论文标题

在随机子空间上的正规化ERM

Regularized ERM on random subspaces

论文作者

Della Vecchia, Andrea, De Vito, Ernesto, Rosasco, Lorenzo

论文摘要

我们研究了经典的经验风险最小化的自然扩展,其中假设空间是给定空间的随机子空间。特别是,我们考虑可能由数据的随机子集跨越数据依赖的子集,并作为特殊情况nystrom方法恢复了内核方法​​。考虑随机子空间自然会导致计算节省,但问题是是否降低了相应的学习精度。最近已经探索了这些统计计算的权衡方案,即最小二乘损失和自我符合损失功能,例如逻辑损失。在这里,我们致力于将这些结果扩展到凸Lipschitz损失功能,这可能不是平稳的,例如支持向量机中使用的铰链损耗。这种统一的分析需要开发新的证据,这些新证明使用不同的技术工具,例如高斯式投入,以实现快速率。我们的主要结果表明存在不同的设置,具体取决于学习问题的困难,可以提高计算效率而不会损失绩效。

We study a natural extension of classical empirical risk minimization, where the hypothesis space is a random subspace of a given space. In particular, we consider possibly data dependent subspaces spanned by a random subset of the data, recovering as a special case Nystrom approaches for kernel methods. Considering random subspaces naturally leads to computational savings, but the question is whether the corresponding learning accuracy is degraded. These statistical-computational tradeoffs have been recently explored for the least squares loss and self-concordant loss functions, such as the logistic loss. Here, we work to extend these results to convex Lipschitz loss functions, that might not be smooth, such as the hinge loss used in support vector machines. This unified analysis requires developing new proofs, that use different technical tools, such as sub-gaussian inputs, to achieve fast rates. Our main results show the existence of different settings, depending on how hard the learning problem is, for which computational efficiency can be improved with no loss in performance.

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