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_weight.ma".
13 include "lambda-delta/reduction/tpr_main.ma".
15 (* CONTEXT-FREE PARALLEL REDUCTION ON TERMS *********************************)
17 (* Confluence lemmas ********************************************************)
19 lemma tpr_conf_sort_sort: ∀k1. ∃∃T0. ⋆k1 ⇒ T0 & ⋆k1 ⇒ T0.
22 lemma tpr_conf_lref_lref: ∀i1. ∃∃T0. #i1 ⇒ T0 & #i1 ⇒ T0.
25 lemma tpr_conf_bind_bind:
26 ∀I1,V11,V12,T11,T12,V22,T22. (
27 ∀T1. #T1 < #V11 + #T11 + 1 →
28 ∀T3,T4. T1 ⇒ T3 → T1 ⇒ T4 →
29 ∃∃T0. T3 ⇒ T0 & T4 ⇒ T0
31 V11 ⇒ V12 → T11 ⇒ T12 →
32 V11 ⇒ V22 → T11 ⇒ T22 →
33 ∃∃T0. 𝕓{I1} V12. T12 ⇒ T0 & 𝕓{I1} V22. T22 ⇒ T0.
34 #I1 #V11 #V12 #T11 #T12 #V22 #T22 #IH #HV1 #HT1 #HV2 #HT2
35 elim (IH … HV1 … HV2) -HV1 HV2 // #V #HV1 #HV2
36 elim (IH … HT1 … HT2) -HT1 HT2 IH /3 width=5/
39 lemma tpr_conf_bind_zeta:
40 ∀V11,V12,T11,T12,T22,T20. (
41 ∀T1. #T1 < #V11 + #T11 +1 →
42 ∀T3,T4. T1 ⇒ T3 → T1 ⇒ T4 →
43 ∃∃T0. T3 ⇒ T0 & T4 ⇒ T0
45 V11 ⇒ V12 → T22 ⇒ T20 → T11 ⇒ T12 → ↑[O, 1] T22 ≡ T11 →
46 ∃∃T0. 𝕓{Abbr} V12. T12 ⇒ T0 & T20 ⇒ T0.
47 #V11 #V12 #T11 #T12 #T22 #T20 #IH #HV112 #HT202 #HT112 #HT
48 elim (tpr_inv_lift … HT112 … HT) -HT112 #T #HT12 #HT22
49 lapply (tw_lift … HT) -HT #HT
50 elim (IH … HT202 … HT22) -HT202 HT22 IH /3/
53 lemma tpr_conf_flat_flat:
54 ∀I1,V11,V12,T11,T12,V22,T22. (
55 ∀T1. #T1 < #V11 + #T11 + 1 →
56 ∀T3,T4. T1 ⇒ T3 → T1 ⇒ T4 →
57 ∃∃T0. T3 ⇒ T0 & T4 ⇒ T0
59 V11 ⇒ V12 → T11 ⇒ T12 →
60 V11 ⇒ V22 → T11 ⇒ T22 →
61 ∃∃T0. 𝕗{I1} V12. T12 ⇒ T0 & 𝕗{I1} V22. T22 ⇒ T0.
62 #I1 #V11 #V12 #T11 #T12 #V22 #T22 #IH #HV1 #HT1 #HV2 #HT2
63 elim (IH … HV1 … HV2) -HV1 HV2 // #V #HV1 #HV2
64 elim (IH … HT1 … HT2) -HT1 HT2 /3 width=5/
67 lemma tpr_conf_flat_beta:
68 ∀V11,V12,T12,V22,W2,T21,T22. (
69 ∀T1. #T1 < #V11 + (#W2 + #T21 + 1) + 1 →
70 ∀T3,T4. T1 ⇒ T3 → T1 ⇒ T4 →
71 ∃∃T0. T3 ⇒ T0 & T4 ⇒ T0
73 V11 ⇒ V12 → V11 ⇒ V22 →
74 T21 ⇒ T22 → 𝕓{Abst} W2. T21 ⇒ T12 →
75 ∃∃T0. 𝕗{Appl} V12. T12 ⇒ T0 & 𝕓{Abbr} V22. T22 ⇒ T0.
76 #V11 #V12 #T12 #V22 #W2 #T21 #T22 #IH #HV1 #HV2 #HT1 #HT2
77 elim (tpr_inv_abst1 … HT2) -HT2 #W1 #T1 #HW21 #HT21 #H destruct -T12;
78 elim (IH … HV1 … HV2) -HV1 HV2 // #V #HV12 #HV22
79 elim (IH … HT21 … HT1) -HT21 HT1 IH /3 width=5/
82 lemma tpr_conf_flat_theta:
83 ∀V11,V12,T12,V2,V22,W21,W22,T21,T22. (
84 ∀T1. #T1 < #V11 + (#W21 + #T21 + 1) + 1 →
85 ∀T3,T4. T1 ⇒ T3 → T1 ⇒ T4 →
86 ∃∃T0. T3 ⇒ T0 & T4 ⇒T0
88 V11 ⇒ V12 → V11 ⇒ V22 → ↑[O,1] V22 ≡ V2 →
89 W21 ⇒ W22 → T21 ⇒ T22 → 𝕓{Abbr} W21. T21 ⇒ T12 →
90 ∃∃T0. 𝕗{Appl} V12. T12 ⇒ T0 & 𝕓{Abbr} W22. 𝕗{Appl} V2. T22 ⇒T0.
93 (* Confluence ***************************************************************)
97 ∀T1. #T1 < #T → ∀T3,T4. T1 ⇒ T3 → T1 ⇒ T4 →
98 ∃∃T0. T3 ⇒ T0 & T4 ⇒ T0
100 ∀U1,T1,T2. U1 ⇒ T1 → U1 ⇒ T2 → U1 = T →
101 ∃∃T0. T1 ⇒ T0 & T2 ⇒ T0.
102 #T #IH #U1 #T1 #T2 * -U1 T1
103 [ #k1 #H1 #H2 destruct -T;
104 lapply (tpr_inv_sort1 … H1) -H1
105 (* case 1: sort, sort *)
107 | #i1 #H1 #H2 destruct -T;
108 lapply (tpr_inv_lref1 … H1) -H1
109 (* case 2: lref, lref *)
111 | #I1 #V11 #V12 #T11 #T12 #HV112 #HT112 #H1 #H2 destruct -T;
112 lapply (tpr_inv_bind1 … H1) -H1
115 theorem tpr_conf: ∀T,T1,T2. T ⇒ T1 → T ⇒ T2 →
116 ∃∃T0. T1 ⇒ T0 & T2 ⇒ T0.
117 #T @(tw_wf_ind … T) -T /3 width=6/
122 ∀T1. #T1 < #T → ∀T3,T4. T1 ⇒ T3 → T1 ⇒ T4 →
123 ∃∃T0. T3 ⇒ T0 & T4 ⇒ T0
125 ∀U1,T1,U2,T2. U1 ⇒ T1 → U2 ⇒ T2 →
127 ∃∃T0. T1 ⇒ T0 & T2 ⇒ T0.
128 #T #IH #U1 #T1 #U2 #T2
131 (* case 1: sort, sort *)
132 [ #k2 #H1 #H2 destruct -T k2 //
133 (* case 2: sort, lref (excluded) *)
134 | #i2 #H1 #H2 destruct
135 (* case 3: sort, bind (excluded) *)
136 | #I2 #V21 #V22 #T21 #T22 #_ #_ #H1 #H2 destruct
137 (* case 4: sort, flat (excluded) *)
138 | #I2 #V21 #V22 #T21 #T22 #_ #_ #H1 #H2 destruct
139 (* case 5: sort, beta (excluded) *)
140 | #V21 #V22 #W2 #T21 #T22 #_ #_ #H1 #H2 destruct
141 (* case 6: sort, delta (excluded) *)
142 | #V21 #V22 #T21 #T22 #T20 #_ #_ #_ #H1 #H2 destruct
143 (* case 7: sort, theta (excluded) *)
144 | #V2 #V21 #V22 #W21 #W22 #T21 #T22 #_ #_ #_ #_ #H1 #H2 destruct
145 (* case 8: sort, zeta (excluded) *)
146 | #V2 #T21 #T22 #T20 #_ #_ #H1 #H2 destruct
147 (* case 9: sort, tau (excluded) *)
148 | #V2 #T21 #T22 #_ #H1 #H2 destruct
151 (* case 10: lref, sort (excluded) broken *)
152 [ #k2 #H1 #H2 destruct
153 (* case 11: lref, sort (excluded) *)
154 | #i2 #H1 #H2 destruct -T i2 //
155 (* case 12: lref, bind (excluded) *)
156 | #I2 #V21 #V22 #T21 #T22 #_ #_ #H1 #H2 destruct
157 (* case 13: lref, flat (excluded) *)
158 | #I2 #V21 #V22 #T21 #T22 #_ #_ #H1 #H2 destruct
159 (* case 14: lref, beta (excluded) *)
160 | #V21 #V22 #W2 #T21 #T22 #_ #_ #H1 #H2 destruct
161 (* case 15: lref, delta (excluded) *)
162 | #V21 #V22 #T21 #T22 #T20 #_ #_ #_ #H1 #H2 destruct
163 (* case 16: lref, theta (excluded) *)
164 | #V2 #V21 #V22 #W21 #W22 #T21 #T22 #_ #_ #_ #_ #H1 #H2 destruct
165 (* case 17: lref, zeta (excluded) *)
166 | #V2 #T21 #T22 #T20 #_ #_ #H1 #H2 destruct
167 (* case 18: lref, tau (excluded) *)
168 | #V2 #T21 #T22 #_ #H1 #H2 destruct
170 | #I1 #V11 #V12 #T11 #T12 #HV112 #HT112 * -U2 T2
171 (* case 19: bind, sort (excluded) *)
172 [ #k2 #H1 #H2 destruct
173 (* case 20: bind, lref (excluded) *)
174 | #i2 #H1 #H2 destruct
175 (* case 21: bind, bind *)
176 | #I2 #V21 #V22 #T21 #T22 #HV212 #HT212 #H1 #H2
177 destruct -T I2 V21 T21 /3 width=7/
178 (* case 22: bind, flat (excluded) *)
179 | #I2 #V21 #V22 #T21 #T22 #_ #_ #H1 #H2 destruct
180 (* case 23: bind, beta (excluded) *)
181 | #V21 #V22 #W2 #T21 #T22 #_ #_ #H1 #H2 destruct
182 (* case 24: bind, delta (excluded) *)
183 | #V21 #V22 #T21 #T22 #T20 #_ #_ #_ #H1 #H2 destruct
184 (* case 25: bind, theta (excluded) *)
185 | #V2 #V21 #V22 #W21 #W22 #T21 #T22 #_ #_ #_ #_ #H1 #H2 destruct
186 (* case 26: bind, zeta *)
187 | #V2 #T21 #T22 #T20 #HT212 #HT220 #H1 #H2
188 destruct -I1 V2 T21 T /3 width=8/
189 (* case 27: bind, tau (excluded) *)
190 | #V2 #T21 #T22 #_ #H1 #H2 destruct
192 | #I1 #V11 #V12 #T11 #T12 #HV112 #HT112 * -U2 T2
193 (* case 28: flat, sort (excluded) *)
194 [ #k2 #H1 #H2 destruct
195 (* case 29: flat, lref (excluded) *)
196 | #i2 #H1 #H2 destruct
197 (* case 30: flat, bind (excluded) *)
198 | #I2 #V21 #V22 #T21 #T22 #_ #_ #H1 #H2 destruct
199 (* case 31: flat, flat *)
200 | #I2 #V21 #V22 #T21 #T22 #HV212 #HT212 #H1 #H2
201 destruct -T I2 V21 T21 /3 width=7/
202 (* case 32: flat, beta *)
203 | #V21 #V22 #W2 #T21 #T22 #HV212 #HT212 #H1 #H2
204 destruct -I1 V21 T11 T /3 width=8/ (**) (* slow *)
205 (* case 33: flat, delta (excluded) *)
206 | #V21 #V22 #T21 #T22 #T20 #_ #_ #_ #H1 #H2 destruct
207 (* case 34: flat, theta *)
208 | #V2 #V21 #V22 #W21 #W22 #T21 #T22 #H212 #HV222 #HW212 #HT212 #H1 #H2
209 destruct -I1 V21 T11 T //
211 lemma tpr_conf_flat_theta:
212 ∀V11,V12,T12,V2,V22,W21,W22,T21,T22. (
213 ∀T1. #T1 < #V11 + (#W21 + #T21 + 1) + 1 →
214 ∀T3,T4. T1 ⇒ T3 → T1 ⇒ T4 →
215 ∃∃T0. T3 ⇒ T0 & T4 ⇒T0
217 V11 ⇒ V12 → V11 ⇒ V22 → ↑[O,1] V22 ≡ V2 →
218 W21 ⇒ W22 → T21 ⇒ T22 → 𝕓{Abbr} W21. T21 ⇒ T12 →
219 ∃∃T0. 𝕗{Appl} V12. T12 ⇒ T0 & 𝕓{Abbr} W22. 𝕗{Appl} V2. T22 ⇒T0.