proposition: Lemma split_dist_add (z x y e : F) : `|x - z| < e / 2%:R -> `|z - y| < e / 2%:R -> `|x - y| < e.
proof: Proof. by move=> *; rewrite (le_lt_trans (ler_dist_add z _ _)) ?splitD // 1?distrC. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice fintype) mathcomp(bigop order ssralg ssrnum ssrint rat poly polydiv polyorder) mathcomp(perm matrix mxpoly polyXY binomial bigenough)