Corpora Generation for Urdu Grammatical Error Correction
Summary
Urdu has many millions of speakers but almost no annotated parallel data. As a result, automatic grammatical error correction (GEC) for this language has received little study, and neural seq2seq models lack training material. The authors propose a pipeline that synthesizes training pairs without manual annotation and without rules written specifically for Urdu. First, "before and after" sentence pairs are selected from the edit history of the Urdu Wikipedia. These pairs are analyzed with Stanza and a custom alignment algorithm inspired by ERRANT. Each error is stored as a morphosyntactic "core", meaning the changed word together with its nearest neighbors. These patterns are then transferred to grammatically correct sentences, which are artificially corrupted, and error frequencies are adjusted to match the natural distribution. This produced the UrduGEC-Synthetic corpus. Separately, a gold-standard test set, UrduGEC-Gold, was compiled from students' examination papers. Models such as mT0 and NLLB perform noticeably better on the Gold set after fine-tuning on the synthetic data. The authors believe the method can be transferred to other Indo-Aryan languages that have POS taggers and treebanks.
Key points
- Wiki-Edits Dataset: about 240K sentence pairs from the edit history of the Urdu Wikipedia. The latest revision is treated as correct and the one before it as erroneous. After cleaning, the corpus retains only grammatical edits.
- Error annotation: Stanza identifies POS tags, lemmas and morphological features. A closed vocabulary built from the UD 2.12 treebank checks words for OOV status so that purely orthographic corrections can be discarded. The alignment divides edits into I/D/S (insertion, deletion, substitution). Instead of the standard Levenshtein distance, it uses a linguistically motivated cost function.
- Resources: UrduGEC-Synthetic contains 1.27 million sentence pairs. UrduGEC-Gold consists of digitized, anonymized student papers and is small. Both datasets are released on Hugging Face, and the pipeline code is on GitHub.
- Result: after fine-tuning on UrduGEC-Synthetic, the mT0 and NLLB models substantially improved their results on UrduGEC-Gold.
- Limitations: the core covers a three-word context, so the approach does not capture non-local or structural errors. Urdu has no counterpart to ERRANT, so a direct comparison with methods such as Choe et al. (2019) is not possible.
Cite
@inproceedings{ahad2026corpora,
title = {{Corpora Generation for Urdu Grammatical Error Correction}},
author = {Ahad, Syed and Ezzi, Burhanuddin Aliasghar and Hussain, Muhammad Arsalan and Kumar, Sandesh and Samad, Abdul},
booktitle = {Findings of the Association for Computational Linguistics: ACL 2026},
year = {2026},
doi = {10.18653/v1/2026.findings-acl.2156},
url = {https://doi.org/10.18653/v1/2026.findings-acl.2156}
}References
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