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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/rt_equivalence/cpcs_cprs.ma".
16 include "basic_2/dynamic/cnv_preserve.ma".
17 include "basic_2/dynamic/nta.ma".
19 (* NATIVE TYPE ASSIGNMENT FOR TERMS *****************************************)
21 (* Properties based on preservation *****************************************)
23 lemma cnv_cpms_nta (a) (h) (G) (L):
24 ∀T. ⦃G,L⦄ ⊢ T ![a,h] → ∀U.⦃G,L⦄ ⊢ T ➡*[1,h] U → ⦃G,L⦄ ⊢ T :[a,h] U.
25 /3 width=4 by cnv_cast, cnv_cpms_trans/ qed.
27 lemma cnv_nta_sn (a) (h) (G) (L):
28 ∀T. ⦃G,L⦄ ⊢ T ![a,h] → ∃U. ⦃G,L⦄ ⊢ T :[a,h] U.
30 elim (cnv_fwd_cpm_SO … HT) #U #HTU
31 /4 width=2 by cnv_cpms_nta, cpm_cpms, ex_intro/
34 lemma nta_pure_cnv (h) (G) (L):
35 ∀T,U. ⦃G,L⦄ ⊢ T :*[h] U →
36 ∀V. ⦃G,L⦄ ⊢ ⓐV.U !*[h] → ⦃G,L⦄ ⊢ ⓐV.T :*[h] ⓐV.U.
37 #h #G #L #T #U #H1 #V #H2
38 elim (cnv_inv_cast … H1) -H1 #X0 #HU #HT #HUX0 #HTX0
39 elim (cnv_inv_appl … H2) #n #p #X1 #X2 #_ #HV #_ #HVX1 #HUX2
40 elim (cnv_cpms_conf … HU … HUX0 … HUX2) -HU -HUX2
41 <minus_O_n <minus_n_O #X #HX0 #H
42 elim (cpms_inv_abst_sn … H) -H #X3 #X4 #HX13 #HX24 #H destruct
43 @(cnv_cast … (ⓐV.X0)) [2:|*: /2 width=1 by cpms_appl_dx/ ]
44 @(cnv_appl … X3) [4: |*: /2 width=7 by cpms_trans, cpms_cprs_trans/ ]
48 (* Inversion lemmas based on preservation ***********************************)
50 lemma nta_inv_bind_sn_cnv (a) (h) (p) (I) (G) (K) (X2):
51 ∀V,T. ⦃G,K⦄ ⊢ ⓑ{p,I}V.T :[a,h] X2 →
52 ∃∃U. ⦃G,K⦄ ⊢ V ![a,h] & ⦃G,K.ⓑ{I}V⦄ ⊢ T :[a,h] U & ⦃G,K⦄ ⊢ ⓑ{p,I}V.U ⬌*[h] X2 & ⦃G,K⦄ ⊢ X2 ![a,h].
53 #a #h #p * #G #K #X2 #V #T #H
54 elim (cnv_inv_cast … H) -H #X1 #HX2 #H1 #HX21 #H2
55 elim (cnv_inv_bind … H1) -H1 #HV #HT
56 [ elim (cpms_inv_abbr_sn_dx … H2) -H2 *
57 [ #V0 #U #HV0 #HTU #H destruct
58 /4 width=5 by cnv_cpms_nta, cprs_div, cpms_bind, ex4_intro/
59 | #U #HTU #HX1U #H destruct
60 /4 width=5 by cnv_cpms_nta, cprs_div, cpms_zeta, ex4_intro/
62 | elim (cpms_inv_abst_sn … H2) -H2 #V0 #U #HV0 #HTU #H destruct
63 /4 width=5 by cnv_cpms_nta, cprs_div, cpms_bind, ex4_intro/
67 (* Basic_1: uses: ty3_gen_appl *)
68 lemma nta_inv_appl_sn (h) (G) (L) (X2):
69 ∀V,T. ⦃G,L⦄ ⊢ ⓐV.T :[h] X2 →
70 ∃∃p,W,U. ⦃G,L⦄ ⊢ V :[h] W & ⦃G,L⦄ ⊢ T :[h] ⓛ{p}W.U & ⦃G,L⦄ ⊢ ⓐV.ⓛ{p}W.U ⬌*[h] X2 & ⦃G,L⦄ ⊢ X2 ![h].
72 elim (cnv_inv_cast … H) -H #X #HX2 #H1 #HX2 #H2
73 elim (cnv_inv_appl … H1) * [ | #n ] #p #W #U #Hn #HV #HT #HVW #HTU
74 [ lapply (cnv_cpms_trans … HT … HTU) #H
75 elim (cnv_inv_bind … H) -H #_ #HU
76 elim (cnv_fwd_cpm_SO … HU) #U0 #HU0 -HU
77 lapply (cpms_step_dx … HTU 1 (ⓛ{p}W.U0) ?) -HTU [ /2 width=1 by cpm_bind/ ] #HTU
78 | lapply (le_n_O_to_eq n ?) [ /3 width=1 by le_S_S_to_le/ ] -Hn #H destruct
80 lapply (cpms_appl_dx … V V … HTU) [1,3: // ] #HVTU
81 elim (cnv_cpms_conf … H1 … H2 … HVTU) -H1 -H2 -HVTU <minus_n_n #X0 #HX0 #HUX0
82 @ex4_3_intro [6,13: |*: /2 width=5 by cnv_cpms_nta/ ]
83 /3 width=5 by cprs_div, cprs_trans/
86 (* Basic_2A1: uses: nta_inv_cast1 *)
87 lemma nta_inv_cast_sn (a) (h) (G) (L) (X2):
88 ∀U,T. ⦃G,L⦄ ⊢ ⓝU.T :[a,h] X2 →
89 ∧∧ ⦃G,L⦄ ⊢ T :[a,h] U & ⦃G,L⦄ ⊢ U ⬌*[h] X2 & ⦃G,L⦄ ⊢ X2 ![a,h].
90 #a #h #G #L #X2 #U #T #H
91 elim (cnv_inv_cast … H) -H #X0 #HX2 #H1 #HX20 #H2
92 elim (cnv_inv_cast … H1) #X #HU #HT #HUX #HTX
93 elim (cpms_inv_cast1 … H2) -H2 [ * || * ]
94 [ #U0 #T0 #HU0 #HT0 #H destruct -HU -HU0
95 elim (cnv_cpms_conf … HT … HTX … HT0) -HT -HTX -HT0
96 <minus_n_n #T1 #HXT1 #HT01
97 @and3_intro // @(cprs_div … T1) /3 width=4 by cprs_trans, cpms_eps/ (**) (* full auto too slow *)
99 elim (cnv_cpms_conf … HT … HTX … HTX0) -HT -HTX -HTX0
100 <minus_n_n #T1 #HXT1 #HXT01
101 @and3_intro // @(cprs_div … T1) /2 width=3 by cprs_trans/ (**) (* full auto too slow *)
102 | #m #HUX0 #H destruct -HT -HTX
103 elim (cnv_cpms_conf … HU … HUX … HUX0) -HU -HUX0
104 <minus_n_n #U1 #HXU1 #HXU01
105 @and3_intro // @(cprs_div … U1) /2 width=3 by cprs_trans/ (**) (* full auto too slow *)
109 (* Forward lemmas based on preservation *************************************)
111 (* Basic_1: was: ty3_unique *)
112 theorem nta_mono (a) (h) (G) (L) (T):
113 ∀U1. ⦃G,L⦄ ⊢ T :[a,h] U1 → ∀U2. ⦃G,L⦄ ⊢ T :[a,h] U2 → ⦃G,L⦄ ⊢ U1 ⬌*[h] U2.
114 #a #h #G #L #T #U1 #H1 #U2 #H2
115 elim (cnv_inv_cast … H1) -H1 #X1 #_ #_ #HUX1 #HTX1
116 elim (cnv_inv_cast … H2) -H2 #X2 #_ #HT #HUX2 #HTX2
117 elim (cnv_cpms_conf … HT … HTX1 … HTX2) -T <minus_n_n #X #HX1 #HX2
118 /3 width=5 by cprs_div, cprs_trans/