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Uncertainty-Penalized Reinforcement Learning from Human Feedback with Diverse Reward LoRA Ensembles

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arxiv 2401.00243 v1 pith:RIUB5RAC submitted 2023-12-30 cs.LG

Uncertainty-Penalized Reinforcement Learning from Human Feedback with Diverse Reward LoRA Ensembles

classification cs.LG
keywords lorarewardrlhfdiversehumanuncertaintyensemblesmodels
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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Reinforcement learning from human feedback (RLHF) emerges as a promising paradigm for aligning large language models (LLMs). However, a notable challenge in RLHF is overoptimization, where beyond a certain threshold, the pursuit of higher rewards leads to a decline in human preferences. In this paper, we observe the weakness of KL regularization which is commonly employed in existing RLHF methods to address overoptimization. To mitigate this limitation, we scrutinize the RLHF objective in the offline dataset and propose uncertainty-penalized RLHF (UP-RLHF), which incorporates uncertainty regularization during RL-finetuning. To enhance the uncertainty quantification abilities for reward models, we first propose a diverse low-rank adaptation (LoRA) ensemble by maximizing the nuclear norm of LoRA matrix concatenations. Then we optimize policy models utilizing penalized rewards, determined by both rewards and uncertainties provided by the diverse reward LoRA ensembles. Our experimental results, based on two real human preference datasets, showcase the effectiveness of diverse reward LoRA ensembles in quantifying reward uncertainty. Additionally, uncertainty regularization in UP-RLHF proves to be pivotal in mitigating overoptimization, thereby contributing to the overall performance.

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Forward citations

Cited by 8 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Internal Pluralism and the Limits of Pairwise Comparisons

    cs.AI 2026-07 conditional novelty 7.0

    Under internal pluralism, forced local pairwise comparisons erase inseparable priorities and distort conflicted answers, while allowing indecision reports can sharply reduce queries needed to learn preference weights.

  2. Functional-level Uncertainty Quantification for Calibrated Fine-tuning on LLMs

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  3. Wasserstein Distributionally Robust Regret Optimization for Reinforcement Learning from Human Feedback

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    Wasserstein distributionally robust regret optimization for RLHF admits a promptwise water-filling solution and a GRPO-compatible sampled bonus that mitigates over-optimization better than value-robust DRO.

  4. A Unifying Lens on Reward Uncertainty in RLHF

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