Enhancing Long-Context Reasoning via Verifiable Atomic Skills

Yanling Xiao, Huaibing Xie, Guoliang Zhao, Shihan Dou, Nantao Zheng, Shaolei Wang, Yiting Liu, Cheng Zhang, Pluto Zhou, Zhisong Zhang, Lemao Liu


Abstract
Long-context reasoning remains a critical challenge for Large Language Models (LLMs). Current research typically focuses on curating specialized training data by treating long-context reasoning as a monolithic task, yet it is challenging to verify its quality due to its internal cognitive complexity. In this paper, we propose a paradigm shift: viewing long-context reasoning as a hierarchical spectrum of core atomic skills. To operationalize this, we present an Anchor-based Reasoning (AbR) pipeline that automatically synthesizes strictly verifiable training data for each skill, thereby enabling reliable quality. Diagnostic analyses confirm that proficiency in these atomic skills strongly predicts general long-context reasoning performance. By training exclusively on a highly compact set of merely four thousand synthesized samples with Reinforcement Learning (RL), we explicitly sharpen these foundational capabilities. Extensive experiments across six challenging benchmarks demonstrate that this targeted RL causally delivers robust and generalizable performance gains, outperforming DeepSeek-R1-distill-32B by an average margin of 7.7% (improving from 46.3% to 54.0%). Furthermore, in-depth ablations reveal that these skills operate synergistically, establishing a scalable, data-efficient, and verifiable path to advancing long-context reasoning.
Anthology ID:
2026.emnlp-main.1513
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
34516–34532
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1513/
DOI:
Bibkey:
Cite (ACL):
Yanling Xiao, Huaibing Xie, Guoliang Zhao, Shihan Dou, Nantao Zheng, Shaolei Wang, Yiting Liu, Cheng Zhang, Pluto Zhou, Zhisong Zhang, and Lemao Liu. 2026. Enhancing Long-Context Reasoning via Verifiable Atomic Skills. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 34516–34532, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Enhancing Long-Context Reasoning via Verifiable Atomic Skills (Xiao et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1513.pdf