∃∃J,K. ⇩[i]L ≘ K.ⓘ[J] & ⇩*[b,⫰*[↑i]f] K ≘ K0 & ⇧*[⫰*[↑i]f] I ≘ J.
#b #f #I #L #K0 #H #i #Hf
elim (drops_split_trans … H) -H [ |5: @(pr_after_nat_uni … Hf) |2,3: skip ] /2 width=1 by pr_after_isi_dx/ #Y #HLY #H
∃∃J,K. ⇩[i]L ≘ K.ⓘ[J] & ⇩*[b,⫰*[↑i]f] K ≘ K0 & ⇧*[⫰*[↑i]f] I ≘ J.
#b #f #I #L #K0 #H #i #Hf
elim (drops_split_trans … H) -H [ |5: @(pr_after_nat_uni … Hf) |2,3: skip ] /2 width=1 by pr_after_isi_dx/ #Y #HLY #H