proposition: Lemma hull_monotone X Y : X `<=` Y -> hull X `<=` hull Y.
proof: Proof. move=> H a [n [g [d [H0 H1]]]]; exists n, g, d; split => //. by eapply subset_trans; first exact: H0. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg fingroup perm matrix) mathcomp(mathcomp_extra boolp classical_sets Rstruct) mathcomp(ssrnum ereal) mathcomp(lra Rstruct reals) Reals ssrR Reals_ext Ranalysis_ext ssr_ext ssralg_ext logb realType_ext fdist