We address the problem of density estimation with $\bL_p$--loss by selection
of kernel estimators. We develop a selection procedure and derive
corresponiding $\bL_p$--risk oracle inequalities. It is shown that the proposed
selection rule leads to the minimax estimator that is adaptive over a scale of
the anisotropic Nikol'ski classes. The main technical tools used in our
derivations are uniform bounds on the $\bL_p$--norms of empirical processes
developed recently in Goldenshluger and Lepski~(2010).
We consider the one-armed bandit problem of Woodroofe [J. Amer. Statist.
Assoc. 74 (1979) 799--806], which involves sequential sampling from two
populations: one whose characteristics are known, and one which depends on an
unknown parameter and incorporates a covariate. The goal is to maximize
cumulative expected reward. We study this problem in a minimax setting, and
develop rate-optimal polices that involve suitable modifications of the myopic
rule.
We consider the one-armed bandit problem of Woodroofe [J. Amer. Statist.
Assoc. 74 (1979) 799--806], which involves sequential sampling from two
populations: one whose characteristics are known, and one which depends on an
unknown parameter and incorporates a covariate. The goal is to maximize
cumulative expected reward. We study this problem in a minimax setting, and
develop rate-optimal polices that involve suitable modifications of the myopic
rule.