arXiv Machine Learning
4d ago

Reflected Anchored Langevin Algorithms

The paper introduces Reflected Anchored Langevin Dynamics (RALD), a reflected diffusion that can converge to non‑differentiable target distributions on constrained domains. By employing a smooth anchored reference potential and scaling the drift and noise covariance with a state‑dependent factor, the authors derive an Euler‑Maruyama discretization with projection, yielding the Reflected Anchored Langevin Monte Carlo (RALMC) algorithm. Explicit convergence bounds and iteration complexity in the 2‑Wasserstein distance are proven, and numerical experiments confirm the theoretical predictions and empirical performance.

By Changwei Tu, Xiaoyu Wang, Yingli Wang, Xicheng Zhang, Lingjiong Zhu
arXiv Machine Learning
Jun 17

Randomized Midpoint Method for Log-Concave Sampling under Constraints

arXiv:2405. 15379v3 Announce Type: replace-cross Abstract: In this paper, we study the problem of sampling from log-concave distributions supported on convex and compact sets, with a particular focus on the randomized midpoint discretization of both overdamped and kinetic Langevin diffusions in constrained domains.

By Yifeng Yu, Shijie Zhang, Lu Yu
arXiv Machine Learning
Aug 27

Improved Analysis for Hessian-free High-resolution Monte Carlo Sampling

The paper introduces Hessian-free high-resolution (HFHR) dynamics, an extension of underdamped Langevin dynamics that incorporates reversible position diffusion for sampling in machine learning. It provides an explicit quantitative contraction rate under a position Poincaré inequality, weighted Hessian and Laplacian bounds, and a compact Sobolev embedding, even when the potential is non‑convex. For the HFHR Monte Carlo algorithm, a path‑space Girsanov argument yields a non‑asymptotic convergence bound and an explicit iteration complexity in total variation distance, improving on previous HFHR results and demonstrating benefits of a positive diffusion parameter through numerical experiments.

By Wujun Lv, Xiaoyu Wang, Yingli Wang, Lingjiong Zhu
arXiv Machine Learning
3d ago

Accelerating Non-Smooth and Heavy-Tailed Sampling

The paper introduces non‑reversible anchored Langevin dynamics (NALD) and its reflected variant (NRALD) for sampling target distributions that may be non‑smooth and heavy‑tailed, both in Euclidean space and on constrained domains. By adding a circulation drift through a divergence‑free skew‑symmetric matrix field and a stream potential, the methods preserve the target distribution without needing density derivatives, admit a random‑time‑change representation, and can be applied with normal reflection on bounded domains. The authors demonstrate that breaking reversibility leads to faster convergence to the target distribution, as shown by finite‑time non‑asymptotic analysis, large‑deviations results, and asymptotic variance reduction, with numerical experiments confirming the algorithms’ efficiency.

By Pervez Ali, Xiaoyu Wang, Yingli Wang, Lingjiong Zhu