∀V2. ⇧[0, i + 1] V1 ≡ V2 →
∀Vs. ⦃G, L⦄ ⊢ ⬊*[h, g] (ⒶVs.V2) → ⦃G, L⦄ ⊢ ⬊*[h, g] (ⒶVs.#i).
#h #g #I #G #L #K #V1 #i #HLK #V2 #HV12 #Vs elim Vs -Vs
-[ /4 width=12 by csx_inv_lift, csx_lref_bind, ldrop_fwd_drop2/
+[ /4 width=12 by csx_inv_lift, csx_lref_bind, drop_fwd_drop2/
| #V #Vs #IHV #H1T
lapply (csx_fwd_pair_sn … H1T) #HV
lapply (csx_fwd_flat_dx … H1T) #H2T