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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 *)
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11 (* v GNU General Public License Version 2 *)
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15 include "basic_2/substitution/cofrees_lift.ma".
16 include "basic_2/substitution/llpx_sn_alt1.ma".
18 lemma le_plus_xSy_O_false: ∀x,y. x + S y ≤ 0 → ⊥.
19 #x #y #H lapply (le_n_O_to_eq … H) -H <plus_n_Sm #H destruct
22 lemma ldrop_fwd_length_ge: ∀L1,L2,d,e,s. ⇩[s, d, e] L1 ≡ L2 → |L1| ≤ d → |L2| = |L1|.
23 #L1 #L2 #d #e #s #H elim H -L1 -L2 -d -e // normalize
24 [ #I #L1 #L2 #V #e #_ #_ #H elim (le_plus_xSy_O_false … H)
25 | /4 width=2 by le_plus_to_le_r, eq_f/
29 lemma ldrop_fwd_length_le_le: ∀L1,L2,d,e,s. ⇩[s, d, e] L1 ≡ L2 → d ≤ |L1| → e ≤ |L1| - d → |L2| = |L1| - e.
30 #L1 #L2 #d #e #s #H elim H -L1 -L2 -d -e // normalize
31 [ /3 width=2 by le_plus_to_le_r/
32 | #I #L1 #L2 #V1 #V2 #d #e #_ #_ #IHL12 >minus_plus_plus_l
33 #Hd #He lapply (le_plus_to_le_r … Hd) -Hd
34 #Hd >IHL12 // -L2 >plus_minus /2 width=3 by transitive_le/
38 lemma ldrop_fwd_length_le_ge: ∀L1,L2,d,e,s. ⇩[s, d, e] L1 ≡ L2 → d ≤ |L1| → |L1| - d ≤ e → |L2| = d.
39 #L1 #L2 #d #e #s #H elim H -L1 -L2 -d -e normalize
40 [ /2 width=1 by le_n_O_to_eq/
41 | #I #L #V #_ <minus_n_O #H elim (le_plus_xSy_O_false … H)
42 | /3 width=2 by le_plus_to_le_r/
43 | /4 width=2 by le_plus_to_le_r, eq_f/
47 lemma ldrop_O1_le: ∀s,e,L. e ≤ |L| → ∃K. ⇩[s, 0, e] L ≡ K.
48 #s #e @(nat_ind_plus … e) -e /2 width=2 by ex_intro/
50 [ #H elim (le_plus_xSy_O_false … H)
51 | #L #I #V normalize #H elim (IHe L) -IHe /3 width=2 by ldrop_drop, monotonic_pred, ex_intro/
55 lemma ldrop_O1_lt: ∀s,L,e. e < |L| → ∃∃I,K,V. ⇩[s, 0, e] L ≡ K.ⓑ{I}V.
57 [ #e #H elim (lt_zero_false … H)
58 | #L #I #V #IHL #e @(nat_ind_plus … e) -e /2 width=4 by ldrop_pair, ex1_3_intro/
59 #e #_ normalize #H elim (IHL e) -IHL /3 width=4 by ldrop_drop, lt_plus_to_minus_r, lt_plus_to_lt_l, ex1_3_intro/
63 lemma ldrop_O1_pair: ∀L,K,e,s. ⇩[s, 0, e] L ≡ K → e ≤ |L| → ∀I,V.
64 ∃∃J,W. ⇩[s, 0, e] L.ⓑ{I}V ≡ K.ⓑ{J}W.
65 #L elim L -L [| #L #Z #X #IHL ] #K #e #s #H normalize #He #I #V
66 [ elim (ldrop_inv_atom1 … H) -H #H <(le_n_O_to_eq … He) -e
67 #Hs destruct /2 width=3 by ex1_2_intro/
68 | elim (ldrop_inv_O1_pair1 … H) -H * #He #HLK destruct /2 width=3 by ex1_2_intro/
69 elim (IHL … HLK … Z X) -IHL -HLK
70 /3 width=3 by ldrop_drop_lt, le_plus_to_minus, ex1_2_intro/
74 lemma ldrop_inv_O1_gt: ∀L,K,e,s. ⇩[s, 0, e] L ≡ K → |L| < e →
76 #L elim L -L [| #L #Z #X #IHL ] #K #e #s #H normalize in ⊢ (?%?→?); #H1e
77 [ elim (ldrop_inv_atom1 … H) -H elim s -s /2 width=1 by conj/
78 #_ #Hs lapply (Hs ?) // -Hs #H destruct elim (lt_zero_false … H1e)
79 | elim (ldrop_inv_O1_pair1 … H) -H * #H2e #HLK destruct
80 [ elim (lt_zero_false … H1e)
81 | elim (IHL … HLK) -IHL -HLK /2 width=1 by lt_plus_to_minus_r, conj/
86 lemma ldrop_O1_ge: ∀L,e. |L| ≤ e → ⇩[Ⓣ, 0, e] L ≡ ⋆.
87 #L elim L -L [ #e #_ @ldrop_atom #H destruct ]
88 #L #I #V #IHL #e @(nat_ind_plus … e) -e [ #H elim (le_plus_xSy_O_false … H) ]
89 normalize /4 width=1 by ldrop_drop, monotonic_pred/
92 lemma ldrop_split: ∀L1,L2,d,e2,s. ⇩[s, d, e2] L1 ≡ L2 → ∀e1. e1 ≤ e2 →
93 ∃∃L. ⇩[s, d, e2 - e1] L1 ≡ L & ⇩[s, d, e1] L ≡ L2.
94 #L1 #L2 #d #e2 #s #H elim H -L1 -L2 -d -e2
95 [ #d #e2 #Hs #e1 #He12 @(ex2_intro … (⋆))
96 @ldrop_atom #H lapply (Hs H) -s #H destruct /2 width=1 by le_n_O_to_eq/
97 | #I #L1 #V #e1 #He1 lapply (le_n_O_to_eq … He1) -He1
98 #H destruct /2 width=3 by ex2_intro/
99 | #I #L1 #L2 #V #e2 #HL12 #IHL12 #e1 @(nat_ind_plus … e1) -e1
100 [ /3 width=3 by ldrop_drop, ex2_intro/
101 | -HL12 #e1 #_ #He12 lapply (le_plus_to_le_r … He12) -He12
102 #He12 elim (IHL12 … He12) -IHL12 >minus_plus_plus_l
103 #L #HL1 #HL2 elim (lt_or_ge (|L1|) (e2-e1)) #H0
104 [ elim (ldrop_inv_O1_gt … HL1 H0) -HL1 #H1 #H2 destruct
105 elim (ldrop_inv_atom1 … HL2) -HL2 #H #_ destruct
106 @(ex2_intro … (⋆)) [ @ldrop_O1_ge normalize // ]
107 @ldrop_atom #H destruct
108 | elim (ldrop_O1_pair … HL1 H0 I V) -HL1 -H0 /3 width=5 by ldrop_drop, ex2_intro/
111 | #I #L1 #L2 #V1 #V2 #d #e2 #_ #HV21 #IHL12 #e1 #He12 elim (IHL12 … He12) -IHL12
112 #L #HL1 #HL2 elim (lift_split … HV21 d e1) -HV21 /3 width=5 by ldrop_skip, ex2_intro/
116 (* LAZY SN POINTWISE EXTENSION OF A CONTEXT-SENSITIVE REALTION FOR TERMS ****)
118 (* alternative definition of llpx_sn (not recursive) *)
119 definition llpx_sn_alt2: relation4 bind2 lenv term term → relation4 ynat term lenv lenv ≝
120 λR,d,T,L1,L2. |L1| = |L2| ∧
121 (∀I1,I2,K1,K2,V1,V2,i. d ≤ yinj i → (L1 ⊢ i ~ϵ 𝐅*[d]⦃T⦄ → ⊥) →
122 ⇩[i] L1 ≡ K1.ⓑ{I1}V1 → ⇩[i] L2 ≡ K2.ⓑ{I2}V2 →
123 I1 = I2 ∧ R I1 K1 V1 V2
126 (* Main properties **********************************************************)
128 lemma cpy_inv_nlift2_be: ∀G,L,U1,U2,d. ⦃G, L⦄ ⊢ U1 ▶[d, ∞] U2 → ∀i. d ≤ yinj i →
129 ∀K,s. ⇩[s, i, 1] L ≡ K →
130 (∀T2. ⇧[i, 1] T2 ≡ U2 → ⊥) → (∀T1. ⇧[i, 1] T1 ≡ U1 → ⊥).
131 #G #L #U1 #U2 #d #HU12 #i #Hdi #K #s #HLK #HnU2 #T1 #HTU1
132 elim (cpy_inv_lift1_be … HU12 … HLK … HTU1) /2 width=2 by/
135 lemma cpy_inv_nlift2_ge: ∀G,L,U1,U2,d,e. ⦃G, L⦄ ⊢ U1 ▶[d, e] U2 →
136 ∀i. d ≤ yinj i → (* yinj i + yinj 1 ≤ d + e → *)
137 (∀T2. ⇧[i, 1] T2 ≡ U2 → ⊥) →
138 ∃∃j. d ≤ yinj j & j ≤ i & (∀T1. ⇧[j, 1] T1 ≡ U1 → ⊥).
139 #G #L #U1 #U2 #d #e #H elim H -G -L -U1 -U2 -d -e
140 [ #I #G #L #d #e #i #Hdi (* #Hide *) #H @(ex3_intro … i) /2 width=2 by/
141 | #I #G #L #K #V #W #j #d #e #Hdj #Hjde #HLK #HVW #i #Hdi (* #Hide *) #HnW
142 elim (le_or_ge i j) #Hij [2: @(ex3_intro … j) /2 width=7 by lift_inv_lref2_be/ ]
143 elim (lift_split … HVW i j) -HVW //
144 #X #_ #H elim HnW -HnW //
145 | #a #I #G #L #W1 #W2 #U1 #U2 #d #e #_ #_ #IHW12 #IHU12 #i #Hdi #H elim (nlift_inv_bind … H) -H
146 [ #HnW2 elim (IHW12 … HnW2) -IHW12 -HnW2 -IHU12 //
147 #j #Hdj #Hji #HnW1 @(ex3_intro … j) /3 width=9 by nlift_bind_sn/
148 | #HnU2 elim (IHU12 … HnU2) -IHU12 -HnU2 -IHW12 /2 width=1 by yle_succ/
150 >(plus_minus_m_m j 1) in ⊢ (%→?); [2: /3 width=3 by yle_trans, yle_inv_inj/ ]
151 #HnW1 @(ex3_intro … (j-1)) /3 width=9 by nlift_bind_dx, yle_pred, monotonic_pred/
153 | #I #G #L #W1 #W2 #U1 #U2 #d #e #_ #_ #IHW12 #IHU12 #i #Hdi #H elim (nlift_inv_flat … H) -H
154 [ #HnW2 elim (IHW12 … HnW2) -IHW12 -HnW2 -IHU12 //
155 #j #Hdj #Hji #HnW1 @(ex3_intro … j) /3 width=8 by nlift_flat_sn/
156 | #HnU2 elim (IHU12 … HnU2) -IHU12 -HnU2 -IHW12 //
157 #j #Hdj #Hji #HnW1 @(ex3_intro … j) /3 width=8 by nlift_flat_dx/
162 axiom frees_fwd_nlift_ge: ∀L,U,d,i. (L ⊢ i ~ϵ 𝐅*[d]⦃U⦄ → ⊥) → d ≤ yinj i →
163 ∃∃j. d ≤ yinj j & j ≤ i & (∀T. ⇧[j, 1] T ≡ U → ⊥).
166 lemma frees_ind_nlift: ∀L,d. ∀R:relation2 term nat.
167 (∀U1,i. d ≤ yinj i → (∀T1. ⇧[i, 1] T1 ≡ U1 → ⊥) → R U1 i) →
168 (∀U1,U2,i,j. d ≤ yinj j → j ≤ i → ⦃⋆, L⦄ ⊢ U1 ▶[d, ∞] U2 → (∀T2. ⇧[i, 1] T2 ≡ U2 → ⊥) → R U2 i → R U1 j) →
169 ∀U,i. d ≤ yinj i → (L ⊢ i ~ϵ 𝐅*[d]⦃U⦄ → ⊥) → R U i.
170 #L #d #R #IH1 #IH2 #U1 #i #Hdi #H @(frees_ind … H) -U1 /3 width=4 by/
171 #U1 #U2 #HU12 #HnU2 #HU2 @(IH2 … HU12 … HU2)
175 lemma frees_fwd_nlift: ∀L,d. ∀R:relation2 term nat. (
176 ∀U1,j. (∀T1. ⇧[j, 1] T1 ≡ U1 → ⊥) ∨
177 (∃∃U2,i. d ≤ yinj j → j < i & (L ⊢ j ~ϵ 𝐅*[d]⦃U1⦄ → ⊥) & ⦃⋆, L⦄ ⊢ U1 ▶[d, ∞] U2 & R U1 i
181 ∀U,i. d ≤ yinj i → (L ⊢ i ~ϵ 𝐅*[d]⦃U⦄ → ⊥) → R U i.
182 #L #d #R #IHR #U1 #j #Hdj #H elim (frees_inv_gen … H) -H
183 #U2 #H generalize in match Hdj; -Hdj generalize in match j; -j @(cpys_ind … H) -U2
184 [ #j #Hdj #HnU1 @IHR -IHR /3 width=2 by or_introl/
185 | #U0 #U2 #HU10 #HU02 #IHU10 #j #Hdj #HnU2 elim (cpy_inv_nlift2_ge … HU02 … Hdj HnU2) -HU02 -HnU2
186 #i #Hdi #Hij #HnU0 lapply (IHU10 … HnU0) // -IHU10
187 #Hi @IHR -IHR // -Hdj @or_intror
189 lemma frees_fwd_nlift: ∀L,U,d,i. d ≤ yinj i → (L ⊢ i ~ϵ 𝐅*[d]⦃U⦄ → ⊥) →
190 ∃∃j. d ≤ yinj j & j ≤ i & (∀T. ⇧[j, 1] T ≡ U → ⊥).
192 #U2 #H #HnU2 @(cpys_ind_dx … H) -U1 [ @(ex3_intro … i) /2 width=2 by/ ] -Hdi -HnU2
193 #U1 #U0 #HU10 #_ * #j #Hdj #Hji #HnU0 elim (cpy_inv_nlift2_ge … HU10 … Hdj HnU0) -U0 -Hdj
194 /3 width=5 by transitive_le, ex3_intro/
198 theorem llpx_sn_llpx_sn_alt2: ∀R,L1,L2,T,d. llpx_sn R d T L1 L2 → llpx_sn_alt2 R d T L1 L2.
199 #R #L1 #L2 #U1 #d #H elim (llpx_sn_inv_alt1 … H) -H
200 #HL12 #IH @conj // -HL12
201 #I1 #I2 #K1 #K2 #V1 #V2 #i #Hdi #H #HLK1 #HLK2
202 elim (frees_fwd_nlift_ge … H Hdi) -H -Hdi #j #Hdj #Hji #HnU1
203 lapply (ldrop_fwd_length_lt2 … HLK1) #HL1
204 lapply (ldrop_fwd_length_lt2 … HLK2) #HL2
205 lapply (le_to_lt_to_lt … Hji HL1) -HL1 #HL1
206 lapply (le_to_lt_to_lt … Hji HL2) -HL2 #HL2
207 elim (ldrop_O1_lt L1 j) // #Z1 #Y1 #X1 #HLY1
208 elim (ldrop_O1_lt L2 j) // #Z2 #Y2 #X2 #HLY2
213 generalize in match V2; -V2 generalize in match V1; -V1
214 generalize in match K2; -K2 generalize in match K1; -K1
215 generalize in match I2; -I2 generalize in match I1; -I1
216 generalize in match IH; -IH
217 @(frees_ind_nlift … Hdi H) -U1 -i
218 [ #U1 #i #Hdi #HnU1 #IH #I1 #I2 #K1 #K2 #V1 #V2 #HLK1 #HLK2 elim (IH … HnU1 HLK1 HLK2) -IH -HnU1 -HLK1 -HLK2 /2 width=1 by conj/
219 | #U1 #U2 #i #j #Hdj #Hji #HU12 #HnU2 #IHU12 #IH #I1 #I2 #K1 #K2 #V1 #V2 #HLK1 #HLK2
222 @(IHU12) … HLK1 HLK2)
224 @(IHU12 … HLK1 HLK2) -IHU02 -I1 -I2 -K1 -K2 -V1 -V2
225 #I1 #I2 #K1 #K2 #V1 #V2 #j #Hdj #HnU0 #HLK1 #HLK2 @(IH … HLK1 HLK2) -IH -HLK1 -HLK2 //
229 elim (frees_fwd_nlift … HnU1) // -HnU1 -Hdi
231 lapply (ldrop_fwd_length_lt2 … HLK1) #HL1
232 lapply (ldrop_fwd_length_lt2 … HLK2) #HL2
233 lapply (le_to_lt_to_lt … Hji HL1) -HL1 #HL1
234 lapply (le_to_lt_to_lt … Hji HL2) -HL2 #HL2
235 elim (ldrop_O1_lt L1 j) // #Z1 #Y1 #X1 #HLY1
236 elim (ldrop_O1_lt L2 j) // #Z2 #Y2 #X2 #HLY2
237 elim (IH … HnU1 HLY1 HLY2) // #H #HX12 #HY12 destruct
260 theorem llpx_sn_llpx_sn_alt2: ∀R,L1,L2,T,d. llpx_sn R d T L1 L2 → llpx_sn_alt2 R d T L1 L2.
261 #R #L1 #L2 #U1 #d #H @(llpx_sn_ind_alt1 … H) -L1 -L2 -U1 -d
262 #L1 #L2 #U1 #d #HL12 #IH @conj // -HL12
263 #I1 #I2 #K1 #K2 #V1 #V2 #i #Hdi #HnU1 #HLK1 #HLK2 elim (frees_inv_gen … HnU1) -HnU1
264 #U2 #H generalize in match IH; -IH @(cpys_ind_dx … H) -U1
265 [ #IH #HnU2 elim (IH … HnU2 … HLK1 HLK2) -L1 -L2 -U2 /2 width=1 by conj/
266 | #U1 #U0 #HU10 #_ #IHU02 #IH #HnU2 @IHU02 /2 width=2 by/ -I1 -I2 -K1 -K2 -V1 -V2 -U2 -i
267 #I1 #I2 #K1 #K2 #V1 #V2 #i #Hdi #HnU0 #HLK1 #HLK2 @(IH … HLK1 HLK2) -IH // -R -I2 -L2 -K2 -V2
268 @(cpy_inv_nlift2_be … HU10) /2 width=3 by/
270 theorem llpx_sn_llpx_sn_alt2: ∀R,L1,L2,T2,d. llpx_sn R d T2 L1 L2 →
271 ∀T1. ⦃⋆, L1⦄ ⊢ T1 ▶*[d, ∞] T2 → llpx_sn_alt2 R d T1 L1 L2.
272 #R #L1 #L2 #U2 #d #H elim (llpx_sn_inv_alt1 … H) -H
273 #HL12 #IH #U1 #HU12 @conj // -HL12
274 #I1 #I2 #K1 #K2 #V1 #V2 #i #Hdi #HnU1 #HLK1 #HLK2 elim (frees_inv_gen … HnU1) -HnU1
275 #U2 #H generalize in match IH; -IH @(cpys_ind_dx … H) -U1
276 [ #IH #HnU2 elim (IH … HnU2 … HLK1 HLK2) -L1 -L2 -U2 /2 width=1 by conj/
277 | #U1 #U0 #HU10 #_ #IHU02 #IH #HnU2 @IHU02 /2 width=2 by/ -I1 -I2 -K1 -K2 -V1 -V2 -U2 -i
278 #I1 #I2 #K1 #K2 #V1 #V2 #i #Hdi #HnU0 #HLK1 #HLK2 @(IH … HLK1 HLK2) -IH // -R -I2 -L2 -K2 -V2
279 @(cpy_inv_nlift2_be … HU10) /2 width=3 by/
282 theorem llpx_sn_llpx_sn_alt2: ∀R,L1,L2,T,d. llpx_sn R d T L1 L2 → llpx_sn_alt2 R d T L1 L2.
283 #R #L1 #L2 #U1 #d #H elim (llpx_sn_inv_alt1 … H) -H
284 #HL12 #IH @conj // -HL12
285 #I1 #I2 #K1 #K2 #V1 #V2 #i #Hdi #HnU1 #HLK1 #HLK2 elim (frees_inv_gen … HnU1) -HnU1
286 #U2 #H generalize in match IH; -IH @(cpys_ind_dx … H) -U1
287 [ #IH #HnU2 elim (IH … HnU2 … HLK1 HLK2) -L1 -L2 -U2 /2 width=1 by conj/
288 | #U1 #U0 #HU10 #_ #IHU02 #IH #HnU2 @IHU02 /2 width=2 by/ -I1 -I2 -K1 -K2 -V1 -V2 -U2 -i
289 #I1 #I2 #K1 #K2 #V1 #V2 #i #Hdi #HnU0 #HLK1 #HLK2 @(IH … HLK1 HLK2) -IH // -R -I2 -L2 -K2 -V2
290 @(cpy_inv_nlift2_be … HU10) /2 width=3 by/