proposition: Lemma maxRE x y : max(x, y) = if (x < y)%mcR then y else x.
proof: Proof. by case: ifP => /RltP; [move/ltRW/Rmax_right|rewrite -leRNgt => /Rmax_left]. Qed.
imports: mathcomp(all_ssreflect ssralg ssrnum) Reals mathcomp(lra) mathcomp(Rstruct)