Title: Multi-Sample Preference Optimization for Generative Model Alignment
Primary area: foundation or frontier models, including LLMs
Keywords: Generative Models, LLM, Diffusion, RLHF, Preference Optimization

Abstract: Recent advancements in generative models, particularly large language models (LLMs) and diffusion models, have been driven by extensive pre-training on large datasets followed by post-training. However, current post-training methods such as reinforcement learning from human feedback (RLHF) and direct alignment from preference methods (DAP) primarily utilize single-sample comparisons. These approaches often fail to capture critical characteristics such as generative diversity and bias, which are more accurately assessed through multiple samples. To address these limitations, we introduce a novel approach that extends post-training to include multi-sample comparisons. To achieve this, we propose Multi-sample Direct Preference Optimization (mDPO) and Multi-sample Identity Preference Optimization (mIPO). These methods improve traditional DAP methods by focusing on group-wise characteristics. Empirically, we demonstrate that multi-sample comparison is more effective in optimizing collective characteristics~(e.g., diversity and bias) for generative models than single-sample comparison. Additionally, our findings suggest that multi-sample comparisons provide a more robust optimization framework, particularly for dataset with label noise.

TL;DR: We introduce multi-sample comparisons for generative models, improving diversity, bias, and robustness over traditional single-sample methods.