proposition: Lemma subr_onem r s : r - `1-s = r + s - 1.
proof: Proof. by rewrite /onem opprB addrA. Qed.
imports: mathcomp(all_ssreflect ssralg ssrnum) mathcomp(reals normedtype) mathcomp(mathcomp_extra boolp) mathcomp(lra ring Rstruct)