Agnostic Boosting

  • Authors:
  • Shai Ben-David;Philip M. Long;Yishay Mansour

  • Affiliations:
  • -;-;-

  • Venue:
  • COLT '01/EuroCOLT '01 Proceedings of the 14th Annual Conference on Computational Learning Theory and and 5th European Conference on Computational Learning Theory
  • Year:
  • 2001

Quantified Score

Hi-index 0.00

Visualization

Abstract

We extend the boosting paradigm to the realistic setting of agnostic learning, that is, to a setting where the training sample is generated by an arbitrary (unknown) probability distribution over examples and labels. We define a β-weak agnostic learner with respect to a hypothesis class F as follows: given a distribution P it outputs some hypothesis h ∈ F whose error is at most erP (F) + β, where erP (F) is the minimal error of an hypothesis from F under the distribution P (note that for some distributions the bound may exceed a half). We show a boosting algorithm that using the weak agnostic learner computes a hypothesis whose error is at most max{c1(β)er(F)c2(β), Ɛ}, in time polynomial in 1/Ɛ. While this generalization guarantee is significantly weaker than the one resulting from the known PAC boosting algorithms, one should note that the assumption required for β-weak agnostic learner is much weaker. In fact, an important virtue of the notion of weak agnostic learning is that in many cases such learning is achieved by efficient algorithms.