proposition: Lemma FnextE m0 n0 : (m0 \in 'F n0) = (n0 \in 'V m0).
proof: Proof. by rewrite /Fnext; unlock; rewrite inE. Qed.
imports: mathcomp(all_ssreflect ssralg fingroup finalg perm zmodp) mathcomp(matrix) bigop_ext ssralg_ext f2 subgraph_partition