Reinforcement Learning from Human Feedback (RLHF) has been pivotal in enabling Large Language Models (LLMs) to effectively follow instructions and produce meaningful alignment by leveraging human preference data. Traditionally, RLHF involves generating responses to a query and using a separate reward model to assign a score to the entire completion. This approach, however, presents challenges, as it provides a single, sparse reward at the end of a sequence, making optimization difficult for the model, in which both training and generation occur auto-regressively at token levels. While recent methods have attempted to address this by assigning token-level discrete or continuous rewards, these often rely on either a trained credit assignment model or AI annotators, which raises concerns about the quality and reliability of the token-level rewards. In this paper, we propose T-REG, which utilizes both sequence-level and token-level rewards for preference optimization. T-REG employs self-generated token-level rewards, derived through opposite prompting, as a weak supervision signal to guide the model in distributing sequence-level rewards at the token level, thereby achieving more effective token-level credit assignment and improving alignment performance. Experiments on the instruction following benchmarks, including Alpaca Eval 2 and Arena-Hard, show that our method consistently outperforms baseline methods by up to 3.8% and 4.4%, respectively.

Advancements in Large Language Models (LLMs) have significantly enhanced instruction-following capabilities. However, most Instruction Fine-Tuning (IFT) datasets are predominantly in English, limiting model performance in other languages. Traditional methods for creating multilingual IFT datasets—such as translating existing English IFT datasets or converting existing NLP datasets into IFT datasets by templating—struggle to capture linguistic nuances and ensure prompt (instruction) diversity. To address this issue, we propose a novel method for collecting multilingual IFT datasets that preserves linguistic naturalness and ensures prompt diversity. This approach leverages English-focused LLMs, monolingual corpora, and a scoring function to create high-quality, diversified IFT datasets in multiple languages. Experiments demonstrate that LLMs finetuned using these IFT datasets show notable improvements in both generative and discriminative tasks, indicating enhanced language comprehension by LLMs in non-English contexts. Specifically, on the multilingual summarization task, LLMs using our IFT dataset achieved 17.57% and 15.23% improvements over LLMs fine-tuned with translation-based and template-based datasets, respectively.