proposition: Lemma mul_conjC_ge0 x : 0 <= x * x^*.
proof: Proof. by rewrite -normCK exprn_ge0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)