proposition: Lemma Sba_j_pos x: 0 < x < 1 -> 0 < (Sba_j x).
proof: Proof. by move => /andP[h1 h2]; rewrite /Sba_j invr_gt0 subr_gt0 invf_gt1. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq choice fintype order bigop ssralg) mathcomp(div ssrnum ssrint rat prime path binomial) mathcomp(tuple finset) gaia(fibm)