Qahera at IslamicEval 2026: Corpus-Grounded Retrieval and Iterative Harness Search with a 4B-Parameter LLM for Islamic Citation Verification

Hazem Ajlan, Mohamed Mohamed


Abstract
We describe the Qahera system for the four IslamicEval 2026 subtasks: (1) detecting Qur’an/Hadith citation spans in LLM-generated Islamic answers, (2) judging citation authenticity, (3) correcting inauthentic citations against reference corpora, and (4) judging whether an authentic citation answers the question asked. Under a 13B-parameter open-model constraint, running entirely on free Kaggle GPUs, we combine a lightweight token-classification model with character-level auxiliary features (Sub-task 1), corpus-grounded fuzzy retrieval (Sub-tasks 2–3), and a 4B-parameter instruction-tuned LLM (Gemma-3-4B) used only where retrieval alone cannot discriminate (Subtasks 3–4). Rather than hand-designing LLM prompts once, we develop them through an iterative propose-evaluate-diagnose search loop that reads full prediction traces after every candidate and hunts for systematic biases before each change. This surfaces small-model failure modes – a near-universal “reject” bias in isolated yes/no verification, and an “always name something” bias in numbered-list prompts – that would otherwise silently cap performance, and shows that validating candidates on small subsets can be actively misleading. Our final system reaches 0.9716 F1 (Subtask 1), 0.906 accuracy (Subtask 2), 0.773 accuracy (Subtask 3), and 0.673 macro-F1 (Subtask 4) on the official test sets.
Anthology ID:
2026.arabicnlp-sharedtasks.134
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:
1088–1092
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.134/
DOI:
Bibkey:
Cite (ACL):
Hazem Ajlan and Mohamed Mohamed. 2026. Qahera at IslamicEval 2026: Corpus-Grounded Retrieval and Iterative Harness Search with a 4B-Parameter LLM for Islamic Citation Verification. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 1088–1092, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Qahera at IslamicEval 2026: Corpus-Grounded Retrieval and Iterative Harness Search with a 4B-Parameter LLM for Islamic Citation Verification (Ajlan & Mohamed, ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.134.pdf