When Is There a Representer Theorem? Vector Versus Matrix Regularizers
Charles A. Micchelli and Massimiliano Pontil and Andreas Argyriou

@article{10:87,author={Andreas Argyriou and Charles A. Micchelli and Massimiliano Pontil}, Title={When Is There a Representer Theorem?  Vector Versus Matrix Regularizers},journal={Journal of Machine Learning Research},volume={10}, url={http://www.jmlr.org/papers/volume10/argyriou09a/argyriou09a.pdf}}