fact: Definition retract_is_nat_to_sr : NaturalsToSemiRing SR := λ R _ _ _ _ , naturals_to_semiring N R ∘ f⁻¹.
imports: Coq.setoid_ring.Ring MathClasses.interfaces.abstract_algebra MathClasses.implementations.peano_naturals MathClasses.theory.rings Coq.Arith.PeanoNat MathClasses.categories.varieties MathClasses.theory.ua_transference MathClasses.interfaces.naturals