proposition: Lemma step_edges_sp_ep : (step_edges c sp ep en) sp = ep.
proof: Proof. by rewrite step_edges_ok // eqxx. Qed.
imports: mathcomp(all_ssreflect ssralg fingroup zmodp poly ssrnum) mathcomp(matrix perm) ssr_ext ssralg_ext fdist subgraph_partition tanner