1 (**************************************************************************)
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 *)
13 (**************************************************************************)
15 include "ground/xoa/ex_4_1.ma".
16 include "ground/xoa/ex_5_6.ma".
17 include "ground/xoa/ex_6_6.ma".
18 include "ground/xoa/ex_6_7.ma".
19 include "ground/xoa/ex_7_7.ma".
20 include "ground/xoa/or_4.ma".
21 include "basic_2A/notation/relations/pred_4.ma".
22 include "basic_2A/static/lsubr.ma".
23 include "basic_2A/unfold/lstas.ma".
25 (* CONTEXT-SENSITIVE PARALLEL REDUCTION FOR TERMS ***************************)
28 (* Note: cpr_flat: does not hold in basic_1 *)
29 inductive cpr: relation4 genv lenv term term ≝
30 | cpr_atom : ∀I,G,L. cpr G L (⓪{I}) (⓪{I})
31 | cpr_delta: ∀G,L,K,V,V2,W2,i.
32 ⬇[i] L ≡ K. ⓓV → cpr G K V V2 →
33 ⬆[0, i + 1] V2 ≡ W2 → cpr G L (#i) W2
34 | cpr_bind : ∀a,I,G,L,V1,V2,T1,T2.
35 cpr G L V1 V2 → cpr G (L.ⓑ{I}V1) T1 T2 →
36 cpr G L (ⓑ{a,I}V1.T1) (ⓑ{a,I}V2.T2)
37 | cpr_flat : ∀I,G,L,V1,V2,T1,T2.
38 cpr G L V1 V2 → cpr G L T1 T2 →
39 cpr G L (ⓕ{I}V1.T1) (ⓕ{I}V2.T2)
40 | cpr_zeta : ∀G,L,V,T1,T,T2. cpr G (L.ⓓV) T1 T →
41 ⬆[0, 1] T2 ≡ T → cpr G L (+ⓓV.T1) T2
42 | cpr_eps : ∀G,L,V,T1,T2. cpr G L T1 T2 → cpr G L (ⓝV.T1) T2
43 | cpr_beta : ∀a,G,L,V1,V2,W1,W2,T1,T2.
44 cpr G L V1 V2 → cpr G L W1 W2 → cpr G (L.ⓛW1) T1 T2 →
45 cpr G L (ⓐV1.ⓛ{a}W1.T1) (ⓓ{a}ⓝW2.V2.T2)
46 | cpr_theta: ∀a,G,L,V1,V,V2,W1,W2,T1,T2.
47 cpr G L V1 V → ⬆[0, 1] V ≡ V2 → cpr G L W1 W2 → cpr G (L.ⓓW1) T1 T2 →
48 cpr G L (ⓐV1.ⓓ{a}W1.T1) (ⓓ{a}W2.ⓐV2.T2)
51 interpretation "context-sensitive parallel reduction (term)"
52 'PRed G L T1 T2 = (cpr G L T1 T2).
54 (* Basic properties *********************************************************)
56 lemma lsubr_cpr_trans: ∀G. lsub_trans … (cpr G) lsubr.
57 #G #L1 #T1 #T2 #H elim H -G -L1 -T1 -T2
59 | #G #L1 #K1 #V1 #V2 #W2 #i #HLK1 #_ #HVW2 #IHV12 #L2 #HL12
60 elim (lsubr_fwd_drop2_abbr … HL12 … HLK1) -L1 *
61 /3 width=6 by cpr_delta/
62 |3,7: /4 width=1 by lsubr_pair, cpr_bind, cpr_beta/
63 |4,6: /3 width=1 by cpr_flat, cpr_eps/
64 |5,8: /4 width=3 by lsubr_pair, cpr_zeta, cpr_theta/
68 lemma tpr_cpr: ∀G,T1,T2. ⦃G, ⋆⦄ ⊢ T1 ➡ T2 → ∀L. ⦃G, L⦄ ⊢ T1 ➡ T2.
70 lapply (lsubr_cpr_trans … HT12 L ?) //
73 lemma cpr_refl: ∀G,T,L. ⦃G, L⦄ ⊢ T ➡ T.
74 #G #T elim T -T // * /2 width=1 by cpr_bind, cpr_flat/
77 lemma cpr_pair_sn: ∀I,G,L,V1,V2. ⦃G, L⦄ ⊢ V1 ➡ V2 →
78 ∀T. ⦃G, L⦄ ⊢ ②{I}V1.T ➡ ②{I}V2.T.
79 * /2 width=1 by cpr_bind, cpr_flat/ qed.
81 lemma cpr_delift: ∀G,K,V,T1,L,l. ⬇[l] L ≡ (K.ⓓV) →
82 ∃∃T2,T. ⦃G, L⦄ ⊢ T1 ➡ T2 & ⬆[l, 1] T ≡ T2.
83 #G #K #V #T1 elim T1 -T1
84 [ * /2 width=4 by cpr_atom, lift_sort, lift_gref, ex2_2_intro/
85 #i #L #l #HLK elim (lt_or_eq_or_gt i l)
86 #Hil [1,3: /3 width=4 by cpr_atom, lift_lref_ge_minus, lift_lref_lt, ex2_2_intro/ ]
88 elim (lift_total V 0 (i+1)) #W #HVW
89 elim (lift_split … HVW i i) /3 width=6 by cpr_delta, ex2_2_intro/
90 | * [ #a ] #I #W1 #U1 #IHW1 #IHU1 #L #l #HLK
91 elim (IHW1 … HLK) -IHW1 #W2 #W #HW12 #HW2
92 [ elim (IHU1 (L. ⓑ{I}W1) (l+1)) -IHU1 /3 width=9 by drop_drop, cpr_bind, lift_bind, ex2_2_intro/
93 | elim (IHU1 … HLK) -IHU1 -HLK /3 width=8 by cpr_flat, lift_flat, ex2_2_intro/
98 fact lstas_cpr_aux: ∀h,G,L,T1,T2,d. ⦃G, L⦄ ⊢ T1 •*[h, d] T2 →
99 d = 0 → ⦃G, L⦄ ⊢ T1 ➡ T2.
100 #h #G #L #T1 #T2 #d #H elim H -G -L -T1 -T2 -d
101 /3 width=1 by cpr_eps, cpr_flat, cpr_bind/
102 [ #G #L #K #V1 #V2 #W2 #i #d #HLK #_ #HVW2 #IHV12 #H destruct
103 /3 width=6 by cpr_delta/
104 | #G #L #K #V1 #V2 #W2 #i #d #_ #_ #_ #_ <plus_n_Sm #H destruct
108 lemma lstas_cpr: ∀h,G,L,T1,T2. ⦃G, L⦄ ⊢ T1 •*[h, 0] T2 → ⦃G, L⦄ ⊢ T1 ➡ T2.
109 /2 width=4 by lstas_cpr_aux/ qed.
111 (* Basic inversion lemmas ***************************************************)
113 fact cpr_inv_atom1_aux: ∀G,L,T1,T2. ⦃G, L⦄ ⊢ T1 ➡ T2 → ∀I. T1 = ⓪{I} →
115 ∃∃K,V,V2,i. ⬇[i] L ≡ K. ⓓV & ⦃G, K⦄ ⊢ V ➡ V2 &
116 ⬆[O, i + 1] V2 ≡ T2 & I = LRef i.
117 #G #L #T1 #T2 * -G -L -T1 -T2
118 [ #I #G #L #J #H destruct /2 width=1 by or_introl/
119 | #L #G #K #V #V2 #T2 #i #HLK #HV2 #HVT2 #J #H destruct /3 width=8 by ex4_4_intro, or_intror/
120 | #a #I #G #L #V1 #V2 #T1 #T2 #_ #_ #J #H destruct
121 | #I #G #L #V1 #V2 #T1 #T2 #_ #_ #J #H destruct
122 | #G #L #V #T1 #T #T2 #_ #_ #J #H destruct
123 | #G #L #V #T1 #T2 #_ #J #H destruct
124 | #a #G #L #V1 #V2 #W1 #W2 #T1 #T2 #_ #_ #_ #J #H destruct
125 | #a #G #L #V1 #V #V2 #W1 #W2 #T1 #T2 #_ #_ #_ #_ #J #H destruct
129 lemma cpr_inv_atom1: ∀I,G,L,T2. ⦃G, L⦄ ⊢ ⓪{I} ➡ T2 →
131 ∃∃K,V,V2,i. ⬇[i] L ≡ K. ⓓV & ⦃G, K⦄ ⊢ V ➡ V2 &
132 ⬆[O, i + 1] V2 ≡ T2 & I = LRef i.
133 /2 width=3 by cpr_inv_atom1_aux/ qed-.
135 lemma cpr_inv_sort1: ∀G,L,T2,k. ⦃G, L⦄ ⊢ ⋆k ➡ T2 → T2 = ⋆k.
137 elim (cpr_inv_atom1 … H) -H //
138 * #K #V #V2 #i #_ #_ #_ #H destruct
141 lemma cpr_inv_lref1: ∀G,L,T2,i. ⦃G, L⦄ ⊢ #i ➡ T2 →
143 ∃∃K,V,V2. ⬇[i] L ≡ K. ⓓV & ⦃G, K⦄ ⊢ V ➡ V2 &
146 elim (cpr_inv_atom1 … H) -H /2 width=1 by or_introl/
147 * #K #V #V2 #j #HLK #HV2 #HVT2 #H destruct /3 width=6 by ex3_3_intro, or_intror/
150 lemma cpr_inv_gref1: ∀G,L,T2,p. ⦃G, L⦄ ⊢ §p ➡ T2 → T2 = §p.
152 elim (cpr_inv_atom1 … H) -H //
153 * #K #V #V2 #i #_ #_ #_ #H destruct
156 fact cpr_inv_bind1_aux: ∀G,L,U1,U2. ⦃G, L⦄ ⊢ U1 ➡ U2 →
157 ∀a,I,V1,T1. U1 = ⓑ{a,I}V1. T1 → (
158 ∃∃V2,T2. ⦃G, L⦄ ⊢ V1 ➡ V2 & ⦃G, L.ⓑ{I}V1⦄ ⊢ T1 ➡ T2 &
161 ∃∃T. ⦃G, L.ⓓV1⦄ ⊢ T1 ➡ T & ⬆[0, 1] U2 ≡ T &
163 #G #L #U1 #U2 * -L -U1 -U2
164 [ #I #G #L #b #J #W1 #U1 #H destruct
165 | #L #G #K #V #V2 #W2 #i #_ #_ #_ #b #J #W #U1 #H destruct
166 | #a #I #G #L #V1 #V2 #T1 #T2 #HV12 #HT12 #b #J #W #U1 #H destruct /3 width=5 by ex3_2_intro, or_introl/
167 | #I #G #L #V1 #V2 #T1 #T2 #_ #_ #b #J #W #U1 #H destruct
168 | #G #L #V #T1 #T #T2 #HT1 #HT2 #b #J #W #U1 #H destruct /3 width=3 by ex4_intro, or_intror/
169 | #G #L #V #T1 #T2 #_ #b #J #W #U1 #H destruct
170 | #a #G #L #V1 #V2 #W1 #W2 #T1 #T2 #_ #_ #_ #b #J #W #U1 #H destruct
171 | #a #G #L #V1 #V #V2 #W1 #W2 #T1 #T2 #_ #_ #_ #_ #b #J #W #U1 #H destruct
175 lemma cpr_inv_bind1: ∀a,I,G,L,V1,T1,U2. ⦃G, L⦄ ⊢ ⓑ{a,I}V1.T1 ➡ U2 → (
176 ∃∃V2,T2. ⦃G, L⦄ ⊢ V1 ➡ V2 & ⦃G, L.ⓑ{I}V1⦄ ⊢ T1 ➡ T2 &
179 ∃∃T. ⦃G, L.ⓓV1⦄ ⊢ T1 ➡ T & ⬆[0, 1] U2 ≡ T &
181 /2 width=3 by cpr_inv_bind1_aux/ qed-.
183 lemma cpr_inv_abbr1: ∀a,G,L,V1,T1,U2. ⦃G, L⦄ ⊢ ⓓ{a}V1.T1 ➡ U2 → (
184 ∃∃V2,T2. ⦃G, L⦄ ⊢ V1 ➡ V2 & ⦃G, L. ⓓV1⦄ ⊢ T1 ➡ T2 &
187 ∃∃T. ⦃G, L.ⓓV1⦄ ⊢ T1 ➡ T & ⬆[0, 1] U2 ≡ T & a = true.
188 #a #G #L #V1 #T1 #U2 #H
189 elim (cpr_inv_bind1 … H) -H *
190 /3 width=5 by ex3_2_intro, ex3_intro, or_introl, or_intror/
193 lemma cpr_inv_abst1: ∀a,G,L,V1,T1,U2. ⦃G, L⦄ ⊢ ⓛ{a}V1.T1 ➡ U2 →
194 ∃∃V2,T2. ⦃G, L⦄ ⊢ V1 ➡ V2 & ⦃G, L.ⓛV1⦄ ⊢ T1 ➡ T2 &
196 #a #G #L #V1 #T1 #U2 #H
197 elim (cpr_inv_bind1 … H) -H *
198 [ /3 width=5 by ex3_2_intro/
199 | #T #_ #_ #_ #H destruct
203 fact cpr_inv_flat1_aux: ∀G,L,U,U2. ⦃G, L⦄ ⊢ U ➡ U2 →
204 ∀I,V1,U1. U = ⓕ{I}V1.U1 →
205 ∨∨ ∃∃V2,T2. ⦃G, L⦄ ⊢ V1 ➡ V2 & ⦃G, L⦄ ⊢ U1 ➡ T2 &
207 | (⦃G, L⦄ ⊢ U1 ➡ U2 ∧ I = Cast)
208 | ∃∃a,V2,W1,W2,T1,T2. ⦃G, L⦄ ⊢ V1 ➡ V2 & ⦃G, L⦄ ⊢ W1 ➡ W2 &
209 ⦃G, L.ⓛW1⦄ ⊢ T1 ➡ T2 & U1 = ⓛ{a}W1.T1 &
210 U2 = ⓓ{a}ⓝW2.V2.T2 & I = Appl
211 | ∃∃a,V,V2,W1,W2,T1,T2. ⦃G, L⦄ ⊢ V1 ➡ V & ⬆[0,1] V ≡ V2 &
212 ⦃G, L⦄ ⊢ W1 ➡ W2 & ⦃G, L.ⓓW1⦄ ⊢ T1 ➡ T2 &
214 U2 = ⓓ{a}W2.ⓐV2.T2 & I = Appl.
215 #G #L #U #U2 * -L -U -U2
216 [ #I #G #L #J #W1 #U1 #H destruct
217 | #G #L #K #V #V2 #W2 #i #_ #_ #_ #J #W #U1 #H destruct
218 | #a #I #G #L #V1 #V2 #T1 #T2 #_ #_ #J #W #U1 #H destruct
219 | #I #G #L #V1 #V2 #T1 #T2 #HV12 #HT12 #J #W #U1 #H destruct /3 width=5 by or4_intro0, ex3_2_intro/
220 | #G #L #V #T1 #T #T2 #_ #_ #J #W #U1 #H destruct
221 | #G #L #V #T1 #T2 #HT12 #J #W #U1 #H destruct /3 width=1 by or4_intro1, conj/
222 | #a #G #L #V1 #V2 #W1 #W2 #T1 #T2 #HV12 #HW12 #HT12 #J #W #U1 #H destruct /3 width=11 by or4_intro2, ex6_6_intro/
223 | #a #G #L #V1 #V #V2 #W1 #W2 #T1 #T2 #HV1 #HV2 #HW12 #HT12 #J #W #U1 #H destruct /3 width=13 by or4_intro3, ex7_7_intro/
227 lemma cpr_inv_flat1: ∀I,G,L,V1,U1,U2. ⦃G, L⦄ ⊢ ⓕ{I}V1.U1 ➡ U2 →
228 ∨∨ ∃∃V2,T2. ⦃G, L⦄ ⊢ V1 ➡ V2 & ⦃G, L⦄ ⊢ U1 ➡ T2 &
230 | (⦃G, L⦄ ⊢ U1 ➡ U2 ∧ I = Cast)
231 | ∃∃a,V2,W1,W2,T1,T2. ⦃G, L⦄ ⊢ V1 ➡ V2 & ⦃G, L⦄ ⊢ W1 ➡ W2 &
232 ⦃G, L.ⓛW1⦄ ⊢ T1 ➡ T2 & U1 = ⓛ{a}W1.T1 &
233 U2 = ⓓ{a}ⓝW2.V2.T2 & I = Appl
234 | ∃∃a,V,V2,W1,W2,T1,T2. ⦃G, L⦄ ⊢ V1 ➡ V & ⬆[0,1] V ≡ V2 &
235 ⦃G, L⦄ ⊢ W1 ➡ W2 & ⦃G, L.ⓓW1⦄ ⊢ T1 ➡ T2 &
237 U2 = ⓓ{a}W2.ⓐV2.T2 & I = Appl.
238 /2 width=3 by cpr_inv_flat1_aux/ qed-.
240 lemma cpr_inv_appl1: ∀G,L,V1,U1,U2. ⦃G, L⦄ ⊢ ⓐV1.U1 ➡ U2 →
241 ∨∨ ∃∃V2,T2. ⦃G, L⦄ ⊢ V1 ➡ V2 & ⦃G, L⦄ ⊢ U1 ➡ T2 &
243 | ∃∃a,V2,W1,W2,T1,T2. ⦃G, L⦄ ⊢ V1 ➡ V2 & ⦃G, L⦄ ⊢ W1 ➡ W2 &
244 ⦃G, L.ⓛW1⦄ ⊢ T1 ➡ T2 &
245 U1 = ⓛ{a}W1.T1 & U2 = ⓓ{a}ⓝW2.V2.T2
246 | ∃∃a,V,V2,W1,W2,T1,T2. ⦃G, L⦄ ⊢ V1 ➡ V & ⬆[0,1] V ≡ V2 &
247 ⦃G, L⦄ ⊢ W1 ➡ W2 & ⦃G, L.ⓓW1⦄ ⊢ T1 ➡ T2 &
248 U1 = ⓓ{a}W1.T1 & U2 = ⓓ{a}W2.ⓐV2.T2.
249 #G #L #V1 #U1 #U2 #H elim (cpr_inv_flat1 … H) -H *
250 [ /3 width=5 by or3_intro0, ex3_2_intro/
252 | /3 width=11 by or3_intro1, ex5_6_intro/
253 | /3 width=13 by or3_intro2, ex6_7_intro/
257 (* Note: the main property of simple terms *)
258 lemma cpr_inv_appl1_simple: ∀G,L,V1,T1,U. ⦃G, L⦄ ⊢ ⓐV1. T1 ➡ U → 𝐒⦃T1⦄ →
259 ∃∃V2,T2. ⦃G, L⦄ ⊢ V1 ➡ V2 & ⦃G, L⦄ ⊢ T1 ➡ T2 &
261 #G #L #V1 #T1 #U #H #HT1
262 elim (cpr_inv_appl1 … H) -H *
263 [ /2 width=5 by ex3_2_intro/
264 | #a #V2 #W1 #W2 #U1 #U2 #_ #_ #_ #H #_ destruct
265 elim (simple_inv_bind … HT1)
266 | #a #V #V2 #W1 #W2 #U1 #U2 #_ #_ #_ #_ #H #_ destruct
267 elim (simple_inv_bind … HT1)
271 lemma cpr_inv_cast1: ∀G,L,V1,U1,U2. ⦃G, L⦄ ⊢ ⓝ V1. U1 ➡ U2 → (
272 ∃∃V2,T2. ⦃G, L⦄ ⊢ V1 ➡ V2 & ⦃G, L⦄ ⊢ U1 ➡ T2 &
274 ) ∨ ⦃G, L⦄ ⊢ U1 ➡ U2.
275 #G #L #V1 #U1 #U2 #H elim (cpr_inv_flat1 … H) -H *
276 [ /3 width=5 by ex3_2_intro, or_introl/
277 | /2 width=1 by or_intror/
278 | #a #V2 #W1 #W2 #T1 #T2 #_ #_ #_ #_ #_ #H destruct
279 | #a #V #V2 #W1 #W2 #T1 #T2 #_ #_ #_ #_ #_ #_ #H destruct
283 (* Basic forward lemmas *****************************************************)
285 lemma cpr_fwd_bind1_minus: ∀I,G,L,V1,T1,T. ⦃G, L⦄ ⊢ -ⓑ{I}V1.T1 ➡ T → ∀b.
286 ∃∃V2,T2. ⦃G, L⦄ ⊢ ⓑ{b,I}V1.T1 ➡ ⓑ{b,I}V2.T2 &
288 #I #G #L #V1 #T1 #T #H #b
289 elim (cpr_inv_bind1 … H) -H *
290 [ #V2 #T2 #HV12 #HT12 #H destruct /3 width=4 by cpr_bind, ex2_2_intro/
291 | #T2 #_ #_ #H destruct