A Real generalization of discrete AdaBoost

  • Authors:
  • Richard Nock;Frank Nielsen

  • Affiliations:
  • Université Antilles-Guyane, Département Scientifique Interfacultaire, Campus de Schoelcher, B.P. 7209, 97275 Schoelcher, Martinique, France. E-mail: rnock@martinique.univ-ag.fr;Sony Computer Science Laboratories Inc., 3-14-13 Higashi Gotanda, Shinagawa-Ku, Tokyo 141-0022, Japan. E-mail: Frank.Nielsen@csl.sony.co.jp

  • Venue:
  • Proceedings of the 2006 conference on ECAI 2006: 17th European Conference on Artificial Intelligence August 29 -- September 1, 2006, Riva del Garda, Italy
  • Year:
  • 2006

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Abstract

Scaling discrete AdaBoost to handle real-valued weak hypotheses has often been done under the auspices of convex optimization, but little is generally known from the original boosting model standpoint. We introduce a novel generalization of discrete AdaBoost which departs from this mainstream of algorithms. From the theoretical standpoint, it formally displays the original boosting property; furthermore, it brings interesting computational and numerical improvements that make it significantly easier to handle “as is”. Conceptually speaking, it provides a new and appealing scaling to R of some well known facts about discrete (ada)boosting. Perhaps the most popular is an iterative weight modification mechanism, according to which examples have their weights decreased iff they receive the right class by the current discrete weak hypothesis. Our generalization to real values makes that decreasing weights affect only the examples on which the hypothesis' margin exceeds its average margin. Thus, while both properties coincide on the discrete case, examples that receive the right class can still be reweighted higher with real-valued weak hypotheses. From the experimental standpoint, our generalization displays the ability to produce low error formulas with particular cumulative margin distributions, and it provides a nice handling of those noisy domains that represent Achilles' heel for common Adaptive Boosting algorithms.