proposition: Lemma ltr_distlC x y e : (`|x - y| < e) = (x - e < y < x + e).
proof: Proof. by rewrite distrC ltr_distl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)