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arXiv 2602.03496cs.LG
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前瞻路径似然优化用于扩散大语言模型

Lookahead Path Likelihood Optimization for Diffusion LLMs

Institute for Artificial Intelligence, Peking University(人工智能研究院,北京大学);School of Computing, National University of Singapore(计算学院,新加坡国立大学);School of Intelligence Science and Technology, Peking University(智能科学与技术学院,北京大学)

Xuejie Liu, Yap Vit Chun, Yitao Liang, Anji Liu

AI总结:

本文提出POKE-SMC方法,通过优化路径似然提升扩散大语言模型的解屏蔽路径准确性,实验表明在同等计算开销下,平均提升2%-3%的准确性。

摘要:

扩散大语言模型(dLLMs)支持任意顺序的生成,但其推理性能严重依赖于解屏蔽顺序。现有策略依赖于启发式方法,通过贪婪优化局部置信度,为识别全局一致且准确的解屏蔽路径提供有限的指导。为弥合这一差距,我们引入路径对数似然(Path LL),一个轨迹条件化的目标,与下游准确性高度相关,并能够原理性地选择解屏蔽路径。为了在推理时间优化Path LL,我们提出POKE,一个高效的值估计器,可预测部分解码轨迹的预期未来Path LL。然后,我们将此前瞻信号整合到POKE-SMC中,一个基于序列蒙特卡罗的搜索框架,用于动态识别最优解屏蔽路径。在六个推理任务上的广泛实验表明,POKE-SMC一致提高了准确性,在与LLaDA模型相当的推理开销下,平均比强大的解码时间扩展基线提高了2%至3%,并推进了准确性-计算量帕累托前沿。

英文摘要:

Diffusion Large Language Models (dLLMs) support arbitrary-order generation, yet their inference performance critically depends on the unmasking order. Existing strategies rely on heuristics that greedily optimize local confidence, offering limited guidance for identifying unmasking paths that are globally consistent and accurate. To bridge this gap, we introduce path log-likelihood (Path LL), a trajectory-conditioned objective that strongly correlates with downstream accuracy and enables principled selection of unmasking paths. To optimize Path LL at inference time, we propose POKE, an efficient value estimator that predicts the expected future Path LL of a partial decoding trajectory. We then integrate this lookahead signal into POKE-SMC, a Sequential Monte Carlo-based search framework for dynamically identifying optimal unmasking paths. Extensive experiments across 6 reasoning tasks show that POKE-SMC consistently improves accuracy, achieving 2%--3% average gains over strong decoding-time scaling baselines at comparable inference overhead on LLaDA models and advancing the accuracy--compute Pareto frontier.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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