proposition: Lemma add_Nalg : left_inverse zero_alg opp_alg add_alg.
proof: Proof. elim/quotW=> x; rewrite !piE -equiv_alg /=. by apply: eq_crealP; exists m0=> *; rewrite /= addNr subr0 normr0. Qed.
imports: HB(structures) mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice fintype) mathcomp(bigop order ssralg ssrnum ssrint rat poly polydiv polyorder) mathcomp(perm matrix mxpoly polyXY binomial generic_quotient) mathcomp(cauchyreals separable zmodp bigenough)