Step-KTO: Optimizing Mathematical Reasoning through Stepwise Binary Feedback

Yen-Ting Lin, Di Jin, Tengyu Xu, Tianhao Wu, Sainbayar Sukhbaatar, Chen Zhu, Yun He, Yun-Nung Chen, Jason E Weston, Yuandong Tian, Arash Rahnama, Sinong Wang, Hao Ma, Han Fang


Abstract
Large language models (LLMs) have recently demonstrated remarkable success in mathematical reasoning. Despite progress in methods like chain-of-thought prompting and self-consistency sampling, these advances often focus on final correctness without ensuring that the underlying reasoning process is coherent and reliable. This paper introduces Step-KTO, a training framework that combines process-level and outcome-level binary feedback to guide LLMs toward more trustworthy reasoning trajectories. By providing binary evaluations for both the intermediate reasoning steps and the final answer, Step-KTO encourages the model to adhere to logical progressions rather than relying on superficial shortcuts. Our experiments on challenging mathematical benchmarks show that Step-KTO significantly improves both final answer accuracy and the quality of intermediate reasoning steps. For example, on the MATH-500 dataset, Step-KTO achieves a notable improvement in Pass@1 accuracy over strong baselines. These results highlight the promise of integrating stepwise process feedback into LLM training, paving the way toward more interpretable and dependable reasoning capabilities.
Anthology ID:
2025.mathnlp-main.2
Volume:
Proceedings of The 3rd Workshop on Mathematical Natural Language Processing (MathNLP 2025)
Month:
November
Year:
2025
Address:
Suzhou, China
Editors:
Marco Valentino, Deborah Ferreira, Mokanarangan Thayaparan, Leonardo Ranaldi, Andre Freitas
Venues:
MathNLP | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
15–33
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URL:
https://preview.aclanthology.org/ingest-emnlp/2025.mathnlp-main.2/
DOI:
Bibkey:
Cite (ACL):
Yen-Ting Lin, Di Jin, Tengyu Xu, Tianhao Wu, Sainbayar Sukhbaatar, Chen Zhu, Yun He, Yun-Nung Chen, Jason E Weston, Yuandong Tian, Arash Rahnama, Sinong Wang, Hao Ma, and Han Fang. 2025. Step-KTO: Optimizing Mathematical Reasoning through Stepwise Binary Feedback. In Proceedings of The 3rd Workshop on Mathematical Natural Language Processing (MathNLP 2025), pages 15–33, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
Step-KTO: Optimizing Mathematical Reasoning through Stepwise Binary Feedback (Lin et al., MathNLP 2025)
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https://preview.aclanthology.org/ingest-emnlp/2025.mathnlp-main.2.pdf