TTLab at AlexandriaX-2026: A Fine-Tuned Surface Tagger for Arabic Machine-Translation Error-Span Detection and Classification

Ali Abusaleh, Bhuvanesh Verma, Alexander Mehler


Abstract
We present TTLab’s submission to the AlexandriaX-2026 Subtask 3 on Arabic MT error span detection and classification. Our system frames the task as token-level classification over surface forms, preserving character offsets to ensure exact alignment with the evaluation metric. To handle severe label imbalance, we employ a focal loss with class weighting and dialect-specific decoding thresholds. Among six Arabic pre-trained encoders, MARBERTv2 achieves the best overall performance of 40.8 and 40.91 on the development and test set, respectively, ranking 3rd out of all participating teams. While our system localizes error spans effectively, classification of rare error types remains challenging, highlighting the need for data augmentation for tail categories.
Anthology ID:
2026.arabicnlp-sharedtasks.98
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:
786–792
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.98/
DOI:
Bibkey:
Cite (ACL):
Ali Abusaleh, Bhuvanesh Verma, and Alexander Mehler. 2026. TTLab at AlexandriaX-2026: A Fine-Tuned Surface Tagger for Arabic Machine-Translation Error-Span Detection and Classification. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 786–792, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
TTLab at AlexandriaX-2026: A Fine-Tuned Surface Tagger for Arabic Machine-Translation Error-Span Detection and Classification (Abusaleh et al., ArabicNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.98.pdf