proposition: Lemma oarc_remove_vertex (G : pre_graph) z e x y u : e \notin edges_at G z -> oarc G e x u y -> oarc (G \ z) e x u y.
proof: Proof. move => Iz [edge_e H]. apply: conj H. by rewrite inE Iz. 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)