... functions on Sp2n(k) spanned by the integrals(2.43). Then tψ(σ) consists of ψU,1-Whittaker functions and affords a smoothrepresentation, by right translations ofSp2n(k). By construction, ... k∗(this is clear from the action by conjugation of thediagonal subgroup on U). Thus, we may replace ψ by ψα2, and hence we mayjust assume that α =1,sothat there is a nontrivial character ψ0of ... candecompose Θ(Π,ψ0)=Σiinto a direct sum of irreducible summands. Notethat each summand is (irreducible and) cuspidal. Since Θ(Π,ψ0)isgeneric,there is a summand, call it Σ, which is generic....