Exponential convergence rates in classification

  • Authors:
  • Vladimir Koltchinskii;Olexandra Beznosova

  • Affiliations:
  • Department of Mathematics and Statistics, The University of New Mexico, Albuquerque, NM;Department of Mathematics and Statistics, The University of New Mexico, Albuquerque, NM

  • Venue:
  • COLT'05 Proceedings of the 18th annual conference on Learning Theory
  • Year:
  • 2005

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Abstract

Let (X,Y) be a random couple, X being an observable instance and Y∈ {–1,1} being a binary label to be predicted based on an observation of the instance. Let (Xi, Yi), i=1, . . . , n be training data consisting of n independent copies of (X,Y). Consider a real valued classifier ${\hat{f}_{n}}$ that minimizes the following penalized empirical risk $$\frac{1}{n}\sum\limits_{i=1}^n \ell(Y_{i}f(X_{i})) + \lambda\|Let (X,Y) be a random couple, X being an observable instance and Y∈ {–1,1} being a binary label to be predicted based on an observation of the instance. Let (Xi, Yi), i=1, . . . , n be training data consisting of n independent copies of (X,Y). Consider a real valued classifier ${\hat{f}_{n}}$ that minimizes the following penalized empirical risk $$\frac{1}{n}\sum\limits_{i=1}^n \ell(Y_{i}f(X_{i})) + \lambda\|f\|^{2} \rightarrow {\rm min}, f\in {\mathcal H}$$ over a Hilbert space ${\mathcal H}$ of functions with norm || ·||, ℓ being a convex loss function and λ 0 being a regularization parameter. In particular, ${\mathcal H}$ might be a Sobolev space or a reproducing kernel Hilbert space. We provide some conditions under which the generalization error of the corresponding binary classifier sign $({\hat{f}_{n}})$ converges to the Bayes risk exponentially fast. $|^{2} \rightarrow {\rm min}, f\in {\mathcal H}$$ over a Hilbert space ${\mathcal H}$ of functions with norm || ·||, ℓ being a convex loss function and λ 0 being a regularization parameter. In particular, ${\mathcal H}$ might be a Sobolev space or a reproducing kernel Hilbert space. We provide some conditions under which the generalization error of the corresponding binary classifier sign $({\hat{f}_{n}})$ converges to the Bayes risk exponentially fast.