fact: Definition convex_function_at_Convn f n (a : 'I_n -> T) (d : {fdist 'I_n}) := f (<|>_d a) <= <|>_d (f \o a).
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