/2 width=5 by fqu_flat_dx, ex3_2_intro/
| #I #G #L2 #T #U #HTU #Y #HU
elim (lfdeq_fwd_dx … HU) #L1 #V1 #H destruct
- /5 width=12 by lfdeq_inv_lifts_bi, fqu_drop, drops_refl, drops_drop, ex3_2_intro/
+ /5 width=14 by lfdeq_inv_lifts_bi, fqu_drop, drops_refl, drops_drop, ex3_2_intro/
]
qed-.