+ @(subset_eq_trans … (unwind_fsubst …))
+ [ (*<unwind_rmap_append <unwind_rmap_A_sn <unwind_rmap_append <unwind_rmap_L_sn *)
+ <structure_append <structure_A_sn <structure_append <structure_L_sn
+ <depth_append <depth_L_sn <depth_structure <depth_structure
+ @fsubst_eq_repl [ // ]
+ @(subset_eq_trans … (unwind_iref …))
+
+ elim Hb -Hb #Hb #H0 <H0 -H0 <nrplus_zero_dx <nplus_zero_dx <nsucc_unfold
+ >Hn
+ @(subset_eq_canc_sn … (lift_term_eq_repl_dx …))
+ [ @unwind_grafted_S /2 width=2 by ex_intro/ | skip ]
+ <Hn <Hn
+(*
+ @(subset_eq_trans … (lift_term_eq_repl_dx …))
+ [ @(unwind_term_eq_repl_sn … (tls_succ_unwind q …)) | skip ]
+*)
+(*
+
+ @subset_eq_trans
+ [2: @unwind_term_eq_repl_dx
+ @(subset_eq_canc_sn … (unwind_term_eq_repl_dx …))
+
+ @(subset_eq_canc_sn … (unwind_term_eq_repl_dx …))
+ [ @unwind_grafted_S /2 width=2 by ex_intro/ | skip ]
+
+ @(subset_eq_trans … (unwind_term_after …))
+ @(subset_eq_canc_dx … (unwind_term_after …))
+ @unwind_term_eq_repl_sn -t1
+ @(stream_eq_trans … (tr_compose_uni_dx …))
+ lapply (Hn (𝐢)) -Hn >tr_id_unfold #Hn
+ lapply (pippo … b … Hn) -Hn #Hn
+ @tr_compose_eq_repl
+ [ <unwind_rmap_pap_le //
+ <Hn <nrplus_inj_sn //
+ |
+ ]
+*)