fact: Record chan_star := mkChan { c :> `Ch ; input_not_0 : (0 < #|A|)%nat }.
imports: mathcomp(all_ssreflect all_algebra) Reals mathcomp(Rstruct) ssrR Reals_ext logb ssr_ext ssralg_ext bigop_ext fdist proba entropy jfdist_cond