“…where ω ∈ (−π, π] and g ψ (ω) is a continuous function, bounded above and away from zero and ω ι j 0 are poles for j = 1, ..., ξ ι , ι = 1, ..., L. The autocovariance function of X t behaves like γ X (h) ∼ K j 2d ι −1 cos( jω) as h → ∞ and K is a constant that does not depend on h. See, for example, Giraitis and Leipus [17], Palma [36], Arteche [2], Arteche and Robinson [3], Reisen et al [48] and references therein. For suitable choices of the fractionally differencing parameters d ι , ι = 1, ..., L, X t may have a finite number of zeros or singularities of order d 1 ,...,d L on the unit circle which allows the modeling of long and short memory data containing seasonal periodicities.…”