Solodiscourse at Daleel 2026: Lexically-Augmented Focal-Loss Ensembling for Arabic Argumentative Discourse Unit Classification

Turab Hussain Usmani


Abstract
We describe our submission to Task 1 (Argumentative Discourse Unit Classification) of the Daleel 2026 shared task on Arabic argument mining, in the closed track. Given a paragraph from an Arabic editorial or debate transcript, the task is to predict the multi-label set of argumentative functions it contains, drawn from six classes: common ground, assumption, testimony, statistics, anecdote, and other. Our system fine-tunes a pretrained Arabic encoder, comparing AraBERT, MARBERT, and CAMeLBERT-mix, augmented with a small side-channel of hand-crafted lexical features motivated directly by the task’s class definitions (e.g., reporting verbs for testimony, digit/percentage patterns for statistics), trained with a class-balanced focal loss and combined into a 5-fold cross-validation ensemble; CAMeLBERT-mix was selected as the final encoder for all submitted configurations. In the dev phase, our Both-domain configuration achieved an overall macro-F1 of 0.5600 (editorial 0.4350, debate 0.4900). On the official test-phase Codabench leaderboard, our Both-domain configuration achieved an overall macro-F1 of 0.5265 (editorial 0.3838, debate 0.4943), ranking 10th; our Editorial-only configuration reached an overall macro-F1 of 0.4544 (editorial 0.3249, debate 0.4509). We report two findings grounded in these results: overall (pooled) macro-F1 consistently exceeds the macro-F1 computed on either genre subset alone, and our editorial-only model unexpectedly scores higher macro-F1 on the out-of-domain debate subset than on its own in-domain editorial subset. We discuss both as likely artifacts of per-class support sparsity at the smaller genre-subset scale rather than genuine cross-domain superiority, though we did not conduct a formal ablation study or systematic error analysis to confirm this, which we flag as the primary limitation of this report. Our code is available at https://github.com/turab-usmani/daleel-task1-closedtrack.
Anthology ID:
2026.arabicnlp-sharedtasks.171
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:
1375–1379
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.171/
DOI:
Bibkey:
Cite (ACL):
Turab Hussain Usmani. 2026. Solodiscourse at Daleel 2026: Lexically-Augmented Focal-Loss Ensembling for Arabic Argumentative Discourse Unit Classification. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 1375–1379, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Solodiscourse at Daleel 2026: Lexically-Augmented Focal-Loss Ensembling for Arabic Argumentative Discourse Unit Classification (Usmani, ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.171.pdf