fact: Definition is_least_upper_bound_in_subposet {P : Poset} {A : Subposet P} {I} {p : I -> A} {x : A} (x_lub : is_least_upper_bound (subposet_incl ∘ p) (subposet_incl x)) : is_least_upper_bound p x.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Combinatorics.WellOrderedSets UniMath.OrderTheory.DCPOs.AlternativeDefinitions.Dcpo