fact: Definition isdirected_lub {P : Poset} (P_DC : is_directed_complete P) {I} (p : I -> P) (p_directed : isdirected p) : least_upper_bound p.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Combinatorics.WellOrderedSets UniMath.OrderTheory.DCPOs.AlternativeDefinitions.Dcpo