NLPLab at ArGuard Shared Tasks: Balancing Confidence Scores for Fine-Grained Classification of Unsafe Arabic Prompts Across Harm Domains

Olumide Ebenezer Ojo, Hamid T. Ogunlenu, Olaronke Oluwayemisi Adebanji, Tolulope Olalekan Abiola, Hiram Calvo, Alexander Gelbukh


Abstract
This paper presents the CIC system for ArGuard 2026 Subtask B2, which classifies unsafe Arabic prompts into one of seven harm domains. Our system combines four complementary components: a fine-tuned CAMeLBERT-Mix model, a modified-Huber stochastic gradient descent classifier, a character-level nearest-neighbor model, and a character class-centroid similarity model. On the development set, we achieved a Macro-F1 score of 0.916 and an accuracy of 0.923. On the test set, the proposed model achieved an accuracy of 0.766, a macro precision of 0.760, a macro recall of 0.763, and a Macro-F1 of 0.751. The results show that combining contextual transformer representations, lexical features, and retrieval-based similarity signals can improve fine-grained harmful-prompt classification.
Anthology ID:
2026.arabicnlp-sharedtasks.56
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:
437–442
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.56/
DOI:
Bibkey:
Cite (ACL):
Olumide Ebenezer Ojo, Hamid T. Ogunlenu, Olaronke Oluwayemisi Adebanji, Tolulope Olalekan Abiola, Hiram Calvo, and Alexander Gelbukh. 2026. NLPLab at ArGuard Shared Tasks: Balancing Confidence Scores for Fine-Grained Classification of Unsafe Arabic Prompts Across Harm Domains. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 437–442, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
NLPLab at ArGuard Shared Tasks: Balancing Confidence Scores for Fine-Grained Classification of Unsafe Arabic Prompts Across Harm Domains (Ojo et al., ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.56.pdf