NAMAA at StanceEval-2026: From Encoder and Decoder Model Fine-Tuning to Data-Centric Retrieval-Augmented In-Context Learning for Arabic Stance Detection

Abdelbasset Djamai, Hassan Barmandah, Nour Qandos, Samar Ahmad, Omer Nacar


Abstract
Stance detection identifies an author’s position toward a specified target, yet Arabic social-media text remains challenging because stance is often implicit and shaped by dialect, sarcasm, informal expression, and culturally specific references. StanceEval-2026 evaluates this problem in two transfer settings: a related target within a seen thematic domain (Track 1) and entirely unseen topics (Track 2). We compare four modeling strategies: single-task Arabic encoder fine-tuning, multi-task learning with sentiment and sarcasm supervision, 4-bit QLoRA adaptation of the ALLaM-7B model, and Retrieval-Augmented In-Context Learning (RAG-ICL) with frozen large language models (LLMs). Our strongest single-backend configuration is a data-centric RAG-ICL pipeline combining label-balanced retrieval, hashtag and negation adaptation, text cleaning, similarity filtering, and target descriptions. A majority-vote ensemble of this configuration across three LLM backends obtains official Favg2 scores of 0.8719 on Track 1 and 0.9016 on Track 2, ranking 3rd and 7th, respectively. Under the shared-task test conditions, the retrieval-based systems substantially outperform the supervised systems evaluated here, particularly on Track 2.
Anthology ID:
2026.arabicnlp-sharedtasks.74
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:
573–588
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.74/
DOI:
Bibkey:
Cite (ACL):
Abdelbasset Djamai, Hassan Barmandah, Nour Qandos, Samar Ahmad, and Omer Nacar. 2026. NAMAA at StanceEval-2026: From Encoder and Decoder Model Fine-Tuning to Data-Centric Retrieval-Augmented In-Context Learning for Arabic Stance Detection. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 573–588, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
NAMAA at StanceEval-2026: From Encoder and Decoder Model Fine-Tuning to Data-Centric Retrieval-Augmented In-Context Learning for Arabic Stance Detection (Djamai et al., ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.74.pdf