proposition: Lemma crossR0 : crossR 0 = 0.
proof: Proof. by rewrite /crossR /sgp_minfty /sgp_pinfty lead_coef0 mulr0 sgr0 variationr0. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice path fintype) mathcomp(div bigop order ssralg poly polydiv ssrnum perm zmodp ssrint) mathcomp(polyorder polyrcf interval matrix mxtens)