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4 (* ||A|| A project by Andrea Asperti *)
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15 include "basic_2/reducibility/xpr.ma".
17 include "basic_2/reducibility/cnf.ma".
19 (* EXTENDED PARALLEL COMPUTATION ON TERMS ***********************************)
21 definition xprs: ∀h. sd h → lenv → relation term ≝
22 λh,g,L. TC … (xpr h g L).
24 interpretation "extended parallel computation (term)"
25 'XPRedStar h g L T1 T2 = (xprs h g L T1 T2).
27 (* Basic eliminators ********************************************************)
29 lemma xprs_ind: ∀h,g,L,T1. ∀R:predicate term. R T1 →
30 (∀T,T2. ⦃h, L⦄ ⊢ T1 ➸*[g] T → ⦃h, L⦄ ⊢ T ➸[g] T2 → R T → R T2) →
31 ∀T2. ⦃h, L⦄ ⊢ T1 ➸*[g] T2 → R T2.
32 #h #g #L #T1 #R #HT1 #IHT1 #T2 #HT12
33 @(TC_star_ind … HT1 IHT1 … HT12) //
36 lemma xprs_ind_dx: ∀h,g,L,T2. ∀R:predicate term. R T2 →
37 (∀T1,T. ⦃h, L⦄ ⊢ T1 ➸[g] T → ⦃h, L⦄ ⊢ T ➸*[g] T2 → R T → R T1) →
38 ∀T1. ⦃h, L⦄ ⊢ T1 ➸*[g] T2 → R T1.
39 #h #g #L #T2 #R #HT2 #IHT2 #T1 #HT12
40 @(TC_star_ind_dx … HT2 IHT2 … HT12) //
43 (* Basic properties *********************************************************)
45 lemma xprs_refl: ∀h,g,L,T. ⦃h, L⦄ ⊢ T ➸*[g] T.
48 lemma xprs_strap1: ∀h,g,L,T1,T,T2.
49 ⦃h, L⦄ ⊢ T1 ➸*[g] T → ⦃h, L⦄ ⊢ T ➸[g] T2 → ⦃h, L⦄ ⊢ T1 ➸*[g] T2.
50 /2 width=3 by step/ qed. (**) (* NTypeChecker failure without trace *)
52 lemma xprs_strap2: ∀h,g,L,T1,T,T2.
53 ⦃h, L⦄ ⊢ T1 ➸[g] T → ⦃h, L⦄ ⊢ T ➸*[g] T2 → ⦃h, L⦄ ⊢ T1 ➸*[g] T2.
54 /2 width=3 by TC_strap/ qed. (**) (* NTypeChecker failure without trace *)
56 (* Basic inversion lemmas ***************************************************)
58 axiom xprs_inv_cnf1: ∀L,T,U. L ⊢ T ➡* U → L ⊢ 𝐍⦃T⦄ → T = U.
59 #L #T #U #H @(xprs_ind_dx … H) -T //
60 #T0 #T #H1T0 #_ #IHT #H2T0
61 lapply (H2T0 … H1T0) -H1T0 #H destruct /2 width=1/