DDO-RM: Distribution-Level Policy Improvement after Reward Learning
Recent theory suggests that reward-model-first methods can be more sample-efficient than direct policy fitting when the reward function is statistically simpler than the induced policy. We propose DDO-RM, a finite-candidate decision-optimization method that converts reward scores into an explicit target distribution. Unlike PPO-based RLHF or DPO, DDO-RM performs a KL-regularized mirror-descent update to project the policy toward a reward-improved distribution over a candidate set. Preliminary experiments on Pythia-410M show that DDO-RM outperforms DPO in pair accuracy (0.52 to 0.56) and mean margin (0.13 to 0.53). Our framework provides a principled connection between reward learning and ...
| Authors | Tiantian Zhang, Jierui Zuo, Michael Chen et al. |
|---|---|
| Primary category | stat.ML |
| Published | 13 April 2026 |
| Last updated at source | 29 April 2026 |
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