Back to Basics, Powered by Data: Character-Level Transformers for Robust Chinese Machine-Generated Text Detection

Shengjie Xu, Zhenghao Gao, Rujie Dai, Zijing Li, Xiaoyang Xie, Zehua Lyu


Abstract
Machine-generated text detection remains difficult in Chinese, where systematic benchmarks and large paired corpora are still scarce. We revisit this problem with a compact 4-layer character-level Transformer, trained on a 363.4-million-character Chinese detection corpus, to our knowledge the largest AI-human paired Chinese resource for this task. The resulting data-centric pipeline attains strong scores on Chinese benchmarks and, for the independently trained English variant, state-of-the-art RAID leaderboard numbers that remain stable under 11 RAID adversarial attack types. Ablations expose a double-edged sword role for punctuation: it eases optimization yet encourages overfitting to surface cues; symbol cleaning shifts the model toward deeper syntactic and discourse patterns and improves generalization. Minimal architecture plus rich supervision thus yields compact detectors suitable as a document-level authorship authenticity screen before downstream Chinese text processing; on a laptop RTX 3070 Ti we measure 5.90 x 10^5 tokens/s at under 100 MB VRAM. We present GiantMelon-ZH (Chinese) and GiantMelon-EN (English for RAID): same backbone, disjoint training corpora, transparent data descriptions.
Anthology ID:
2026.aacl-long.265
Volume:
Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venues:
AACL | IJCNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
5879–5903
Language:
URL:
https://aclanthology.org/2026.aacl-long.265/
DOI:
Bibkey:
Cite (ACL):
Shengjie Xu, Zhenghao Gao, Rujie Dai, Zijing Li, Xiaoyang Xie, and Zehua Lyu. 2026. Back to Basics, Powered by Data: Character-Level Transformers for Robust Chinese Machine-Generated Text Detection. In Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers), pages 5879–5903, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
Back to Basics, Powered by Data: Character-Level Transformers for Robust Chinese Machine-Generated Text Detection (Xu et al., AACL-IJCNLP 2026)
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PDF:
https://aclanthology.org/2026.aacl-long.265.pdf