(* Basic properties *********************************************************)
(* Basic_1: was: tweight_lt *)
-lemma tw_pos: ∀T. 1 ≤ ♯{T}.
+lemma tw_pos: ∀T. 1 ≤ ♯❨T❩.
#T elim T -T //
qed.
+lemma tw_le_pair_dx (I): ∀V,T. ♯❨T❩ < ♯❨②[I]V.T❩.
+#I #V #T /2 width=1 by le_S_S/
+qed.
+
(* Basic_1: removed theorems 11:
wadd_le wadd_lt wadd_O weight_le weight_eq weight_add_O
weight_add_S tlt_trans tlt_head_sx tlt_head_dx tlt_wf_ind