fact: Definition sgp_minfty (p : {poly R}) := sgr ((-1) ^+ (size p).-1 * (lead_coef p)).
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice fintype) mathcomp(bigop order ssralg poly polydiv ssrnum zmodp) mathcomp(polyorder path interval ssrint)