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arXiv 2310.06147cs.LGcs.AI
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大语言模型时代的强化学习:什么是必要的?什么是需要的?关于RLHF、提示工程及其超越的强化学习视角

Reinforcement Learning in the Era of LLMs: What is Essential? What is needed? An RL Perspective on RLHF, Prompting, and Beyond

University of Cambridge(剑桥大学)

Hao Sun

AI总结:

本文从强化学习视角阐明RLHF的原理,指出其本质为在线逆强化学习,并探讨了RLHF优于SFT的原因、奖励模型作为反馈代理的泛化性及PPO的稳定性优势。

摘要:

近年来,大型语言模型(LLMs)的进步引起了广泛关注,并催生了如ChatGPT和GPT-4等成功产品。它们遵循指令并提供无害、有帮助且诚实(3H)回应的能力,在很大程度上可归功于从人类反馈中进行的强化学习(RLHF)技术。在本文中,我们旨在将传统强化学习的研究与LLM研究中使用的强化学习技术联系起来。通过讨论强化学习为何、何时以及如何表现出色,来阐明这一技术。此外,我们探索了可能受益于或有助于RLHF研究的潜在未来方向。\n重点要点:\n1. RLHF是带有离线演示数据的在线逆强化学习。\n2. RLHF优于SFT,因为模仿学习(和逆强化学习)通过缓解复合误差问题而优于行为克隆(BC)。\n3. RLHF中的奖励模型(RM)步骤生成了昂贵的人类反馈的代理,这一见解可以推广到其他LLM任务,如提示评估和优化,其中反馈也是昂贵的。\n4. RLHF中的策略学习比传统IRL中研究的问题更具挑战性,因为其动作维度高且反馈稀疏。\n5. PPO相对于离策略基于价值的方法的主要优势在于其从(几乎)在策略数据和保守的策略更新中获得的稳定性。

英文摘要:

Recent advancements in Large Language Models (LLMs) have garnered wide attention and led to successful products such as ChatGPT and GPT-4. Their proficiency in adhering to instructions and delivering harmless, helpful, and honest (3H) responses can largely be attributed to the technique of Reinforcement Learning from Human Feedback (RLHF). In this paper, we aim to link the research in conventional RL to RL techniques used in LLM research. Demystify this technique by discussing why, when, and how RL excels. Furthermore, we explore potential future avenues that could either benefit from or contribute to RLHF research. Highlighted Takeaways: 1. RLHF is Online Inverse RL with Offline Demonstration Data. 2. RLHF $>$ SFT because Imitation Learning (and Inverse RL) $>$ Behavior Cloning (BC) by alleviating the problem of compounding error. 3. The RM step in RLHF generates a proxy of the expensive human feedback, such an insight can be generalized to other LLM tasks such as prompting evaluation and optimization where feedback is also expensive. 4. The policy learning in RLHF is more challenging than conventional problems studied in IRL due to their high action dimensionality and feedback sparsity. 5. The main superiority of PPO over off-policy value-based methods is its stability gained from (almost) on-policy data and conservative policy updates.

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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