Vector valued reproducing kernel Hilbert spaces and universality
  This paper is devoted to the study of vector valued reproducing kernel Hilbert spaces. We focus on two aspects: vector valued feature maps and universal kernels. In particular we characterize the structure of translation invariant kernels on abelian groups and we relate it to the universality problem. 
C. Carmeli, E. De Vito, A. Toigo, V. Umanit\`a