ArabicMTDiagnostics at AlexandriaX-2026: Detecting and Classifying Errors in Dialectal Arabic Machine Translation Outputs

Sarah Yassine


Abstract
Dialectal Arabic MT error detection asks a sys tem to locate error spans in a machine trans lation and label each with a linguistic error category. It is hard because the dialects lack a standardised orthography and the error cate gories are severely imbalanced. In Subtask 3 of the AlexandriaX 2026 shared task, the in put is an English sentence and its machine translation into one of five Arabic dialects, and the output is character-level error spans with their LQM categories. The central difficulty is collapse onto the majority sociolinguistics class, 58% of training spans, leaving rare cat egories undetected. To address this, we fine tune NileChat-3B-Base with QLoRA on a sin gle 8 GB consumer GPU, casting the task as schema-prompted JSON generation and com bining character-position annotations that let the model copy offsets rather than count them, a category guide with one worked example per error type, and self-consistency decoding merging five samples by character-level union voting. Our system scores 0.3484 Overall on the official test set. We report two negative results: early stopping on validation loss de grades performance, since rare categories are acquired only in later epochs, and fine-tuning on the skewed distribution lowers macro-F1 be low the un-fine-tuned baseline until the cate gory guide is added
Anthology ID:
2026.arabicnlp-sharedtasks.103
Volume:
Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Muhammad Abdul-Mageed, Tamer Elsayed, Houda Bouamor, Samhaa El-Beltagy, Hend Al-Khalifa, Ahmed Abdelali, AbdelRahim Elmadany, Abdellah El Mekki, Kareem Darwish, Sakhar Alkhereyf, Hamzah Luqman, Salam Khalifa, Samar Magdy, Zaid Alyafeai, Injy Hamed, Wajdi Zaghouani, Imed Zitouni
Venue:
ArabicNLP
SIG:
SIGARAB
Publisher:
Association for Computational Linguistics
Note:
Pages:
827–833
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.103/
DOI:
Bibkey:
Cite (ACL):
Sarah Yassine. 2026. ArabicMTDiagnostics at AlexandriaX-2026: Detecting and Classifying Errors in Dialectal Arabic Machine Translation Outputs. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 827–833, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
ArabicMTDiagnostics at AlexandriaX-2026: Detecting and Classifying Errors in Dialectal Arabic Machine Translation Outputs (Yassine, ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.103.pdf