arXiv:2511.21103cs.LGcs.AI2025-11被引 18

提出新解码策略,让扩散语言模型生成更快更准。

From Bits to Rounds: Parallel Decoding with Exploration for Diffusion Language Models

  • 用探索高不确定词提升每轮信息量,打破传统依赖高置信词的瓶颈。
  • 理论证明解码轮数与信息量成正比,与每轮信息预算成反比。
  • 无需训练,可显著减少轮数,适合追求高效生成的场景。

扩散语言模型(DLMs)作为自回归语言模型的有力替代,可通过并行解码实现相近精度与更快推理速度。然而,依赖高置信度标记的标准解码策略存在固有的信息论瓶颈,限制了每轮进展,最终拖慢生成。我们从理论上和实证上证明:优先选择高置信度标记本质上效率低下,因为高概率标记携带的信息量极小,过度依赖会限制每轮有效进展。我们证明了解码轮数必须随样本总信息量(负对数似然)线性增长,且与每轮信息预算成反比,确立了“比特到轮数”的原则。为此,我们提出无需训练的“探索-利用”(ETE)解码策略,结合跨块解码与对高不确定性标记的针对性探索,重塑条件分布,触发一系列高置信预测。实验验证了理论边界,并表明ETE在不牺牲生成质量的前提下,持续减少所需解码轮数,优于仅依赖置信度的基线方法。

原文摘要 · Abstract (English)

Diffusion Language Models (DLMs) have recently emerged as a strong alternative to autoregressive language models (LMs). DLMs offer comparable accuracy with faster inference speed via parallel decoding. However, standard DLM decoding strategies relying on high-confidence tokens encounter an inherent information-theoretic bottleneck that restricts decoding progress and ultimately slows generation. We demonstrate both theoretically and empirically that prioritizing high-confidence tokens is inherently inefficient. High-probability tokens carry negligible information and strictly relying on them limits the effective progress made in each decoding round. We prove that the number of decoding rounds must grow linearly with the sample's total information (negative log-likelihood) and inversely with the per-round information budget, establishing a bits-to-rounds principle. We also propose Explore-Then-Exploit (ETE), a training-free decoding strategy that maximizes information throughput and decoding efficiency. ETE combines cross-block decoding with targeted exploration of high-uncertainty tokens to reshape the conditional distribution and trigger cascades of confident predictions. Experiments verify our theoretical bounds and demonstrate that ETE consistently reduces the required number of decoding rounds compared to confidence-only baselines without compromising generation quality.

扩散模型解码优化语言生成

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