∀L1. G ⊢ L1 ¡⫃[h, g] L2 → ⦃G, L1⦄ ⊢ T ¡[h, g].
#h #g #G #L2 #T #H elim H -G -L2 -T //
[ #I #G #L2 #K2 #V #i #HLK2 #_ #IHV #L1 #HL12
- elim (lsubsv_ldrop_O1_trans … HL12 … HLK2) -L2 #X #H #HLK1
+ elim (lsubsv_drop_O1_trans … HL12 … HLK2) -L2 #X #H #HLK1
elim (lsubsv_inv_pair2 … H) -H * #K1
[ #HK12 #H destruct /3 width=5 by snv_lref/
| #W #l #H1V #H1W #HWV #_ #HWl #_ #_ #H1 #H2 destruct -IHV