Module Import GenHigh := GenHighImpl.Impl GenLow.

Lemma semFreqSize :
forall {A : Type} (ng : nat * G A) (l : seq (nat * G A)) (size : nat),
List.Forall (fun x => x.1 > 0) (ng :: l) ->
semGenSize (freq ((fst ng, snd ng) ;; l)) size <-->
\bigcup_(x in (ng :: l)) semGenSize x.2 size.