L1 = K1. ⓑ{I} V1.
/2 width=3/ qed-.
-(* Basic_1: removed theorems 27:
+(* Basic_1: removed theorems 28:
csubst0_clear_O csubst0_drop_lt csubst0_drop_gt csubst0_drop_eq
csubst0_clear_O_back csubst0_clear_S csubst0_clear_trans
csubst0_drop_gt_back csubst0_drop_eq_back csubst0_drop_lt_back
csubst0_snd_bind csubst0_fst_bind csubst0_both_bind
csubst1_head csubst1_flat csubst1_gen_head
csubst1_getl_ge csubst1_getl_lt csubst1_getl_ge_back getl_csubst1
-
+ fsubst0_gen_base
*)