fact: Definition directed_lub {P : Poset} (P_DC : is_directed_complete P) (p : Directed_family P) : least_upper_bound p.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Combinatorics.WellOrderedSets UniMath.OrderTheory.DCPOs.AlternativeDefinitions.Dcpo