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Subsampled Stochastic Variance-Reduced Gradient Langevin Dynamics
Proceedings of the 34th Conference on Uncertainty in Artificial Intelligence, PMLR R16:507-517, 2018.
Abstract
Stochastic variance-reduced gradient Langevin dynamics (SVRG-LD) was recently proposed to improve the performance of stochastic gra- dient Langevin dynamics (SGLD) by reduc- ing the variance of the stochastic gradient. In this paper, we propose a variant of SVRG-LD, namely SVRG-LD+, which replaces the full gradient in each epoch with a subsampled one. We provide a nonasymptotic analysis of the convergence of SVRG-LD+ in 2-Wasserstein distance, and show that SVRG-LD+ enjoys a lower gradient complexity1 than SVRG-LD, when the sample size is large or the target ac- curacy requirement is moderate. Our analysis directly implies a sharper convergence rate for SVRG-LD, which improves the existing con- vergence rate by a factor of $\kappa$1/6n1/6, where $\kappa$ is the condition number of the log-density function and n is the sample size. Experiments on both synthetic and real-world datasets vali- date our theoretical results.