elim (IH … HT12) -IH -HT12 #L2 #T #HL12 #HT1 #H destruct
lapply (lpqs_trans … HL12 (L.ⓑ{I}V2@@L2) ?) -HL12 /3 width=1/ #HL12
@(ex3_2_intro … (⋆.ⓑ{I}V2@@L2)) [4: /2 width=3/ | skip ] <append_assoc // (**) (* explicit constructor *)
- | #T #_ #_ #H destruct
+ | #T #_ #_ #H destruct
]
]
qed-.