Lossy Orthography and Linguistic Inference: Computational Approaches to Arabic Rasm Restoration

Maged S. Al-shaibani, Irfan Ahmad


Abstract
Restoring dots to dotless Arabic text, historically known as _rasm_, is a foundational yet underexplored problem in Arabic NLP. While Arabic diacritization focuses on recovering omitted vowels, rasm restoration addresses a deeper level of orthographic ambiguity in which consonantal distinctions themselves are absent from the written text. Beyond its linguistic and historical significance, the task has applications in representation learning, tokenization, OCR, manuscript digitization, information retrieval, and content moderation. In this paper, we present a large-scale comparative study of Arabic rasm restoration across statistical, neural, pretrained, and prompt-based paradigms. We evaluate n-gram language models, BiLSTMs and Transformers trained from scratch, pretrained character-level CANINE models, and large language models (LLMs) using few-shot prompting. Our experiments were conducted on a diverse corpus exceeding 431M words spanning social media, news, religious texts, poetry, and academic writing. Results show that Transformer models achieve the best overall performance while remaining computationally efficient. BiLSTMs perform competitively, and classical n-gram models remain surprisingly strong despite their simplicity. In contrast, modern LLMs perform substantially below specialized models, with flagship systems only matching the performance of a 4-gram baseline. These findings position rasm restoration as a challenging benchmark for contextual orthographic inference and a natural extension of Arabic diacritization research.
Anthology ID:
2026.emnlp-main.2258
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
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Pages:
51351–51371
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2258/
DOI:
Bibkey:
Cite (ACL):
Maged S. Al-shaibani and Irfan Ahmad. 2026. Lossy Orthography and Linguistic Inference: Computational Approaches to Arabic Rasm Restoration. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 51351–51371, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Lossy Orthography and Linguistic Inference: Computational Approaches to Arabic Rasm Restoration (Al-shaibani & Ahmad, EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.2258.pdf