fact: Fixpoint tree_enum l k : seq (tree l k) := match l with | O => [:: Frontier k] | l'.+1 => let en := tree_enum l' (negk k) in map (@Node _ _) (finseqs en n) end.
imports: mathcomp(all_ssreflect ssralg fingroup zmodp poly ssrnum) mathcomp(matrix perm) ssr_ext ssralg_ext fdist