proposition: Lemma dest_ports_0 c : dest_ports c 0 = [set [tuple]].
proof: Proof. apply/setP => t. by rewrite !inE tuple0 eqxx set_nil set0U part_p. Qed.
imports: mathcomp(all_ssreflect ssralg fingroup zmodp poly ssrnum) mathcomp(matrix perm) ssr_ext ssralg_ext fdist subgraph_partition tanner