2 ||M|| This file is part of HELM, an Hypertextual, Electronic
3 ||A|| Library of Mathematics, developed at the Computer Science
4 ||T|| Department of the University of Bologna, Italy.
7 ||A|| This file is distributed under the terms of the
8 \ / GNU General Public License Version 2
10 V_______________________________________________________________ *)
12 include "lambda-delta/substitution/lift_fun.ma".
13 include "lambda-delta/substitution/lift_weight.ma".
14 include "lambda-delta/reduction/tpr_main.ma".
15 include "lambda-delta/reduction/tpr_ps.ma".
17 (* CONTEXT-FREE PARALLEL REDUCTION ON TERMS *********************************)
19 (* Confluence lemmas ********************************************************)
21 lemma tpr_conf_sort_sort: ∀k. ∃∃X. ⋆k ⇒ X & ⋆k ⇒ X.
24 lemma tpr_conf_lref_lref: ∀i. ∃∃X. #i ⇒ X & #i ⇒ X.
27 lemma tpr_conf_bind_bind:
28 ∀I,V0,V1,T0,T1,V2,T2. (
29 ∀X0:term. #X0 < #V0 + #T0 + 1 →
30 ∀X1,X2. X0 ⇒ X1 → X0 ⇒ X2 →
33 V0 ⇒ V1 → V0 ⇒ V2 → T0 ⇒ T1 → T0 ⇒ T2 →
34 ∃∃X. 𝕓{I} V1. T1 ⇒ X & 𝕓{I} V2. T2 ⇒ X.
35 #I #V0 #V1 #T0 #T1 #V2 #T2 #IH #HV01 #HV02 #HT01 #HT02
36 elim (IH … HV01 … HV02) -HV01 HV02 // #V #HV1 #HV2
37 elim (IH … HT01 … HT02) -HT01 HT02 IH /3 width=5/
40 lemma tpr_conf_bind_delta:
41 ∀V0,V1,T0,T1,V2,T2,T. (
42 ∀X0:term. #X0 < #V0 + #T0 + 1 →
43 ∀X1,X2. X0 ⇒ X1 → X0 ⇒ X2 →
47 T0 ⇒ T1 → T0 ⇒ T2 → ⋆. 𝕓{Abbr} V2 ⊢ T2 [O,1] ≫ T →
48 ∃∃X. 𝕓{Abbr} V1. T1 ⇒ X & 𝕓{Abbr} V2. T ⇒ X.
49 #V0 #V1 #T0 #T1 #V2 #T2 #T #IH #HV01 #HV02 #HT01 #HT02 #HT2
50 elim (IH … HV01 … HV02) -HV01 HV02 // #V #HV1 #HV2
51 elim (IH … HT01 … HT02) -HT01 HT02 IH // -V0 T0 #T0 #HT10 #HT20
52 elim (tpr_ps_bind … HV2 HT20 … HT2) -HT20 HT2 /3 width=5/
55 lemma tpr_conf_bind_zeta:
57 ∀X0:term. #X0 < #V0 + #T0 +1 →
58 ∀X1,X2. X0 ⇒ X1 → X0 ⇒ X2 →
61 V0 ⇒ V1 → T0 ⇒ T1 → T ⇒ X2 → ↑[O, 1] T ≡ T0 →
62 ∃∃X. 𝕓{Abbr} V1. T1 ⇒ X & X2 ⇒ X.
63 #X2 #V0 #V1 #T0 #T1 #T #IH #HV01 #HT01 #HTX2 #HT0
64 elim (tpr_inv_lift … HT01 … HT0) -HT01 #U #HUT1 #HTU
65 lapply (tw_lift … HT0) -HT0 #HT0
66 elim (IH … HTX2 … HTU) -HTX2 HTU IH /3/
69 lemma tpr_conf_flat_flat:
70 ∀I,V0,V1,T0,T1,V2,T2. (
71 ∀X0:term. #X0 < #V0 + #T0 + 1 →
72 ∀X1,X2. X0 ⇒ X1 → X0 ⇒ X2 →
75 V0 ⇒ V1 → V0 ⇒ V2 → T0 ⇒ T1 → T0 ⇒ T2 →
76 ∃∃T0. 𝕗{I} V1. T1 ⇒ T0 & 𝕗{I} V2. T2 ⇒ T0.
77 #I #V0 #V1 #T0 #T1 #V2 #T2 #IH #HV01 #HV02 #HT01 #HT02
78 elim (IH … HV01 … HV02) -HV01 HV02 // #V #HV1 #HV2
79 elim (IH … HT01 … HT02) -HT01 HT02 /3 width=5/
82 lemma tpr_conf_flat_beta:
83 ∀V0,V1,T1,V2,W0,U0,T2. (
84 ∀X0:term. #X0 < #V0 + (#W0 + #U0 + 1) + 1 →
85 ∀X1,X2. X0 ⇒ X1 → X0 ⇒ X2 →
89 U0 ⇒ T2 → 𝕓{Abst} W0. U0 ⇒ T1 →
90 ∃∃X. 𝕗{Appl} V1. T1 ⇒ X & 𝕓{Abbr} V2. T2 ⇒ X.
91 #V0 #V1 #T1 #V2 #W0 #U0 #T2 #IH #HV01 #HV02 #HT02 #H
92 elim (tpr_inv_abst1 … H) -H #W1 #U1 #HW01 #HU01 #H destruct -T1;
93 elim (IH … HV01 … HV02) -HV01 HV02 // #V #HV1 #HV2
94 elim (IH … HT02 … HU01) -HT02 HU01 IH /3 width=5/
97 lemma tpr_conf_flat_theta:
98 ∀V0,V1,T1,V2,V,W0,W2,U0,U2. (
99 ∀X0:term. #X0 < #V0 + (#W0 + #U0 + 1) + 1 →
100 ∀X1,X2. X0 ⇒ X1 → X0 ⇒ X2 →
103 V0 ⇒ V1 → V0 ⇒ V2 → ↑[O,1] V2 ≡ V →
104 W0 ⇒ W2 → U0 ⇒ U2 → 𝕓{Abbr} W0. U0 ⇒ T1 →
105 ∃∃X. 𝕗{Appl} V1. T1 ⇒ X & 𝕓{Abbr} W2. 𝕗{Appl} V. U2 ⇒ X.
106 #V0 #V1 #T1 #V2 #V #W0 #W2 #U0 #U2 #IH #HV01 #HV02 #HV2 #HW02 #HU02 #H
107 elim (IH … HV01 … HV02) -HV01 HV02 // #VV #HVV1 #HVV2
108 elim (lift_total VV 0 1) #VVV #HVV
109 lapply (tpr_lift … HVV2 … HV2 … HVV) #HVVV
110 elim (tpr_inv_abbr1 … H) -H *
112 [ -HV2 HVV2 #WW #UU #HWW0 #HUU0 #H destruct -T1;
113 elim (IH … HW02 … HWW0) -HW02 HWW0 // #W #HW2 #HWW
114 elim (IH … HU02 … HUU0) -HU02 HUU0 IH // #U #HU2 #HUU
116 [2: @tpr_theta [5: @HVV1 |6: @HVV |7:// by {}; (*@HWW*) |8: @HUU |1,2,3,4:skip ]
117 |3: @tpr_bind [ @HW2 | @tpr_flat [ @HVVV | @HU2 ] ]
119 (* Confluence ***************************************************************)
123 ∀X0:term. #X0 < #Y0 → ∀X1,X2. X0 ⇒ X1 → X0 ⇒ X2 →
126 ∀X0,X1,X2. X0 ⇒ X1 → X0 ⇒ X2 → X0 = Y0 →
127 ∃∃X. X1 ⇒ X & X2 ⇒ X.
128 #Y0 #IH #X0 #X1 #X2 * -X0 X1
129 [ #k1 #H1 #H2 destruct -Y0;
130 lapply (tpr_inv_sort1 … H1) -H1
131 (* case 1: sort, sort *)
133 | #i1 #H1 #H2 destruct -Y0;
134 lapply (tpr_inv_lref1 … H1) -H1
135 (* case 2: lref, lref *)
137 | #I #V0 #V1 #T0 #T1 #HV01 #HT01 #H1 #H2 destruct -Y0;
138 elim (tpr_inv_bind1 … H1) -H1 *
139 (* case 3: bind, bind *)
140 [ #V2 #T2 #HV02 #HT02 #H destruct -X2
141 @tpr_conf_bind_bind /2 width=7/ (**) (* /3 width=7/ is too slow *)
142 (* case 4: bind, delta *)
143 | #V2 #T2 #T #HV02 #HT02 #HT2 #H1 #H2 destruct -X2 I
144 @tpr_conf_bind_delta /2 width=9/ (**) (* /3 width=9/ is too slow *)
145 (* case 5: bind, zeta *)
146 | #T #HT0 #HTX2 #H destruct -I
147 @tpr_conf_bind_zeta /2 width=8/ (**) (* /3 width=8/ is too slow *)
149 | #I #V0 #V1 #T0 #T1 #HV01 #HT01 #H1 #H2 destruct -Y0;
150 elim (tpr_inv_flat1 … H1) -H1 *
151 (* case 6: flat, flat *)
152 [ #V2 #T2 #HV02 #HT02 #H destruct -X2
153 @tpr_conf_flat_flat /2 width=7/ (**) (* /3 width=7/ is too slow *)
154 (* case 7: flat, beta *)
155 | #V2 #W #U0 #T2 #HV02 #HT02 #H1 #H2 #H3 destruct -T0 X2 I
156 @tpr_conf_flat_beta /2 width=8/ (**) (* /3 width=8/ is too slow *)
157 (* case 8: flat, theta *)
158 | #V2 #V #W0 #W2 #U0 #U2 #HV02 #HW02 #HT02 #HV2 #H1 #H2 #H3 destruct -T0 X2 I
160 theorem tpr_conf: ∀T0,T1,T2. T0 ⇒ T1 → T0 ⇒ T2 →
161 ∃∃T. T1 ⇒ T & T2 ⇒ T.
162 #T @(tw_wf_ind … T) -T /3 width=6/
167 ∀T1. #T1 < #T → ∀T3,T4. T1 ⇒ T3 → T1 ⇒ T4 →
168 ∃∃T0. T3 ⇒ T0 & T4 ⇒ T0
170 ∀U1,T1,U2,T2. U1 ⇒ T1 → U2 ⇒ T2 →
172 ∃∃T0. T1 ⇒ T0 & T2 ⇒ T0.
173 #T #IH #U1 #T1 #U2 #T2
176 (* case 1: sort, sort *)
177 [ #k2 #H1 #H2 destruct -T k2 //
178 (* case 2: sort, lref (excluded) *)
179 | #i2 #H1 #H2 destruct
180 (* case 3: sort, bind (excluded) *)
181 | #I2 #V21 #V22 #T21 #T22 #_ #_ #H1 #H2 destruct
182 (* case 4: sort, flat (excluded) *)
183 | #I2 #V21 #V22 #T21 #T22 #_ #_ #H1 #H2 destruct
184 (* case 5: sort, beta (excluded) *)
185 | #V21 #V22 #W2 #T21 #T22 #_ #_ #H1 #H2 destruct
186 (* case 6: sort, delta (excluded) *)
187 | #V21 #V22 #T21 #T22 #T20 #_ #_ #_ #H1 #H2 destruct
188 (* case 7: sort, theta (excluded) *)
189 | #V2 #V21 #V22 #W21 #W22 #T21 #T22 #_ #_ #_ #_ #H1 #H2 destruct
190 (* case 8: sort, zeta (excluded) *)
191 | #V2 #T21 #T22 #T20 #_ #_ #H1 #H2 destruct
192 (* case 9: sort, tau (excluded) *)
193 | #V2 #T21 #T22 #_ #H1 #H2 destruct
196 (* case 10: lref, sort (excluded) broken *)
197 [ #k2 #H1 #H2 destruct
198 (* case 11: lref, sort (excluded) *)
199 | #i2 #H1 #H2 destruct -T i2 //
200 (* case 12: lref, bind (excluded) *)
201 | #I2 #V21 #V22 #T21 #T22 #_ #_ #H1 #H2 destruct
202 (* case 13: lref, flat (excluded) *)
203 | #I2 #V21 #V22 #T21 #T22 #_ #_ #H1 #H2 destruct
204 (* case 14: lref, beta (excluded) *)
205 | #V21 #V22 #W2 #T21 #T22 #_ #_ #H1 #H2 destruct
206 (* case 15: lref, delta (excluded) *)
207 | #V21 #V22 #T21 #T22 #T20 #_ #_ #_ #H1 #H2 destruct
208 (* case 16: lref, theta (excluded) *)
209 | #V2 #V21 #V22 #W21 #W22 #T21 #T22 #_ #_ #_ #_ #H1 #H2 destruct
210 (* case 17: lref, zeta (excluded) *)
211 | #V2 #T21 #T22 #T20 #_ #_ #H1 #H2 destruct
212 (* case 18: lref, tau (excluded) *)
213 | #V2 #T21 #T22 #_ #H1 #H2 destruct
215 | #I1 #V11 #V12 #T11 #T12 #HV112 #HT112 * -U2 T2
216 (* case 19: bind, sort (excluded) *)
217 [ #k2 #H1 #H2 destruct
218 (* case 20: bind, lref (excluded) *)
219 | #i2 #H1 #H2 destruct
220 (* case 21: bind, bind *)
221 | #I2 #V21 #V22 #T21 #T22 #HV212 #HT212 #H1 #H2
222 destruct -T I2 V21 T21 /3 width=7/
223 (* case 22: bind, flat (excluded) *)
224 | #I2 #V21 #V22 #T21 #T22 #_ #_ #H1 #H2 destruct
225 (* case 23: bind, beta (excluded) *)
226 | #V21 #V22 #W2 #T21 #T22 #_ #_ #H1 #H2 destruct
227 (* case 24: bind, delta (excluded) *)
228 | #V21 #V22 #T21 #T22 #T20 #_ #_ #_ #H1 #H2 destruct
229 (* case 25: bind, theta (excluded) *)
230 | #V2 #V21 #V22 #W21 #W22 #T21 #T22 #_ #_ #_ #_ #H1 #H2 destruct
231 (* case 26: bind, zeta *)
232 | #V2 #T21 #T22 #T20 #HT212 #HT220 #H1 #H2
233 destruct -I1 V2 T21 T /3 width=8/
234 (* case 27: bind, tau (excluded) *)
235 | #V2 #T21 #T22 #_ #H1 #H2 destruct
237 | #I1 #V11 #V12 #T11 #T12 #HV112 #HT112 * -U2 T2
238 (* case 28: flat, sort (excluded) *)
239 [ #k2 #H1 #H2 destruct
240 (* case 29: flat, lref (excluded) *)
241 | #i2 #H1 #H2 destruct
242 (* case 30: flat, bind (excluded) *)
243 | #I2 #V21 #V22 #T21 #T22 #_ #_ #H1 #H2 destruct
244 (* case 31: flat, flat *)
245 | #I2 #V21 #V22 #T21 #T22 #HV212 #HT212 #H1 #H2
246 destruct -T I2 V21 T21 /3 width=7/
247 (* case 32: flat, beta *)
248 | #V21 #V22 #W2 #T21 #T22 #HV212 #HT212 #H1 #H2
249 destruct -I1 V21 T11 T /3 width=8/ (**) (* slow *)
250 (* case 33: flat, delta (excluded) *)
251 | #V21 #V22 #T21 #T22 #T20 #_ #_ #_ #H1 #H2 destruct
252 (* case 34: flat, theta *)
253 | #V2 #V21 #V22 #W21 #W22 #T21 #T22 #H212 #HV222 #HW212 #HT212 #H1 #H2
254 destruct -I1 V21 T11 T //
256 lemma tpr_conf_flat_theta:
257 ∀V11,V12,T12,V2,V22,W21,W22,T21,T22. (
258 ∀T1. #T1 < #V11 + (#W21 + #T21 + 1) + 1 →
259 ∀T3,T4. T1 ⇒ T3 → T1 ⇒ T4 →
260 ∃∃T0. T3 ⇒ T0 & T4 ⇒T0
262 V11 ⇒ V12 → V11 ⇒ V22 → ↑[O,1] V22 ≡ V2 →
263 W21 ⇒ W22 → T21 ⇒ T22 → 𝕓{Abbr} W21. T21 ⇒ T12 →
264 ∃∃T0. 𝕗{Appl} V12. T12 ⇒ T0 & 𝕓{Abbr} W22. 𝕗{Appl} V2. T22 ⇒T0.
266 lemma tpr_conf_bind_delta:
267 ∀V0,V1,T0,T1,V2,T2,T. (
268 ∀X. #X < #V0 + #T0 + 1 →
269 ∀X1,X2. X0 ⇒ X1 → X0 ⇒ X2 →
273 T0 ⇒ T1 → T0 ⇒ T2 → ⋆. 𝕓{Abbr} V2 ⊢ T2 [O,1] ≫ T →
274 ∃∃X. 𝕓{Abbr} V1. T1 ⇒ X & 𝕓{Abbr} V2. T ⇒ X.