REGLAT at HalluScoring-2026: A Multistage Approach for Arabic Hallucination Detection

Nsrin Ashraf, Mariam M. Abdellatif, Mariam Francies, Ahmed M. Fetouh, Hamada Nayel


Abstract
This paper presents a multistage ensemble-based approach developed for the HalluScoring-2026 shared task on Arabic hallucination detection. The proposed system combines three Arabic pretrained language encoders: MARBERTv2, CAMeLBERT, and ARBERT. The diverse linguistic representations captured by these models enable the ensemble to improve the robustness and discriminative capability of hallucination detection compared to the individual encoders. On the development set, the ensemble achieved an AUC-ROC of 0.9413, Macro-F1 of 0.8704, and an AUC-PR of 0.9610, outperforming the individual models. On the official test set, the system achieved an AUC-ROC of 0.7717, Macro-F1 of 0.6576, and an AUC-PR of 0.9181. These results secured the highest overall ranking among all submitted systems, placing our system first in the HalluScoring-2026 shared task. Further analysis reveals substantial variation in detection performance across generator models and linguistic phenomena, with subtle factual deviations, dialectal and culturally specific expressions, and unusually long responses posing particular challenges. Overall, the findings demonstrate the effectiveness of combining distinct Arabic-specific pretrained encoders for robust Arabic hallucination detection.
Anthology ID:
2026.arabicnlp-sharedtasks.142
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:
1146–1153
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.142/
DOI:
Bibkey:
Cite (ACL):
Nsrin Ashraf, Mariam M. Abdellatif, Mariam Francies, Ahmed M. Fetouh, and Hamada Nayel. 2026. REGLAT at HalluScoring-2026: A Multistage Approach for Arabic Hallucination Detection. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 1146–1153, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
REGLAT at HalluScoring-2026: A Multistage Approach for Arabic Hallucination Detection (Ashraf et al., ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.142.pdf