This work studies applications and generalizations of a simple estimation
technique that provides exponential concentration under heavy-tailed
distributions, assuming only bounded low-order moments. We show that the
technique can be used for approximate minimization of smooth and strongly
convex losses, and specifically for least squares linear regression. For
instance, our $d$-dimensional estimator requires just
$\tilde{O}(d\log(1/\delta))$ random samples to obtain a constant factor
approximation to the optimal least squares loss with probability $1-\delta$,
without requiring the covariates or noise to be bounded or subgaussian. We
provide further applications to sparse linear regression and low-rank
covariance matrix estimation with similar allowances on the noise and covariate
distributions. The core technique is a generalization of the median-of-means
estimator to arbitrary metric spaces.

该论文研究了一种简单估计技术在重尾分布下提供指数集中性的应用和推广，证明该技术可用于平滑强凸损失函数的近似最小化，特别是在最小二乘线性回归、稀疏线性回归和低秩协方差矩阵估计中具有类似的特征。