arXiv Machine Learning

Minimax Optimality of Score-Entropy Discrete Diffusion

arXiv Machine Learning
Oct 16

Score Mismatch and Set-Constrained Sampling in Zero-Shot Conditional Discrete Diffusion

The paper presents a theoretical analysis of score mismatch in discrete diffusion models, deriving a KL divergence upper bound that quantifies the bias introduced when the training and target distributions differ. It examines partial-observation constraints such as text infilling and sentence completion, showing that the Conditional SEDD sampler can incur a bias that grows with dimension, vocabulary size, and compatibility. To mitigate this, the authors propose a Randomized Hard Clamping (RHC) sampler for coordinatewise set constraints, demonstrating through experiments that it effectively reduces bias and improves sampling performance.

By Renxiang Huang, Yuchen Liang, Yingbin Liang, Ness Shroff, Lifeng Lai
arXiv Machine Learning
Jul 20

Diffusion models recover accurate mixture weights despite score function insensitivity

arXiv:2607. 15485v1 Announce Type: new Abstract: Score-based generative models exhibit a puzzling behavior: they often appear to cover all modes of a target multimodal distribution and yet may fail to learn the correct relative mode amplitudes, which can be interpreted as mixture weights.

By Andrew Dennehy, Ramchandran Muthukumar, Rebecca Willett, Nisha Chandramoorthy
arXiv Statistics ML
Oct 2

Sample complexity bounds for categorical Markov random fields via Discrete Diffusions

The paper presents sample complexity bounds for sampling high‑dimensional categorical distributions with local dependence using discrete diffusions. It introduces a pinning decomposition of the discrete score, enabling a weight‑sharing neural score learner combined with τ‑leaping for efficient end‑to‑end sampling. The authors derive explicit guarantees that depend on vocabulary size, MRF interaction order, and sample size, and demonstrate that weight‑sharing networks outperform fully connected ones on Potts, Ising, and tree‑structured models.

By Shivam Kumar, Nabarun Deb