fact: Definition Upw_underlying (T : Tree) (x : pr11 T) := ∑ (y : pr11 T), x ≤ y.
imports: UniMath.Foundations.PartB UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.Foundations.HLevels UniMath.Combinatorics.WellOrderedSets UniMath.Combinatorics.OrderedSets UniMath.MoreFoundations.DecidablePropositions UniMath.MoreFoundations.Propositions