proposition: Lemma mul2R x : 2 * x == x + x.
proof: Proof. by rewrite mulRDl !mul1R. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div order) mathcomp(ssralg ssrnum ssrint rat intdiv) Coq(Morphisms Setoid) fourcolor(real realsyntax)