fact: Definition pr_leq (X : {RV P -> T}) r := Pr P [set x | (X x <= r)%O ].
imports: mathcomp(all_ssreflect ssralg ssrnum matrix) mathcomp(Rstruct reals) Reals Lra ssrR Reals_ext realType_ext logb ssr_ext ssralg_ext bigop_ext fdist