[ #I #G #L #V1 #V2 #HV12 #_ elim (lift_total V2 0 1)
#U2 #HVU2 @(ex3_intro … U2)
[1,3: /3 width=7 by fqu_drop, cpxs_delta, drop_pair, drop_drop/
[ #I #G #L #V1 #V2 #HV12 #_ elim (lift_total V2 0 1)
#U2 #HVU2 @(ex3_intro … U2)
[1,3: /3 width=7 by fqu_drop, cpxs_delta, drop_pair, drop_drop/