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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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15 include "basic_2/static/ssta_ssta.ma".
16 include "basic_2/computation/ygt.ma".
17 include "basic_2/equivalence/fpcs_cpcs.ma".
18 include "basic_2/dynamic/snv_ltpss_dx.ma".
20 (* STRATIFIED NATIVE VALIDITY FOR TERMS *************************************)
22 (* Inductive premises for the preservation results **************************)
24 definition IH_ssta_cprs: ∀h:sh. sd h → relation2 lenv term ≝
25 λh,g,L1,T1. ⦃h, L1⦄ ⊩ T1 :[g] →
26 ∀U1,l. ⦃h, L1⦄ ⊢ T1 •[g, l] U1 →
27 ∀L2. L1 ➡ L2 → ∀T2. L2 ⊢ T1 ➡* T2 →
28 ∃∃U2. ⦃h, L2⦄ ⊢ T2 •[g, l] U2 & ⦃L1, U1⦄ ⬌* ⦃L2, U2⦄.
30 definition IH_snv_dxprs: ∀h:sh. sd h → relation2 lenv term ≝
31 λh,g,L1,T1. ⦃h, L1⦄ ⊩ T1 :[g] →
32 ∀L2. L1 ➡ L2 → ∀T2. ⦃h, L2⦄ ⊢ T1 •*➡*[g] T2 → ⦃h, L2⦄ ⊩ T2 :[g].
34 fact ssta_cpcs_aux: ∀h,g,L,T1,T2. IH_ssta_cprs h g L T1 → IH_ssta_cprs h g L T2 →
35 ⦃h, L⦄ ⊩ T1 :[g] → ⦃h, L⦄ ⊩ T2 :[g] →
36 ∀U1,l1. ⦃h, L⦄ ⊢ T1 •[g, l1] U1 →
37 ∀U2,l2. ⦃h, L⦄ ⊢ T2 •[g, l2] U2 →
39 l1 = l2 ∧ L ⊢ U1 ⬌* U2.
40 #h #g #L #T1 #T2 #IH1 #IH2 #HT1 #HT2 #U1 #l1 #HTU1 #U2 #l2 #HTU2 #H
41 elim (cpcs_inv_cprs … H) -H #T #H1 #H2
42 elim (IH1 … HT1 … HTU1 … H1) -T1 // #W1 #H1 #HUW1
43 elim (IH2 … HT2 … HTU2 … H2) -T2 // #W2 #H2 #HUW2
44 elim (ssta_mono … H1 … H2) -T #H1 #H2 destruct
45 lapply (fpcs_canc_dx … HUW1 … HUW2) -W2 #HU12
46 lapply (fpcs_inv_cpcs … HU12) -HU12 /2 width=1/
49 definition IH_ssta_ltpr_tpr: ∀h:sh. sd h → relation2 lenv term ≝
50 λh,g,L1,T1. ⦃h, L1⦄ ⊩ T1 :[g] →
51 ∀U1,l. ⦃h, L1⦄ ⊢ T1 •[g, l] U1 →
52 ∀L2. L1 ➡ L2 → ∀T2. T1 ➡ T2 →
53 ∃∃U2. ⦃h, L2⦄ ⊢ T2 •[g, l] U2 & ⦃L1, U1⦄ ⬌* ⦃L2, U2⦄.
55 definition IH_snv_ltpr_tpr: ∀h:sh. sd h → relation2 lenv term ≝
56 λh,g,L1,T1. ⦃h, L1⦄ ⊩ T1 :[g] →
57 ∀L2. L1 ➡ L2 → ∀T2. T1 ➡ T2 → ⦃h, L2⦄ ⊩ T2 :[g].
59 definition IH_snv_ssta: ∀h:sh. sd h → relation2 lenv term ≝
60 λh,g,L1,T1. ⦃h, L1⦄ ⊩ T1 :[g] →
61 ∀U1,l. ⦃h, L1⦄ ⊢ T1 •[g, l + 1] U1 → ⦃h, L1⦄ ⊩ U1 :[g].
63 fact ssta_ltpr_cpr_aux: ∀h,g,L1,T1. IH_ssta_ltpr_tpr h g L1 T1 →
65 ∀U1,l. ⦃h, L1⦄ ⊢ T1 •[g, l] U1 →
66 ∀L2. L1 ➡ L2 → ∀T2. L2 ⊢ T1 ➡ T2 →
67 ∃∃U2. ⦃h, L2⦄ ⊢ T2 •[g, l] U2 & ⦃L1, U1⦄ ⬌* ⦃L2, U2⦄.
68 #h #g #L1 #T1 #IH #HT1 #U1 #l #HTU1 #L2 #HL12 #T2 * #T #HT1T #HTT2
69 elim (IH … HTU1 … HL12 … HT1T) // -HL12 -T1 #U #HTU #HU1
70 elim (ssta_tpss_conf … HTU … HTT2) -T #U2 #HTU2 #HU2
71 lapply (fpcs_fpr_strap1 … HU1 L2 U2 ?) -HU1 /2 width=3/ /3 width=3/
74 fact snv_ltpr_cpr_aux: ∀h,g,L1,T1. IH_snv_ltpr_tpr h g L1 T1 →
76 ∀L2. L1 ➡ L2 → ∀T2. L2 ⊢ T1 ➡ T2 → ⦃h, L2⦄ ⊩ T2 :[g].
77 #h #g #L1 #T1 #IH #HT1 #L2 #HL12 #T2 * #T #HT1T #HTT2
78 lapply (IH … HL12 … HT1T) -HL12 // -T1 #HT0
79 lapply (snv_tpss_conf … HT0 … HTT2) -T //
82 fact snv_cprs_aux: ∀h,g,L0,T0.
83 (∀L1,T1. h ⊢ ⦃L0, T0⦄ >[g] ⦃L1, T1⦄ → IH_snv_ltpr_tpr h g L1 T1) →
84 ∀L1,T1. h ⊢ ⦃L0, T0⦄ >[g] ⦃L1, T1⦄ → ⦃h, L1⦄ ⊩ T1 :[g] →
85 ∀T2. L1 ⊢ T1 ➡* T2 → ⦃h, L1⦄ ⊩ T2 :[g].
86 #h #g #L0 #T0 #IH #L1 #T1 #HLT0 #HT1 #T2 #H
87 @(cprs_ind … H) -T2 // -HT1
88 /4 width=6 by snv_ltpr_cpr_aux, ygt_cprs_trans/
91 fact ssta_cprs_aux: ∀h,g,L0,T0.
92 (∀L1,T1. h ⊢ ⦃L0, T0⦄ >[g] ⦃L1, T1⦄ → IH_snv_ltpr_tpr h g L1 T1) →
93 (∀L1,T1. h ⊢ ⦃L0, T0⦄ >[g] ⦃L1, T1⦄ → IH_ssta_ltpr_tpr h g L1 T1) →
94 ∀L1,T1. h ⊢ ⦃L0, T0⦄ >[g] ⦃L1, T1⦄ → ⦃h, L1⦄ ⊩ T1 :[g] →
95 ∀U1,l. ⦃h, L1⦄ ⊢ T1 •[g, l] U1 → ∀T2. L1 ⊢ T1 ➡* T2 →
96 ∃∃U2. ⦃h, L1⦄ ⊢ T2 •[g, l] U2 & L1 ⊢ U1 ⬌* U2.
97 #h #g #L0 #T0 #IH2 #IH1 #L1 #T1 #H01 #HT1 #U1 #l #HTU1 #T2 #H
98 @(cprs_ind … H) -T2 [ /2 width=3/ ]
99 #T #T2 #HT1T #HTT2 * #U #HTU #HU1
100 elim (ssta_ltpr_cpr_aux … HTU … HTT2) //
101 [2: /3 width=7 by snv_cprs_aux, ygt_cprs_trans/
102 |3: /3 width=3 by ygt_cprs_trans/
103 ] -L0 -T0 -T1 -T #U2 #HTU2 #HU2
104 lapply (fpcs_inv_cpcs … HU2) -HU2 #HU2
105 lapply (cpcs_trans … HU1 … HU2) -U /2 width=3/
108 fact ssta_cpcs_aux: ∀h,g,L0,T0.
109 (∀L1,T1. h ⊢ ⦃L0, T0⦄ >[g] ⦃L1, T1⦄ → IH_snv_ltpr_tpr h g L1 T1) →
110 (∀L1,T1. h ⊢ ⦃L0, T0⦄ >[g] ⦃L1, T1⦄ → IH_ssta_ltpr_tpr h g L1 T1) →
111 ∀L,T1,T2. h ⊢ ⦃L0, T0⦄ >[g] ⦃L, T1⦄ → h ⊢ ⦃L0, T0⦄ >[g] ⦃L, T2⦄ →
112 ⦃h, L⦄ ⊩ T1 :[g] → ⦃h, L⦄ ⊩ T2 :[g] →
113 ∀U1,l1. ⦃h, L⦄ ⊢ T1 •[g, l1] U1 →
114 ∀U2,l2. ⦃h, L⦄ ⊢ T2 •[g, l2] U2 →
116 l1 = l2 ∧ L ⊢ U1 ⬌* U2.
117 #h #g #L0 #T0 #IH2 #IH1 #L #T1 #T2 #HLT01 #HLT02 #HT1 #HT2 #U1 #l1 #HTU1 #U2 #l2 #HTU2 #H
118 elim (cpcs_inv_cprs … H) -H #T #H1 #H2
119 elim (ssta_cprs_aux … HLT01 HT1 … HTU1 … H1) -T1 /2 width=1/ #W1 #H1 #HUW1
120 elim (ssta_cprs_aux … HLT02 HT2 … HTU2 … H2) -T2 /2 width=1/ #W2 #H2 #HUW2 -L0 -T0
121 elim (ssta_mono … H1 … H2) -h -T #H1 #H2 destruct
122 lapply (cpcs_canc_dx … HUW1 … HUW2) -W2 /2 width=1/