Meta_Labs at StanceEval-2026: Calibrated Routing and Pseudo-Label Self-Training for Cross-Target Arabic Stance Detection

Maryam Gheysari, Behnam Nazari, Fatemeh Rahimzadeh


Abstract
We present CaRPS, our system for Track 1 of StanceEval-2026. CaRPS combines a target-conditioned encoder with an LLM-based labeling and verification process to handle targets that are not seen during encoder fine-tuning. The encoder takes both the target and the tweet as input, while the LLM is used to generate labels and verify difficult predictions. These LLM-generated labels can then be used as pseudo-labeled data to further fine-tune the encoder, with the goal of gradually reducing the need for LLM calls. On the development leaderboard, our target-conditioned encoder alone achieves 87.19% Favg2, 76.56% Favg3, and 85.30% accuracy. For the official evaluation, we used adversarial LLM prompting for the target not seen during encoder fine-tuning, achieving 82.89% Favg2, 62.67% Favg3, and 78.98% accuracy. Additional experiments show that adversarial verification improves stance and sarcasm classification over one-shot prompting, while pseudo-label self-training helps adapt the encoder to a held-out target. Overall, CaRPS explores a practical combination of efficient encoder-based prediction and LLM-based labeling and verification for Arabic stance detection.
Anthology ID:
2026.arabicnlp-sharedtasks.78
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:
617–624
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.78/
DOI:
Bibkey:
Cite (ACL):
Maryam Gheysari, Behnam Nazari, and Fatemeh Rahimzadeh. 2026. Meta_Labs at StanceEval-2026: Calibrated Routing and Pseudo-Label Self-Training for Cross-Target Arabic Stance Detection. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 617–624, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Meta_Labs at StanceEval-2026: Calibrated Routing and Pseudo-Label Self-Training for Cross-Target Arabic Stance Detection (Gheysari et al., ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.78.pdf