“…The next step is to prove that the series (25), (26) and (29), which define Xs,t and Xs,t, converge absolutely. We need absolute convergence to guarantee (27) and (28). These series, however, do not necessarily converge absolutely for all s and t, but we will prove To prove that the series (25), (26) and (29) converge absolutely we need infonnation about the asymptotic behaviour of aj,~j, Cj and dj • Below we start to prove that aj and~j decrease exponentially fast, for which we need the following monotonicity result Lemma 4.…”