fact: Definition union (F G : graph) : graph := {| vertex := (F + G)%type; edge := (edge F + edge G)%type; endpoint b := sumf (@endpoint _ _ F b) (@endpoint _ _ G b); vlabel e := match e with inl e => vlabel e | inr e => vlabel e end; elabel e := match e with inl e => elabel e | inr e => elabel e end; |}.
imports: Coq(Morphisms RelationClasses) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij) GraphTheory(equiv digraph setoid_bigop structures)