“…For a £ K and h £ {0, 1,2} we will sometimes write ah instead of a (a). With this convention it suffices to solve (5) )ff = x-yI3 = ±/07r'1|^2öQl^2, where n0 £ {0, 1} and h £ {0, 1,2}, and where the variables are x, y e nx,n2£ Z>0 , and ax, a2 £ Z.…”