Think in Sentences: Explicit Sentence Boundaries Enhance Language Model’s Capabilities

Zhichen Liu, Yongyuan Li, Yang Xu


Abstract
Researchers have explored ways to improve large language models (LLMs)’ capabilities via dummy token insertion in contexts. However, existing works focus solely on the dummy tokens themselves, but failed to leverage the inherent sentence-level structure of natural language. This is a critical oversight, as LLMs acquire linguistic capabilities through exposure to human-generated texts, which are inherently structured at the sentence level. Motivated by the gap, we proposed a method that inserts delimiters at sentence boundaries. Our method not only integrates dummy tokens into contexts, but also enables LLMs with sentence-by-sentence processing behavior during reasoning. Two approaches are proposed: (1). In-context learning and (2). Supervised fine-tuning are experimented from 7B LLMs to 600B Deepseek-V3. Experimental results demonstrate consistent improvements in various tasks, with notable gains of up to 7.7% on GSM8k and 12.5% on DROP. Furthermore, LLMs fine-tuned via our strategy further incorporate sentence awareness into their inner representations. Our work establishes a simple yet effective technique for enhancing LLM’s capabilities, offering promising directions for cognitive-inspired LLM enhancement paradigm.
Anthology ID:
2026.acl-long.104
Volume:
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
2275–2288
Language:
URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.104/
DOI:
Bibkey:
Cite (ACL):
Zhichen Liu, Yongyuan Li, and Yang Xu. 2026. Think in Sentences: Explicit Sentence Boundaries Enhance Language Model’s Capabilities. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 2275–2288, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
Think in Sentences: Explicit Sentence Boundaries Enhance Language Model’s Capabilities (Liu et al., ACL 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.104.pdf
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