Clustering Induced Kernel Learning
Proceedings of The 10th Asian Conference on Machine Learning, PMLR 95:129-144, 2018.
Learning rich and expressive kernel functions is a challenging task in kernel-based supervised learning. Multiple kernel learning (MKL) approach addresses this problem by combining a mixed variety of kernels and letting the optimization solver choose the most appropriate combination. However, most of existing methods are parametric in the sense that they require a predefined list of kernels. Hence, there appears a substantial trade-off between computation and the modeling risk of not being able to explore more expressive and suitable kernel functions. Moreover, current existing approaches to combine kernels cannot exploit clustering structure carried in data, especially when data are heterogeneous. In this work, we present a new framework that leverages Bayesian nonparametric models (i.e, automatically grow kernel functions) with multiple kernel learning to develop a new framework that enjoys the nonparametric flavor in the context of multiple kernel learning. In particular, we propose Clustering Induced Kernel Learning (CIK) method that can automatically discover clustering structure from the data and train a single kernel machine to fit data in each discovered cluster simultaneously. The outcome of our proposed method includes both clustering analysis and multiple kernel classifier for a given dataset. We conduct extensive experiments on several benchmark datasets. The experimental results show that our method can improve classification and clustering performance when datasets have complex clustering structure with different preferred kernels.