Polynomial to linear: efficient classification with conjunctive features

  • Authors:
  • Naoki Yoshinaga;Masaru Kitsuregawa

  • Affiliations:
  • University of Tokyo, Meguro-ku, Tokyo;University of Tokyo, Meguro-ku, Tokyo

  • Venue:
  • EMNLP '09 Proceedings of the 2009 Conference on Empirical Methods in Natural Language Processing: Volume 3 - Volume 3
  • Year:
  • 2009

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Abstract

This paper proposes a method that speeds up a classifier trained with many conjunctive features: combinations of (primitive) features. The key idea is to precompute as partial results the weights of primitive feature vectors that appear frequently in the target NLP task. A trie compactly stores the primitive feature vectors with their weights, and it enables the classifier to find for a given feature vector its longest prefix feature vector whose weight has already been computed. Experimental results for a Japanese dependency parsing task show that our method speeded up the svm and llm classifiers of the parsers, which achieved accuracy of 90.84/90.71%, by a factor of 10.7/11.6.