fact: Definition shell_partition : {set set_of_finType [finType of n.-tuple B]} := (fun V => V.-shell ta) @: \nu^{B}(P).
imports: mathcomp(all_ssreflect ssralg ssrnum fingroup perm) Reals mathcomp(Rstruct) ssrR Reals_ext realType_ext ssr_ext ssralg_ext logb fdist entropy num_occ channel types