proposition: Lemma mulN1R x : - 1 * x == - x.
proof: Proof. by rewrite mulNR mul1R. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div order) mathcomp(ssralg ssrnum ssrint rat intdiv) Coq(Morphisms Setoid) fourcolor(real realsyntax)