proposition: Lemma in_vsetAV (G : pre_graph) z a x : x \in vset G -> x \in vset (G ∔ [z,a]).
proof: Proof. by rewrite !inE => ->. Qed.
imports: HB(structures) Coq(Relation_Definitions Morphisms RelationClasses) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij equiv) GraphTheory(setoid_bigop structures pttdom rewriting) GraphTheory(finmap_plus)