fact: Definition add_edge (G: graph) (x y: G) (u: Le): graph := @Graph (vertex G) (option (edge G)) (fun b e => match e with Some e => endpoint b e | None => if b then y else x end) (@vlabel _ _ G) (fun e => match e with Some e => elabel e | None => u end).
imports: Coq(Morphisms RelationClasses) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij) GraphTheory(equiv digraph setoid_bigop structures)