arXiv:2601.05607cs.LG2026-01ACL被引 1

提出动态混合策略,让大模型推理更稳定高效

Orchestrating Tokens and Sequences: Dynamic Hybrid Policy Optimization for RLVR

  • 融合词级与序列级更新机制,兼顾精准反馈与稳定性
  • 在7个数学推理任务中超越现有方法,性能提升显著
  • 适合需要高精度推理的LLM优化场景,如智能助手

强化学习结合可验证奖励(RLVR)为优化大语言模型的推理能力提供了新路径。然而,现有算法仅关注单一粒度:组相对策略优化(GRPO)使用词级重要性比率,虽保留细粒度信用分配但易受高方差影响;组序列策略优化(GSPO)则采用全局序列级比率,更匹配序列级奖励但牺牲了词级精细反馈。本文提出动态混合策略优化(DHPO),在统一裁剪目标下融合两种比率。通过平均混合与熵引导混合两种机制实现平衡,并引入分支专属裁剪策略,分别限制词级与序列级比率在独立信任区间内,防止异常值主导更新。在涵盖密集型与MoE结构的Qwen3系列模型上,针对七个挑战性数学推理基准的实验表明,DHPO持续优于GRPO与GSPO。代码将在论文录用后开源。

原文摘要 · Abstract (English)

Reinforcement Learning with Verifiable Rewards (RLVR) offers a promising framework for optimizing large language models in reasoning tasks. However, existing RLVR algorithms focus on different granularities, and each has complementary strengths and limitations. Group Relative Policy Optimization (GRPO) updates the policy with token-level importance ratios, which preserves fine-grained credit assignment but often suffers from high variance and instability. In contrast, Group Sequence Policy Optimization (GSPO) applies single sequence-level importance ratios across all tokens in a response that better matches sequence-level rewards, but sacrifices token-wise credit assignment. In this paper, we propose Dynamic Hybrid Policy Optimization (DHPO) to bridge GRPO and GSPO within a single clipped surrogate objective. DHPO combines token-level and sequence-level importance ratios using weighting mechanisms. We explore two variants of the mixing mechanism, including an averaged mixing and an entropy-guided mixing. To further stabilize training, we employ a branch-specific clipping strategy that constrains token-level and sequence-level ratios within separate trust regions before mixing, preventing outliers in either branch from dominating the update. Across seven challenging mathematical reasoning benchmarks, experiments on both dense and MoE models from the Qwen3 series show that DHPO consistently outperforms GRPO and GSPO. We will release our code upon acceptance of this paper.

强化学习推理优化大模型训练

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