Stein Variational Gradient Descent (SVGD), introduced in [LW16], is a deterministic interactingparticle method for sampling from a target probability measure π e V, only requiring access to V. In the mean-field and continuous-time limit, the distribution of particles converges to a flow (ρt) in the space of probability measures that solves a variant of the Fokker-Planck equation with a velocity field smoothed by weighted convolution with a positive definite kernel [LLN19]. This flow can be interpreted as the gradient flow of the relative entropy H( |π) with respect to a "kernelized" Wasserstein metric [Liu17]. The goal of this paper is to investigate the convergence of (ρt) towards π. To this end, we focus on the model case of Riesz kernels of order s on the d-dimensional torus Td. This is a family of translation-invariant kernels whose Fourier coefficients decay as |ξ| 2s. The parameter s hence directly controls the "smoothing strength" of the interaction; in particular, continuous kernels correspond to s > d/2, C1 kernels to s > (d+1)/2, and C2 kernels to s > (d+2)/2. What is known: qualitative weak convergence The starting point of convergence analyses is the energy dissipation formula [Liu17] d dt H(ρt|π) = Is(ρt|π), (1.1) Authors are listed in alphabetical order.

Stein V ariational Gradient Descent (SVGD) is a nonparametric particle-based deterministic sampling algorithm.

Although the population (i.e, infinite-particle) limit dynamics of SVGD is well characterized, its behavior in the finite-particle regime is far less understood.

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Neural transport augmented sampling, firstintroduced byParnoandMarzouk (2018),isageneral method for using normalizing flows to sample from a given densityπ. Thus, samples can be generated fromπ(θ)by running MCMC chain in theZ-space and pushing these samples onto theΘ-space usingT. Neural transport augmented samplers havebeen subsequently extended by Hoffman etal. In this paper, we proposed equivariant Stein variational gradient descent algorithm for sampling fromdensities thatareinvarianttosymmetry transformations. Another contributionofourworkis subsequently using this equivariant sampling method to efficiently train equivariant energy based models forprobabilistic modeling andinference.

Subsequently,wedefineequivariant energy based models to model invariant densities that are learned using contrastivedivergence.