Sampling in Unit Time with Kernel Fisher-Rao Flow

Aimee Maurais; Youssef Marzouk

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arXiv · 2401.03892

Sampling in Unit Time with Kernel Fisher-Rao Flow

Aimee Maurais·Youssef Marzouk

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Abstract

We introduce a new mean-field ODE and corresponding interacting particle systems (IPS) for sampling from an unnormalized target density. The IPS are gradient-free, available in closed form, and only require the ability to sample from a reference density and compute the (unnormalized) target-to-reference density ratio. The mean-field ODE is obtained by solving a Poisson equation for a velocity field that transports samples along the geometric mixture of the two densities, which is the path of a particular Fisher-Rao gradient flow. We employ a RKHS ansatz for the velocity field, which makes the Poisson equation tractable and enables discretization of the resulting mean-field ODE over finite samples. The mean-field ODE can be additionally be derived from a discrete-time perspective as the limit of successive linearizations of the Monge-Amp\`ere equations within a framework known as sample-driven optimal transport. We introduce a stochastic variant of our approach and demonstrate empirically that our IPS can produce high-quality samples from varied target distributions, outperforming comparable gradient-free particle systems and competitive with gradient-based alternatives.

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BibTeX RIS

Aimee Maurais, Youssef Marzouk. 2024-01-08. Sampling in Unit Time with Kernel Fisher-Rao Flow. https://arxiv.org/abs/2401.03892

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