ZHR at StanceEval-2026: Surface-Matched Synthetic Demonstrations and Metric-Aware Decoding for Arabic Cross-Target Stance Detection

Mahmoud Zaher, Mohamed Bahgat, Mahmoud Alshrief


Abstract
We describe the ZHR system for both tracks of StanceEval-2026, Arabic stance detection on Mawqif-XT, where Track 1 evaluates on seen targets and Track 2 on unseen ones. The system combines fine-tuned Arabic encoders, a few-shot classifier that retrieves labelled examples for a served instruction model, and generative models adapted with LoRA, and turns their blended probabilities into labels with a threshold rule that abstains to None unless one stance class is probable enough, with thresholds fixed on the development split. We report the whole sequence of experiments, including eight that lowered Favg2 and were not adopted. The main finding is that transfer to a new target is carried by the demonstrations, the labelled examples retrieved into the prompt, rather than by the model itself. Generated on-target tweets in the example pool gave the largest gain on both tracks, matching the surface form of the test tweets helped where the target has a distinctive style, and doubling the examples hurt. Our official results are Favg2 0.896 with accuracy 0.855 on Track 1, and Favg2 0.940 with accuracy 0.922 on Track 2. The strongest official baselines reach 0.8425 on the Track 1 development set and 0.7475 on the Track 2 test set.
Anthology ID:
2026.arabicnlp-sharedtasks.83
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:
656–666
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.83/
DOI:
Bibkey:
Cite (ACL):
Mahmoud Zaher, Mohamed Bahgat, and Mahmoud Alshrief. 2026. ZHR at StanceEval-2026: Surface-Matched Synthetic Demonstrations and Metric-Aware Decoding for Arabic Cross-Target Stance Detection. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 656–666, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
ZHR at StanceEval-2026: Surface-Matched Synthetic Demonstrations and Metric-Aware Decoding for Arabic Cross-Target Stance Detection (Zaher et al., ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.83.pdf