Poster
in
Workshop: Optimal Transport and Machine Learning
Improved Stein Variational Gradient Descent with Importance Weights
Lukang Sun · Peter Richtarik
Abstract:
Stein Variational Gradient Descent~(\algname{SVGD}) is a popular sampling algorithm used in various machine learning tasks. It is well known that \algname{SVGD} arises from a discretization of the kernelized gradient flow of the Kullback-Leibler divergence \KL(⋅∣π)\KL(⋅∣π), where π is the target distribution. In this work, we propose to enhance \algname{SVGD} via the introduction of {\em importance weights}, which leads to a new method for which we coin the name \algname{β-SVGD}. In the continuous time and infinite particles regime, the time for this flow to converge to the equilibrium distribution π, quantified by the Stein Fisher information, depends on ρ0 and π very weakly. This is very different from the kernelized gradient flow of Kullback-Leibler divergence, whose time complexity depends on \KL(ρ0∣π). Under certain assumptions, we provide a descent lemma for the population limit \algname{β-SVGD}, which covers the descent lemma for the population limit \algname{SVGD} when β→0. We also illustrate the advantages of \algname{β-SVGD} over \algname{SVGD} by experiments.
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