fact: Definition pmf : {ffun 'I_3 -> R} := [ffun i => [fun x => 0 with inord 0 |-> 1/2, inord 1 |-> 1/3, inord 2 |-> 1/6] i].
imports: mathcomp(all_ssreflect ssrnum) Reals Lra mathcomp(Rstruct) ssrR Reals_ext fdist proba