proposition: Lemma ringminusdistr' { X : commring } ( a b c : X ) : (a * (b - c))%ring = (a * b - a * c)%ring.
proof: Proof. intros. rewrite ringldistr. rewrite ringrmultminus. apply idpath. Defined.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Combinatorics.Maybe UniMath.Combinatorics.StandardFiniteSets UniMath.Algebra.Domains_and_Fields UniMath.Algebra.RigsAndRings