proposition: Lemma hr_abs_minus : ∏ x y : hr_ConstructiveField, hr_abs x - hr_abs y <= hr_abs (x - y)%ring.
proof: Proof. intros x y. rewrite <- (hr_abs_opp y). apply istriangle_hr_abs'. Qed.
imports: UniMath.Algebra.Groups UniMath.Foundations.Preamble UniMath.MoreFoundations.Orders UniMath.MoreFoundations.Tactics UniMath.OrderTheory.Lattice.Lattice UniMath.RealNumbers.Prelim UniMath.RealNumbers.Sets UniMath.RealNumbers.NonnegativeRationals UniMath.RealNumbers.NonnegativeReals