proposition: Lemma endpt_add_edge (G : pre_graph) e b x y u : endpt (G ∔ [e,x,u,y]) b e = if b then y else x.
proof: Proof. by rewrite /= updateE. 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)