arXiv Machine Learning By Shiyuan Zhang, Xuheng Li, Qiwei Di, Quanquan Gu

Query-Efficient Rejection Sampling for Parallel Masked Diffusion

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The paper introduces the Single-Increment Rejection Sampler (SIRS) to improve query efficiency in parallel masked diffusion models (MDMs). SIRS estimates the log acceptance probability using only one randomly sampled increment, then applies a Bernoulli factory to decide accept/reject outcomes. By Rao‑Blackwellizing each increment and bounding the KL‑divergence, SIRS reduces bias while maintaining parallel decoding performance.

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