proposition: Lemma is_edge_remove_edges (G : pre_graph) E e x u y : e \notin E -> is_edge G e x u y -> is_edge (G - E) e x u y.
proof: Proof. move => He. by rewrite /is_edge /= inE He. 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)