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arXiv 2602.03102cs.LG
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基于共识组的相对策略优化用于文本生成

Consensus Group Relative Policy Optimization for Text Generation

Nara Institute of Science and Technology(奈良科学技术大学);Advanced Telecommunications Research Institute International(国际电信研究中心)

Yuki Ichihara, Yuu Jinnai, Kaito Ariu, Eiji Uchibe

AI总结:

C-GRPO通过将共识效用作为组相对目标,实现无需黄金参考的文本生成解码,有效提升性能并减少计算开销。

摘要:

许多强大的文本生成解码方法遵循样本和重新排序的范式:它们生成多个候选方案,在样本之间达成共识后对每个方案进行评分,然后返回最佳方案。尽管有效,但这些方法在推理过程中由于重复采样和评分而产生高昂的计算成本。以往试图减少推理时间计算通常依赖于黄金参考、教师标签或精心编纂的偏好数据,增加了数据集构建的努力和对高保真度奖励模型的需求。我们提出了共识组相对策略优化(C-GRPO),通过在GRPO中将共识效用作为组相对目标来公式化,将最小贝叶斯风险(MBR)解码提炼到训练中。C-GRPO仅需一个效用函数和策略样本,不需要黄金参考或显式偏好标签。在理想条件下,我们证明C-GRPO的目标函数在方向上与MBR解码下预期效用目标的梯度一致,从而保证了收敛性。在机器翻译(WMT 2024)和文本摘要(XSum)的实验中,C-GRPO成功实现了与MBR解码相当的性能,而无需相关的推理时间开销,同时优于无参考基础方法。

英文摘要:

Many strong decoding methods for text generation follow a sample-and-rerank paradigm: they draw multiple candidates, score each under a utility (reward) function using consensus across samples, and return the best one. Although effective, these methods incur high computational costs during inference due to repeated sampling and scoring. Prior attempts to amortize inference-time computation typically rely on gold references, teacher labels, or curated preference data, increasing dataset construction effort and the demand for high-fidelity reward models. We propose Consensus Group Relative Policy Optimization (C-GRPO), which distills Minimum Bayes Risk (MBR) decoding into training by formulating the consensus utility as a group-relative objective within GRPO. C-GRPO requires only a utility function and policy samples, without gold references or explicit preference labels. Under ideal conditions, we show that the objective function of C-GRPO is directionally aligned with the gradient of the expected-utility objective underlying MBR decoding, leading to a convergence guarantee. Experiments on machine translation (WMT 2024) and text summarization (XSum) demonstrate that C-GRPO successfully achieves performance comparable to MBR decoding without the associated inference-time overhead, while outperforming reference-free baseline methods.

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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