Matrix-Regularized Multiple Kernel Learning via $(r,~p)$ Norms.

This paper examines a matrix-regularized multiple kernel learning (MKL) technique based on a notion of $(r,~p)$ norms. For the problem of learning a linear combination in the support vector machine-based framework, model complexity is typically controlled using various regularization strategies on the combined kernel weights. Recent research has developed a generalized $\ell _{p}$ -norm MKL framework with tunable variable $p$ ($p\ge 1$) to support controlled intrinsic sparsity. Unfortunately, this “1-D” vector $\ell _{p}$ -norm hardly exploits potentially useful information on how the base kernels “interact.” To allow for higher order kernel-pair relationships, we extend the “1-D” vector $\ell _{p}$ -MKL to the “2-D” matrix $(r,~p)$ norms ($1\le r,~p<\infty $). We develop a new formulation and an efficient optimization strategy for $(r,~p)$ -MKL with guaranteed convergence. A theoretical analysis and experiments on seven UCI data sets shed light on the superiority of $(r,~p)$ -MKL over $\ell _{p}$ -MKL in various scenarios. [ABSTRACT FROM AUTHOR]