BNEM: A Boltzmann Sampler Based on Bootstrapped Noised Energy Matching
RuiKang OuYang, Bo Qiang, Jos\'e Miguel Hern\'andez-Lobato

TL;DR
This paper introduces BNEM, a neural sampler based on bootstrapped noised energy matching, which efficiently generates independent samples from Boltzmann distributions with improved variance and robustness.
Contribution
The paper proposes a novel diffusion-based neural sampler with a bootstrapping technique, achieving lower variance and better performance than existing methods.
Findings
BNEM achieves state-of-the-art performance on GMM and DW-4 tasks.
BNEM demonstrates increased robustness compared to related methods.
Theoretical analysis shows lower variance of the proposed sampler.
Abstract
Developing an efficient sampler capable of generating independent and identically distributed (IID) samples from a Boltzmann distribution is a crucial challenge in scientific research, e.g. molecular dynamics. In this work, we intend to learn neural samplers given energy functions instead of data sampled from the Boltzmann distribution. By learning the energies of the noised data, we propose a diffusion-based sampler, Noised Energy Matching, which theoretically has lower variance and more complexity compared to related works. Furthermore, a novel bootstrapping technique is applied to NEM to balance between bias and variance. We evaluate NEM and BNEM on a 2-dimensional 40 Gaussian Mixture Model (GMM) and a 4-particle double-well potential (DW-4). The experimental results demonstrate that BNEM can achieve state-of-the-art performance while being more robust.
Peer Reviews
Decision·Submitted to ICLR 2025
The paper describes the method very clearly. In particular, figure 1 is quite concise. Moreover, it shows proof that the improvements suggested are indeed improvements. Section 3 is well written, and the score vs. energy section contribution is valuable. The results are strong and show improvement over other methods for the toy problems.
While the paper clearly shows improvement over previous neural sampling methods, it still makes little or no progress on the fundamental challenge of scaling to larger systems. The authors acknowledge this, but it ultimately make this an incremental improvement, not a transformational one.
The MS attacks an important problem and improves upon the state of the art. The solution is original (to the best of this reviewer's knowledge) and provides theoretical as well as empirical reasons to prefer their proposal over alternatives.
(1) On the GMM-40 task, the manuscript's version of iDEM (Fig. 2) is visibly inferior to the one in the original paper (Akhound-Sadegh et al, Fig. 3), which is much closer to ground truth. Something similar is true of the energy histogram for LJ-55 (Fig. 3 in this MS, Fig. 4 in op. cit.). Can the authors explain these discrepancies? (2) For DW-4, LJ-13, and LJ-55, the improvement in Wasserstein-2 distance provided by NEM and BNEM over iDEM appears marginal (Table 1). Considering the addition
The paper is generally well-written and easy to follow. The authors provide enough background to make the paper easy to understand. The topic of diffusion-based samplers is also an important and interesting topic with applications in many domains. Additionally, improving the MC estimator of the score when we have access to the energy and not data is, in my opinion, very well-motivated.
**Novelty and Motivation**: Although the NEM algorithm is a simple reparametrization of the estimator in iDEM, the paper analyzes the implications of an energy or score parametrization and shows that this simple change can lead to a better estimator. The more novel algorithm is BNEM, however, the paper does not provide enough experimental results to support the benefit of this method (see my notes under Experiments). - Theoretical Limitations: The work makes several claims regarding the varia
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Taxonomy
TopicsEnergy Load and Power Forecasting · Fuel Cells and Related Materials · Diverse Musicological Studies
