TokenRatio: Principled Token-Level Preference Optimization via Ratio Matching 事件

TokenRatio: Principled Token-Level Preference Optimization via Ratio Matching arXiv:2605.12288v3 Announce Type: replace Abstract: Direct Preference Optimization (DPO) is a widely used RL-free method for aligning language models from pairwise preferences, but it models preferences over full sequences even though generation is driven by per-token decisions. Existing token-level extensions typically decompose a sequence-level Bradley-Terry objective across timesteps, leaving per-prefix (state-wise