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On Monte-Carlo methods in convex stochastic optimization. (English) Zbl 1502.90114

Summary: We develop a novel procedure for estimating the optimizer of general convex stochastic optimization problems of the form \(\min_{x\in \mathcal{X}}\mathbb{E}[F(x,\xi)]\), when the given data is a finite independent sample selected according to \(\xi\). The procedure is based on a median-of-means tournament, and is the first procedure that exhibits the optimal statistical performance in heavy tailed situations: we recover the asymptotic rates dictated by the central limit theorem in a nonasymptotic manner once the sample size exceeds some explicitly computable threshold. Additionally, our results apply in the high-dimensional setup, as the threshold sample size exhibits the optimal dependence on the dimension (up to a logarithmic factor). The general setting allows us to recover recent results on multivariate mean estimation and linear regression in heavy-tailed situations and to prove the first sharp, nonasymptotic results for the portfolio optimization problem.

MSC:

90C15 Stochastic programming
90C25 Convex programming
90B50 Management decision making, including multiple objectives
62J02 General nonlinear regression

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