fact: Definition union_merge_l: merge_seq F l ⊎ G ≃ merge_seq (F ⊎ G) (map_pairs unl l) := Iso hom_union_merge_l.
imports: Coq(Morphisms RelationClasses) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij) GraphTheory(equiv digraph setoid_bigop structures)