proposition: Lemma mul1c : left_id C1 (@mulc R).
proof: Proof. by move=> [a b] /=; rewrite !mul1r !mul0r subr0 addr0. Qed.
imports: HB(structures) mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice fintype) mathcomp(bigop order ssralg ssrint div ssrnum rat poly closed_field) mathcomp(polyrcf matrix mxalgebra tuple mxpoly zmodp binomial realalg) mathcomp(mxpoly)