Abstract: Metric and kernel learning arise in several machine learning applications. However, most existing
metric learning algorithms are limited to learning metrics over low-dimensional data, while existing
kernel learning algorithms are often limited to the transductive setting and do not generalize to new
data points. In this paper, we study the connections between metric learning and kernel learning that
arise when studying metric learning as a linear transformation learning problem. In particular, we
propose a general optimization framework for learning metrics via linear transformations, and analyze
in detail a special case of our framework—that of minimizing the LogDet divergence subject
to linear constraints. We then propose a general regularized framework for learning a kernel matrix,
and show it to be equivalent to our metric learning framework. Our theoretical connections between
metric and kernel learning have two main consequences: 1) the learned kernel matrix parameterizes
a linear transformation kernel function and can be applied inductively to new data points, 2) our
result yields a constructive method for kernelizing most existing Mahalanobis metric learning formulations.
We demonstrate our learning approach by applying it to large-scale real world problems
in computer vision, text mining and semi-supervised kernel dimensionality reduction.
Download: pdf
Citation
- Metric and Kernel Learning using a Linear Transformation (pdf, software)
P. Jain, B. Kulis, J. Davis, I. Dhillon.
Journal of Machine Learning Research (JMLR) 13, pp. 519-547, March 2012.
Bibtex: