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3.6. Suppose that { X,) is the ARMA process defined by $(B)X, = 0(B)Z,. {Z, ) ~ WN(0, 67), where $( .) and O( .) have no common zeroes and (z) # 0 for |z| = 1. If (.) is any polynomial such that {(z) # 0for |z| = 1, show that the difference equations, (B) $(B) Y, = (B)O(B)Z,, have the unique stationary solution, { Y} = {X,}