proposition: Lemma tree_like_rev_step : tree_like c' -> tree_like c.
proof: Proof. apply tree_like_rev_subrel. apply monotonic_step_rel. Qed.
imports: mathcomp(all_ssreflect ssralg fingroup zmodp poly ssrnum) mathcomp(matrix perm) ssr_ext ssralg_ext fdist subgraph_partition tanner