proposition: Lemma remove_edges_edges (G : pre_graph) E E' : G - E - E' ≡G G - (E `|` E').
proof: Proof. split => //=. by rewrite fsetDDl. 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)