On the minimal free resolution for fat point schemes of multiplicity at most 3 in image

Let Z be a fat point scheme in image supported on general points. Here we prove that if the multiplicities are at most 3 and the length of Z is sufficiently high then the number of generators of the homogeneous ideal IZ in each degree is as small as numerically possible. Since it is known that Z has maximal Hilbert function, this implies that Z has the expected minimal free resolution.