Direct density-ratio estimation with dimensionality reduction via least-squares hetero-distributional subspace search

  • Authors:
  • Masashi Sugiyama;Makoto Yamada;Paul von Bünau;Taiji Suzuki;Takafumi Kanamori;Motoaki Kawanabe

  • Affiliations:
  • Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan and PRESTO, Japan Science and Technology Agency, Japan;Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan;Technical University of Berlin Franklinstr. 28/29, 10587 Berlin, Germany;The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan;Nagoya University, Furocho, Chikusaku, Nagoya 464-8603, Japan;Fraunhofer FIRST.IDA, Kekuléstr. 7, 12489 Berlin, Germany

  • Venue:
  • Neural Networks
  • Year:
  • 2011

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Abstract

Methods for directly estimating the ratio of two probability density functions have been actively explored recently since they can be used for various data processing tasks such as non-stationarity adaptation, outlier detection, and feature selection. In this paper, we develop a new method which incorporates dimensionality reduction into a direct density-ratio estimation procedure. Our key idea is to find a low-dimensional subspace in which densities are significantly different and perform density-ratio estimation only in this subspace. The proposed method, D^3-LHSS (Direct Density-ratio estimation with Dimensionality reduction via Least-squares Hetero-distributional Subspace Search), is shown to overcome the limitation of baseline methods.