Lemma ringplusminus {R: ring} (a b : R) : (a + b - b)%ring = a. Proof. rewrite ringassoc1. rewrite ringrinvax1. apply (rigrunax1 R). Defined.
Require Import UniMath.Foundations.All. Require Import UniMath.MoreFoundations.All. Require Import UniMath.Combinatorics.Maybe. Require Import UniMath.Combinatorics.StandardFiniteSets. Require Import UniMath.Algebra.Domains_and_Fields. Require Import UniMath.Algebra.RigsAndRings.