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# Exploring Local Norms in Exp-concave Statistical Learning

*Proceedings of Thirty Sixth Conference on Learning Theory*, PMLR 195:1993-2013, 2023.

#### Abstract

We consider the standard problem of stochastic convex optimization with exp-concave losses using Empirical Risk Minimization in a convex class. Answering a question raised in several prior works, we provide a $O ( d/n + 1/n \log( 1 / \delta ) )$ excess risk bound valid for a wide class of bounded exp-concave losses, where $d$ is the dimension of the convex reference set, $n$ is the sample size, and $\delta$ is the confidence level. Our result is based on a unified geometric assumption on the gradient of losses and the notion of local norms.