LLMTrace: A Corpus for Classification and Fine-Grained Localization of AI-Written Text

Irina Tolstykh, Aleksandra Tsybina, Sergey Yakubson, Maksim Kuprashevich


Abstract
The widespread use of human-like text from Large Language Models (LLMs) necessitates the development of robust detection systems. However, progress is limited by a critical lack of suitable training data; existing datasets are often generated with outdated models, are predominantly in English, and fail to address the increasingly common scenario of mixed human-AI authorship. Crucially, while some datasets address mixed authorship, none provide the character-level annotations required for the precise localization of AI-generated segments within a text. To address these gaps, we introduce LLMTrace, a new large-scale, bilingual (English and Russian) corpus for AI-generated text detection. Constructed using a diverse range of modern proprietary and open-source LLMs, our dataset is designed to support two key tasks: traditional full-text binary classification (human vs. AI) and AI-generated interval detection, facilitated by character-level annotations. We believe LLMTrace will serve as a vital resource for training and evaluating the next generation of more nuanced and practical AI detection models.
Anthology ID:
2026.findings-emnlp.1951
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
41585–41622
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1951/
DOI:
Bibkey:
Cite (ACL):
Irina Tolstykh, Aleksandra Tsybina, Sergey Yakubson, and Maksim Kuprashevich. 2026. LLMTrace: A Corpus for Classification and Fine-Grained Localization of AI-Written Text. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 41585–41622, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
LLMTrace: A Corpus for Classification and Fine-Grained Localization of AI-Written Text (Tolstykh et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1951.pdf