+
+lemma csx_inv_lref_drops (h) (G):
+ ∀L,i. ❪G,L❫ ⊢ ⬈*[h] 𝐒❪#i❫ →
+ ∨∨ ⇩*[Ⓕ,𝐔❨i❩] L ≘ ⋆
+ | ∃∃I,K. ⇩[i] L ≘ K.ⓤ[I]
+ | ∃∃I,K,V. ⇩[i] L ≘ K.ⓑ[I]V & ❪G,K❫ ⊢ ⬈*[h] 𝐒❪V❫.
+#h #G #L #i #H elim (drops_F_uni L i) /2 width=1 by or3_intro0/
+* * /4 width=9 by csx_inv_lref_pair_drops, ex2_3_intro, ex1_2_intro, or3_intro2, or3_intro1/
+qed-.