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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 *)
10 (* \ / This file is distributed under the terms of the *)
11 (* v GNU General Public License Version 2 *)
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15 include "basic_2/grammar/tstc_tstc.ma".
16 include "basic_2/computation/cprs_cprs.ma".
17 include "basic_2/computation/csn_alt.ma".
18 include "basic_2/computation/csn_lift.ma".
20 (* CONTEXT-SENSITIVE STRONGLY NORMALIZING TERMS *****************************)
22 (* Advanced properties ******************************************************)
24 lemma csn_lpr_conf: ∀L1,L2. L1 ⊢ ➡ L2 → ∀T. L1 ⊢ ⬊* T → L2 ⊢ ⬊* T.
25 #L1 #L2 #HL12 #T #H @(csn_ind_alt … H) -T #T #_ #IHT
26 @csn_intro #T0 #HLT0 #HT0
27 @IHT /2 width=2/ -IHT -HT0 /2 width=3 by lpr_cpr_trans/
30 lemma csn_abbr: ∀a,L,V. L ⊢ ⬊* V → ∀T. L. ⓓV ⊢ ⬊* T → L ⊢ ⬊* ⓓ{a}V. T.
31 #a #L #V #HV elim HV -V #V #_ #IHV #T #HT @(csn_ind_alt … HT) -T #T #HT #IHT
33 elim (cpr_inv_abbr1 … H1) -H1 *
34 [ #V1 #T1 #HLV1 #HLT1 #H destruct
35 elim (eq_false_inv_tpair_sn … H2) -H2
36 [ #HV1 @IHV // /2 width=1/ -HV1
37 @(csn_lpr_conf (L. ⓓV)) /2 width=1/ -HLV1 /2 width=3 by csn_cpr_trans/
38 | -IHV -HLV1 * #H destruct /3 width=1/
40 | -IHV -IHT -H2 #T0 #HLT0 #HT0
41 lapply (csn_cpr_trans … HT … HLT0) -T #HLT0
42 lapply (csn_inv_lift … HLT0 … HT0) -T0 /2 width=3/
46 fact csn_appl_beta_aux: ∀a,L,W. L ⊢ ⬊* W → ∀U. L ⊢ ⬊* U →
47 ∀V,T. U = ⓓ{a}V. T → L ⊢ ⬊* ⓐV. ⓛ{a}W. T.
48 #a #L #W #H elim H -W #W #_ #IHW #X #H @(csn_ind_alt … H) -X #X #HVT #IHVT #V #T #H destruct
49 lapply (csn_fwd_pair_sn … HVT) #HV
50 lapply (csn_fwd_bind_dx … HVT) #HT -HVT
52 elim (cpr_inv_appl1 … H) -H *
53 [ #V0 #Y #HLV0 #H #H0 destruct
54 elim (cpr_fwd_abst1 … H Abbr V) -H #W0 #T0 #HLW0 #HLT0 #H destruct
55 elim (eq_false_inv_beta … H2) -H2
56 [ -IHVT #HW0 @IHW -IHW [1,5: // |3: skip ] -HLW0 /2 width=1/ -HW0
57 @csn_abbr /2 width=3 by csn_cpr_trans/ -HV
58 @(csn_lpr_conf (L.ⓓV)) /2 width=1/ -V0 /2 width=3 by csn_cpr_trans/
59 | -IHW -HLW0 -HV -HT * #H #HVT0 destruct
60 @(IHVT … HVT0) -IHVT -HVT0 // /3 width=1/
62 | -IHW -IHVT -H2 #b #V0 #W0 #T0 #T1 #HLV0 #HLT01 #H1 #H2 destruct
63 lapply (cpr_lsubr_trans … HLT01 (L.ⓓV) ?) -HLT01 /2 width=1/ #HLT01
64 @csn_abbr /2 width=3 by csn_cpr_trans/ -HV
65 @(csn_lpr_conf (L. ⓓV)) /2 width=1/ -V0 /2 width=3 by csn_cpr_trans/
66 | -IHW -IHVT -HV -HT -H2 #b #V0 #V1 #W0 #W1 #T0 #T1 #_ #_ #_ #_ #H destruct
70 (* Basic_1: was: sn3_beta *)
71 lemma csn_appl_beta: ∀a,L,W. L ⊢ ⬊* W → ∀V,T. L ⊢ ⬊* ⓓ{a}V. T →
73 /2 width=3 by csn_appl_beta_aux/ qed.
75 fact csn_appl_theta_aux: ∀a,L,U. L ⊢ ⬊* U → ∀V1,V2. ⇧[0, 1] V1 ≡ V2 →
76 ∀V,T. U = ⓓ{a}V. ⓐV2. T → L ⊢ ⬊* ⓐV1. ⓓ{a}V. T.
77 #a #L #X #H @(csn_ind_alt … H) -X #X #HVT #IHVT #V1 #V2 #HV12 #V #T #H destruct
78 lapply (csn_fwd_pair_sn … HVT) #HV
79 lapply (csn_fwd_bind_dx … HVT) -HVT #HVT
81 elim (cpr_inv_appl1 … HL) -HL *
82 [ -HV #V0 #Y #HLV10 #HL #H0 destruct
83 elim (cpr_inv_abbr1 … HL) -HL *
84 [ #V3 #T3 #HV3 #HLT3 #H0 destruct
85 elim (lift_total V0 0 1) #V4 #HV04
86 elim (term_eq_dec (ⓓ{a}V.ⓐV2.T) (ⓓ{a}V3.ⓐV4.T3))
88 elim (eq_false_inv_tpair_sn … H) -H
89 [ -HLV10 -HV3 -HLT3 -HVT
90 >(lift_inj … HV12 … HV04) -V4
95 lapply (cpr_lift … HLV10 (L. ⓓV) … HV12 … HV04) -HLV10 -HV12 /2 width=1/ #HV24
96 @(IHVT … H … HV04) -IHVT // -H -HV04 /4 width=1/
98 | -H -IHVT #T0 #HLT0 #HT0 #H0 destruct
99 lapply (csn_cpr_trans … HVT (ⓐV2.T0) ?) /2 width=1/ -T #HVT0
100 lapply (csn_inv_lift L … 1 HVT0 ? ? ?) -HVT0 [ /2 width=4/ |2,3: skip | /2 width=1/ ] -V2 -T0 #HVY
101 @(csn_cpr_trans … HVY) /2 width=1/
103 | -HV -HV12 -HVT -IHVT -H #b #V0 #W0 #T0 #T1 #_ #_ #H destruct
104 | -IHVT -H #b #V0 #V3 #W0 #W1 #T0 #T1 #HLV10 #HV03 #HLW01 #HLT01 #H1 #H2 destruct
105 lapply (cpr_lift … HLV10 (L. ⓓW0) … HV12 … HV03) -HLV10 -HV12 -HV03 /2 width=1/ #HLV23
106 @csn_abbr /2 width=3 by csn_cpr_trans/ -HV
107 @(csn_lpr_conf (L. ⓓW0)) /2 width=1/ -W1
108 @(csn_cprs_trans … HVT) -HVT /3 width=1/
112 lemma csn_appl_theta: ∀a,V1,V2. ⇧[0, 1] V1 ≡ V2 →
113 ∀L,V,T. L ⊢ ⬊* ⓓ{a}V. ⓐV2. T → L ⊢ ⬊* ⓐV1. ⓓ{a}V. T.
114 /2 width=5 by csn_appl_theta_aux/ qed.
116 (* Basic_1: was only: sn3_appl_appl *)
117 lemma csn_appl_simple_tstc: ∀L,V. L ⊢ ⬊* V → ∀T1.
119 (∀T2. L ⊢ T1 ➡* T2 → (T1 ≃ T2 → ⊥) → L ⊢ ⬊* ⓐV. T2) →
120 𝐒⦃T1⦄ → L ⊢ ⬊* ⓐV. T1.
121 #L #V #H @(csn_ind … H) -V #V #_ #IHV #T1 #H @(csn_ind … H) -T1 #T1 #H1T1 #IHT1 #H2T1 #H3T1
123 elim (cpr_inv_appl1_simple … HL ?) -HL //
124 #V0 #T0 #HLV0 #HLT10 #H0 destruct
125 elim (eq_false_inv_tpair_sn … H) -H
127 @(csn_cpr_trans … (ⓐV0.T1)) /2 width=1/ -HLT10
128 @IHV -IHV // -H1T1 -H3T1 /2 width=1/ -HV0
130 @(csn_cpr_trans … (ⓐV.T2)) /2 width=1/ -HLV0
131 @H2T1 -H2T1 // -HLT12 /2 width=1/
132 | -IHV -H1T1 -HLV0 * #H #H1T10 destruct
133 elim (tstc_dec T1 T0) #H2T10
134 [ @IHT1 -IHT1 // /2 width=1/ -H1T10 /2 width=3/ -H3T1
136 @H2T1 -H2T1 /2 width=3/ -HLT10 -HLT02 /3 width=3/
138 @H2T1 -H2T1 /2 width=1/