fact: Definition hz_normal_form (i:ℤ) := coprod (∑ n, natnattohz n 0 = i) (∑ n, natnattohz 0 (S n) = i).
imports: UniMath.Foundations.NaturalNumbers UniMath.MoreFoundations.PartA UniMath.MoreFoundations.NegativePropositions UniMath.Algebra.Monoids UniMath.Algebra.Groups UniMath.Algebra.RigsAndRings UniMath.NumberSystems.NaturalNumbersAlgebra