(* Advanced properties ******************************************************)
lemma cpxs_delta: ∀h,g,I,G,L,K,V,V2,i.
- â\87©[i] L ≡ K.ⓑ{I}V → ⦃G, K⦄ ⊢ V ➡*[h, g] V2 →
- â\88\80W2. â\87§[0, i+1] V2 ≡ W2 → ⦃G, L⦄ ⊢ #i ➡*[h, g] W2.
+ â¬\87[i] L ≡ K.ⓑ{I}V → ⦃G, K⦄ ⊢ V ➡*[h, g] V2 →
+ â\88\80W2. â¬\86[0, i+1] V2 ≡ W2 → ⦃G, L⦄ ⊢ #i ➡*[h, g] W2.
#h #g #I #G #L #K #V #V2 #i #HLK #H elim H -V2
[ /3 width=9 by cpx_cpxs, cpx_delta/
| #V1 lapply (drop_fwd_drop2 … HLK) -HLK
lemma cpxs_inv_lref1: ∀h,g,G,L,T2,i. ⦃G, L⦄ ⊢ #i ➡*[h, g] T2 →
T2 = #i ∨
- â\88\83â\88\83I,K,V1,T1. â\87©[i] L ≡ K.ⓑ{I}V1 & ⦃G, K⦄ ⊢ V1 ➡*[h, g] T1 &
- â\87§[0, i+1] T1 ≡ T2.
+ â\88\83â\88\83I,K,V1,T1. â¬\87[i] L ≡ K.ⓑ{I}V1 & ⦃G, K⦄ ⊢ V1 ➡*[h, g] T1 &
+ â¬\86[0, i+1] T1 ≡ T2.
#h #g #G #L #T2 #i #H @(cpxs_ind … H) -T2 /2 width=1 by or_introl/
#T #T2 #_ #HT2 *
[ #H destruct