QuadCore at ArGuard Shared Tasks: Ensembling Arabic Encoders with Dialect Conditioning for Harm-Domain Classification

Sidratul Muntaha, Sabila Anzum, Umme Saima Tonny, Maimuna Tabassum


Abstract
We describe the QuadCore submission to Sub task B2 of the ArGuard 2026 shared task, which asks systems to assign an Arabic prompt addressed to a large language model to one of seven harm domains. Our system is a soft-voting ensemble of three Arabic en coders with complementary pre-training cor pora- MARBERTv2, CAMeLBERT-DA and AraBERTv02-Twitter- each fine-tuned under two random seeds, with the annotated dialect prepended to the prompt as a textual condition ing prefix; it uses no external data, no augmen tation and no generative models. It reached 0.7665 macro-F1 on the official test set, rank ing 4th of the 16 teams that submitted to the subtask. Using the gold labels released after the evaluation period, we then show that this sin gle number conflates two regimes: on the first 4,809 test items, whose label prior, dialect mix and lexical profile match the training data, the same predictions reach 0.9044 macro-F1, while on a contiguous final block of 1,170 items they collapse to 0.2073. That block is entirely Mod ern Standard Arabic, contains no adult-content instance, and its nearest-neighbour label agree ment with the training set is 0.1829 against 0.7777 elsewhere- close to the 1/7 chance rate. A substantial portion of our system’s errors on the official test set is therefore attributable to this shift rather than to the difficulty of harm domain classification itself.
Anthology ID:
2026.arabicnlp-sharedtasks.53
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:
419–425
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.53/
DOI:
Bibkey:
Cite (ACL):
Sidratul Muntaha, Sabila Anzum, Umme Saima Tonny, and Maimuna Tabassum. 2026. QuadCore at ArGuard Shared Tasks: Ensembling Arabic Encoders with Dialect Conditioning for Harm-Domain Classification. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 419–425, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
QuadCore at ArGuard Shared Tasks: Ensembling Arabic Encoders with Dialect Conditioning for Harm-Domain Classification (Muntaha et al., ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.53.pdf