+(* Note: apparently this was missing in basic_1 *)
+lemma lstas_inv_lift1: ∀h,G,d. d_deliftable_sn (lstas h G d).
+#h #G #d #L2 #T2 #U2 #H elim H -G -L2 -T2 -U2 -d
+[ #G #L2 #d #k #L1 #s #l #m #_ #X #H
+ >(lift_inv_sort2 … H) -X /2 width=3 by lstas_sort, lift_sort, ex2_intro/
+| #G #L2 #K2 #V2 #W2 #W #i #d #HLK2 #HVW2 #HW2 #IHVW2 #L1 #s #l #m #HL21 #X #H
+ elim (lift_inv_lref2 … H) * #Hil #H destruct [ -HVW2 | -IHVW2 ]
+ [ elim (drop_conf_lt … HL21 … HLK2) -L2 // #K1 #V1 #HLK1 #HK21 #HV12
+ elim (IHVW2 … HK21 … HV12) -K2 -V2 #W1 #HW12 #HVW1
+ elim (lift_trans_le … HW12 … HW2) -W2 // <yminus_succ2 <yplus_inj >yplus_SO2 >ymax_pre_sn /3 width=8 by lstas_ldef, ylt_fwd_le_succ1, ex2_intro/
+ | lapply (drop_conf_ge … HL21 … HLK2 ?) -L2 // #HL1K2
+ elim (yle_inv_plus_inj2 … Hil) -Hil #Hlim #mi
+ elim (lift_split … HW2 l (i-m+1)) -HW2 /2 width=1 by yle_succ_dx, le_S_S/
+ #W0 #HW20 <le_plus_minus_comm /2 width=1 by yle_inv_inj/ >minus_minus_m_m /3 width=8 by lstas_ldef, yle_inv_inj, le_S, ex2_intro/
+ ]
+| #G #L2 #K2 #W2 #V2 #i #HLK2 #HWV2 #IHWV2 #L1 #s #l #m #HL21 #X #H
+ elim (lift_inv_lref2 … H) * #Hil #H destruct [ -HWV2 | -IHWV2 ]
+ [ elim (drop_conf_lt … HL21 … HLK2) -L2 // #K1 #W1 #HLK1 #HK21 #HW12
+ elim (IHWV2 … HK21 … HW12) -K2
+ /3 width=5 by lstas_zero, lift_lref_lt, ex2_intro/
+ | lapply (drop_conf_ge … HL21 … HLK2 ?) -L2
+ /3 width=5 by lstas_zero, lift_lref_ge_minus, ex2_intro/
+ ]
+| #G #L2 #K2 #W2 #V2 #W #i #d #HLK2 #HWV2 #HW2 #IHWV2 #L1 #s #l #m #HL21 #X #H
+ elim (lift_inv_lref2 … H) * #Hil #H destruct [ -HWV2 | -IHWV2 ]
+ [ elim (drop_conf_lt … HL21 … HLK2) -L2 // #K1 #W1 #HLK1 #HK21 #HW12
+ elim (IHWV2 … HK21 … HW12) -K2 #V1 #HV12 #HWV1
+ elim (lift_trans_le … HV12 … HW2) -W2 // <yminus_succ2 <yplus_inj >yplus_SO2 >ymax_pre_sn /3 width=8 by lstas_succ, ylt_fwd_le_succ1, ex2_intro/
+ | lapply (drop_conf_ge … HL21 … HLK2 ?) -L2 // #HL1K2
+ elim (yle_inv_plus_inj2 … Hil) -Hil #Hlim #mi
+ elim (lift_split … HW2 l (i-m+1)) -HW2 /2 width=1 by yle_succ_dx, le_S_S/
+ #W0 #HW20 <le_plus_minus_comm /2 width=1 by yle_inv_inj/ >minus_minus_m_m /3 width=8 by lstas_succ, yle_inv_inj, le_S, ex2_intro/
+ ]
+| #a #I #G #L2 #V2 #T2 #U2 #d #_ #IHTU2 #L1 #s #l #m #HL21 #X #H
+ elim (lift_inv_bind2 … H) -H #V1 #T1 #HV12 #HT12 #H destruct
+ elim (IHTU2 (L1.ⓑ{I}V1) … HT12) -IHTU2 -HT12 /3 width=5 by lstas_bind, drop_skip, lift_bind, ex2_intro/
+| #G #L2 #V2 #T2 #U2 #d #_ #IHTU2 #L1 #s #l #m #HL21 #X #H
+ elim (lift_inv_flat2 … H) -H #V1 #T1 #HV12 #HT12 #H destruct
+ elim (IHTU2 … HL21 … HT12) -L2 -HT12 /3 width=5 by lstas_appl, lift_flat, ex2_intro/
+| #G #L2 #W2 #T2 #U2 #d #_ #IHTU2 #L1 #s #l #m #HL21 #X #H
+ elim (lift_inv_flat2 … H) -H #W1 #T1 #_ #HT12 #H destruct
+ elim (IHTU2 … HL21 … HT12) -L2 -HT12 /3 width=3 by lstas_cast, ex2_intro/
+]
+qed-.