proposition: Lemma connected_step_it (c : comp_graph port) t : partial_connected c -> partial_connected (step_it c t).
proof: Proof. rewrite /step_it. move: (zip _ _) => z. elim: z c => //= s b IH c Hpc. by apply IH, connected_step. Qed.
imports: mathcomp(all_ssreflect ssralg fingroup zmodp poly ssrnum) mathcomp(matrix perm) ssr_ext ssralg_ext fdist subgraph_partition tanner