提出单向策略优化方法,让大模型持续自我进化
One-Way Policy Optimization for Self-Evolving LLMs

- 用验证器决定更新方向,参考模型仅调幅度,避免惩罚过度
- 实验显示超越DAPO等基线,在多个任务上实现持续性能提升
- 适合需要长期自我改进的智能体系统,如自动推理与决策
基于可验证奖励的强化学习(RLVR)已成为提升大语言模型推理能力的有力范式。然而,二元验证器奖励稀疏常导致训练效率低和优化不稳定。现有方法通常对齐参考策略施加逐标记约束,但这类约束会无差别惩罚偏离,当策略试图超越参考时可能反转验证器判断,抑制性能提升。为此,我们提出单向策略优化(OWPO),其核心是将优化方向与更新幅度解耦。在OWPO中,验证器决定更新方向,参考策略仅用于调整更新幅度。具体地,对表现较差的偏离执行加速对齐,对表现更优的偏离实施收益锁定。此外,通过迭代更新参考策略,实现‘棘轮效应’,持续固化进步。实验表明,OWPO显著优于DAPO、OPD、MOPD等强基线,突破固定先验瓶颈,实现无需外部参考模型的持续自演化。
原文摘要 · Abstract (English)
Reinforcement Learning with Verifiable Rewards (RLVR) has become a promising paradigm for scaling reasoning capabilities of Large Language Models (LLMs). However, the sparsity of binary verifier rewards often leads to low efficiency and optimization instability. To stabilize training, existing methods typically impose token-level constraints relative to a reference policy. We identify that such constraints penalize deviations indiscriminately; this can flip verifier-determined direction when the policy attempts to outperform the reference, thereby suppressing gains. To resolve this, we propose One-Way Policy Optimization (OWPO), a method based on the principle of decoupling optimization direction from update magnitude. In OWPO, the verifier dictates the update direction, while the reference policy serves only to adjust the magnitude. Specifically, OWPO applies asymmetric reweighting: it performs Accelerated Alignment for inferior deviations (where the policy lags behind the reference) and Gain Locking for superior deviations (where the policy surpasses the reference). Furthermore, by incorporating iterative reference updates, OWPO creates a ``Ratchet Effect'' that continuously consolidates gains. Experimental results demonstrate that OWPO outperforms strong baselines, including DAPO, OPD, and MOPD, breaking the bottleneck of fixed priors to enable continuous self-evolution without reliance on external reference models.
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