proposition: Lemma p_of_rsC r s : [p_of r, s] = [p_of s, r].
proof: Proof. by apply/val_inj; rewrite /= !p_of_rsE mulrC. Qed.
imports: mathcomp(all_ssreflect ssralg ssrnum) mathcomp(reals normedtype) mathcomp(mathcomp_extra boolp) mathcomp(lra ring Rstruct)