Text-Preserving Lossy Text Compression: A Study of Strategic Deletion and LLM Reconstruction

Yuchun Zou, Junhong Tong, Jun Li


Abstract
Traditional lossless text compression preserves every byte, but its gains on natural language are often modest. We study lossy semantic text compression, where the encoder strategically deletes parts of the text and a large language model (LLM) reconstructs the original from the retained skeleton. We benchmark a progression of deletion strategies, from character-level and word-level rules driven by word length or corpus frequency to surprisal-based and hybrid rules that require a neural encoder, and reach three findings. First, deletion by corpus word frequency is a strong low-cost baseline: a static frequency lookup remains competitive with far more expensive semantic methods. Second, semantic and hybrid methods gain most at mild-to-moderate compression, whereas at the lowest retention rate frequency-based deletion matches them and keeps more named entities. Third, QLoRA fine-tuning yields a compact local decoder that, once adapted, is competitive with zero-shot Gemini 2.0 Flash. Additional English and Chinese experiments show that the framework transfers across domains, while the best deletion rule remains dataset-dependent.
Anthology ID:
2026.aacl-long.107
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:
2349–2382
Language:
URL:
https://aclanthology.org/2026.aacl-long.107/
DOI:
Bibkey:
Cite (ACL):
Yuchun Zou, Junhong Tong, and Jun Li. 2026. Text-Preserving Lossy Text Compression: A Study of Strategic Deletion and LLM Reconstruction. 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 2349–2382, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
Text-Preserving Lossy Text Compression: A Study of Strategic Deletion and LLM Reconstruction (Zou et al., AACL-IJCNLP 2026)
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PDF:
https://aclanthology.org/2026.aacl-long.107.pdf