arXiv AI By Seungyoon Lee, Minhyuk Kim, Jungseob Lee, Heuiseok Lim

Language Chain in Alignment: Cross-Lingual Ranking Preference Optimization

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arXiv AI
Aug 28

Language Chain in Alignment: Cross-lingual Ranking Preference Optimization

The paper introduces Cross‑lingual Ranking Preference Optimization (CRPO), a framework that uses high‑quality English preference data to improve alignment of large language models in other languages. CRPO builds a hierarchical structure over parallel preference pairs, jointly optimizing intra‑ and inter‑lingual preferences and providing a relative ranking signal beyond binary comparisons. Experiments on five languages show consistent gains in instruction‑following and knowledge utilization, with robust performance across different weighting schemes and improved reward margins and log‑probabilities of desirable responses.

By Seungyoon Lee, Minhyuk Kim, Jungseob Lee, Heuiseok Lim
arXiv AI
Sep 3

CroCo: Cross-Lingual Contrastive Preference Tuning on Self-Generations

CroCo introduces cross‑lingual contrastive preference tuning on self‑generations, extending prior English‑only methods to 14 high‑ and low‑resource languages. A reward model trained solely on English preferences, applied to a multilingual base, yields effective within‑language rankings and improves performance in both monolingual and multilingual settings without catastrophic forgetting. The approach requires on‑policy data; off‑policy responses and online preference optimization offer limited gains, yet on structured tasks CroCo matches or surpasses the base model in most languages, and on open‑ended generation it wins 28/30 judge evaluations across 15 languages.

By Mike Zhang, Ali Basirat, Desmond Elliott
arXiv AI
Aug 26

Preference Data Selection for Mitigating the Alignment Tax in Large Language Models

The paper introduces BALIGN, a balanced data selection strategy designed to reduce catastrophic forgetting—referred to as the alignment tax—in large language models during preference-based alignment. By analyzing preference optimization gradients, the authors identify three data-centric features that influence parameter drift: the reference model's log-probability margin, token length differences between chosen and rejected responses, and TF‑IDF similarity to general capability corpora. BALIGN aggregates these features into a composite risk score to filter out high-risk preference samples, thereby preserving foundational capabilities while maintaining alignment gains with minimal computational overhead.

By Minsu Kim, Jianxun Lian, Xing Xie, Steven Euijong Whang