fact: CoInductive usplit z x y : seq D -> Prop := USplit p1 p2 : upath x z p1 -> upath z y p2 -> [disjoint x::p1 & p2] -> usplit z x y (p1 ++ p2).
imports: HB(structures) Coq(Setoid CMorphisms) mathcomp(all_ssreflect) GraphTheory(edone preliminaries bij)