Adversarial Preference Optimization

Human preference alignment is essential to improve the interaction quality of LLMs. Existing aligning methods depend on manually annotated preference data to guide the LLM optimization directions. However, in practice, continuously updating LLMs raises a distribution gap between model-generated samples and human-preferred responses, which hinders model fine-tuning efficiency. To mitigate this issue, previous methods require additional preference annotation on generated samples to adapt the shifted distribution, which consumes a large amount of annotation resources. Targeting more efficient human preference optimization, we propose an adversarial preference optimization (APO) framework, where the LLM agent and the preference model update alternatively via a min-max game. Without additional annotation, our APO method can make a self-adaption to the generation distribution gap through the adversarial learning process. Based on comprehensive experiments, we find APO further enhances the alignment performance of baseline methods in terms of helpfulness and harmlessness. The code is at https://github.com/Linear95/APO.