(* CONTEXT-SENSITIVE EXTENDED PARALLEL EVALUATION ON TERMS ******************)
definition cpxe: ∀h. sd h → relation4 genv lenv term term ≝
- λh,g,G,L,T1,T2. ⦃G, L⦄ ⊢ T1 ➡*[h, g] T2 ∧ ⦃G, L⦄ ⊢ 𝐍[h, g]⦃T2⦄.
+ λh,g,G,L,T1,T2. ⦃G, L⦄ ⊢ T1 ➡*[h, g] T2 ∧ ⦃G, L⦄ ⊢ ➡[h, g] 𝐍⦃T2⦄.
interpretation "context-sensitive extended parallel evaluation (term)"
'PEval h g G L T1 T2 = (cpxe h g G L T1 T2).
lemma csx_cpxe: ∀h,g,G,L,T1. ⦃G, L⦄ ⊢ ⬊*[h, g] T1 → ∃T2. ⦃G, L⦄ ⊢ T1 ➡*[h, g] 𝐍⦃T2⦄.
#h #g #G #L #T1 #H @(csx_ind … H) -T1
-#T1 #_ #IHT1
-elim (cnx_dec h g G L T1) /3 width=3/
-* #T #H1T1 #H2T1
-elim (IHT1 … H1T1 H2T1) -IHT1 -H2T1 #T2 * /4 width=3/
+#T1 #_ #IHT1 elim (cnx_dec h g G L T1) /3 width=3 by ex_intro, conj/
+* #T #H1T1 #H2T1 elim (IHT1 … H1T1 H2T1) -IHT1 -H2T1
+#T2 * /4 width=3 by cpxs_strap2, ex_intro, conj/
qed-.