/3 width=5 by fpb_fqu, ex3_2_intro/
| #U #HTU #HnTU elim (lfdeq_cpx_trans … HT … HTU) -HTU
/5 width=10 by fpb_cpx, cpx_lfdeq_conf_sn, tdeq_trans, tdeq_lfdeq_conf, ex3_2_intro/
/3 width=5 by fpb_fqu, ex3_2_intro/
| #U #HTU #HnTU elim (lfdeq_cpx_trans … HT … HTU) -HTU
/5 width=10 by fpb_cpx, cpx_lfdeq_conf_sn, tdeq_trans, tdeq_lfdeq_conf, ex3_2_intro/