arXiv:2409.17545cs.CLcs.AI2024-09

根据数据对齐程度动态调节参考模型干预强度,提升模型对齐效果

Modulated Intervention Preference Optimization (MIPO): Keep the Easy, Refine the Difficult

  • 依据数据与参考模型的对齐度,动态调整干预强度
  • 在Alpaca Eval 2.0和MT-Bench上均优于DPO
  • 适合参考模型与数据差距较大的场景

偏好优化方法通常以预训练的SFT模型作为参考模型。在RLHF和DPO中,通过正则化项防止策略模型偏离参考模型分布,避免生成异常响应。当参考模型已良好对齐数据或仅需微调时,该方法有效;但若参考模型与数据严重不匹配,正则化反而会阻碍对齐。本文提出模态干预偏好优化(MIPO),根据数据与参考模型的对齐程度动态调节干预强度:对齐好时加强干预,防止策略模型过度偏离;对齐差时减弱干预,允许更充分的训练。在Mistral-7B和Llama3-8B上,基于Alpaca Eval 2.0与MT-Bench的实验表明,MIPO在多种评估场景下持续优于DPO。

原文摘要 · Abstract (English)

Preference optimization methods typically begin training with a well-trained SFT model as a reference model. In RLHF and DPO, a regularization term is used during the preference optimization process to prevent the policy model from deviating too far from the reference model's distribution, thereby avoiding the generation of anomalous responses. When the reference model is already well-aligned with the given data or only requires slight adjustments, this approach can produce a well-aligned model. However, if the reference model is not aligned with the given data and requires significant deviation from its current state, a regularization term may actually hinder the model alignment. In this study, we propose \textbf{Modulated Intervention Preference Optimization (MIPO)} to address this issue. MIPO modulates the degree of intervention from the reference model based on how well the given data is aligned with it. If the data is well-aligned, the intervention is increased to prevent the policy model from diverging significantly from reference model. Conversely, if the alignment is poor, the interference is reduced to facilitate more extensive training. We compare the performance of MIPO and DPO using Mistral-7B and Llama3-8B in Alpaca Eval 2.0 and MT-Bench. The experimental results demonstrate that MIPO consistently outperforms DPO across various evaluation scenarios.

偏好优化强化学习模型对齐

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