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Title: Projected Stochastic Gradient Langevin Algorithms for Constrained Sampling and Non-Convex Learning
Langevin algorithms are gradient descent methods with additive noise. They have been used for decades in Markov Chain Monte Carlo (MCMC) sampling, optimization, and learning. Their convergence properties for unconstrained non-convex optimization and learning problems have been studied widely in the last few years. Other work has examined projected Langevin algorithms for sampling from log-concave distributions restricted to convex compact sets. For learning and optimization, log-concave distributions correspond to convex losses. In this paper, we analyze the case of non-convex losses with compact convex constraint sets and IID external data variables. We term the resulting method the projected stochastic gradient Langevin algorithm (PSGLA). We show the algorithm achieves a deviation of 𝑂(𝑇−1/4(𝑙𝑜𝑔𝑇)1/2) from its target distribution in 1-Wasserstein distance. For optimization and learning, we show that the algorithm achieves 𝜖-suboptimal solutions, on average, provided that it is run for a time that is polynomial in 𝜖 and slightly super-exponential in the problem dimension.  more » « less
Award ID(s):
2122856
NSF-PAR ID:
10354811
Author(s) / Creator(s):
Editor(s):
Belkin, M.; Kpotufe, S.
Date Published:
Journal Name:
Proceedings of Thirty Fourth Conference on Learning Theory
Volume:
PMLR 134
Page Range / eLocation ID:
2891-2937
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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