fact: Definition isassoc_plusNonnegativeRationals: ∏ x y z : NonnegativeRationals, x + y + z = x + (y + z) := CommDivRig_isassoc_plus.
imports: UniMath.MoreFoundations.Tactics UniMath.MoreFoundations.PartA UniMath.MoreFoundations.Sets UniMath.MoreFoundations.Orders UniMath.RealNumbers.Sets UniMath.RealNumbers.Fields UniMath.Algebra.DivisionRig UniMath.OrderTheory.Lattice.Lattice UniMath.RealNumbers.Prelim