓧ*[n1,n2] K2.ⓑ[I2]V2 →
135 ∧∧ K1 ≋ⓧ*[0,0] K2 & 0 = n1 & 0 = n2.
136 #I1 #I2 #K1 #K2 #V1 #V2 * [2: #n1 ] * [2,4: #n2 ] #H
137 [ elim (lveq_inv_succ … H)
138 | elim (lveq_inv_succ_dx … H) -H #Y #_ #H1 #H2 destruct
139 | elim (lveq_inv_succ_sn … H) -H #Y #_ #H1 #H2 destruct
140 | elim (lveq_inv_zero … H) -H *
142 | #Z1 #Z2 #Y1 #Y2 #HY #H1 #H2 destruct /3 width=1 by and3_intro/
147 lemma lveq_inv_void_succ_sn: ∀L1,L2,n1,n2. L1.ⓧ ≋ⓧ*[↑n1,n2] L2 →
148 ∧∧ L1 ≋ ⓧ*[n1,0] L2 & 0 = n2.
150 elim (lveq_inv_succ_sn … H) -H #Y #HY #H1 #H2 destruct /2 width=1 by conj/
153 lemma lveq_inv_void_succ_dx: ∀L1,L2,n1,n2. L1 ≋ⓧ*[n1,↑n2] L2.ⓧ →
154 ∧∧ L1 ≋ ⓧ*[0,n2] L2 & 0 = n1.
156 lapply (lveq_sym … H) -H #H
157 elim (lveq_inv_void_succ_sn … H) -H
158 /3 width=1 by lveq_sym, conj/
161 (* Advanced forward lemmas **************************************************)
163 lemma lveq_fwd_gen: ∀L1,L2,n1,n2. L1 ≋ⓧ*[n1,n2] L2 →
165 #L1 #L2 * [2: #n1 ] * [2,4: #n2 ] #H
166 [ elim (lveq_inv_succ … H) ]
167 /2 width=1 by or_introl, or_intror/
170 lemma lveq_fwd_pair_sn: ∀I1,K1,L2,V1,n1,n2. K1.ⓑ[I1]V1 ≋ⓧ*[n1,n2] L2 → 0 = n1.
171 #I1 #K1 #L2 #V1 * [2: #n1 ] // * [2: #n2 ] #H
172 [ elim (lveq_inv_succ … H)
173 | elim (lveq_inv_succ_sn … H) -H #Y #_ #H1 #H2 destruct
177 lemma lveq_fwd_pair_dx: ∀I2,L1,K2,V2,n1,n2. L1 ≋ⓧ*[n1,n2] K2.ⓑ[I2]V2 → 0 = n2.
178 /3 width=6 by lveq_fwd_pair_sn, lveq_sym/ qed-.