proposition: Lemma incident_addv (G : pre_graph) x a : incident (G ∔ [x,a]) =2 incident G.
proof: Proof. done. 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)