AUC DL Lab at AraSeg Shared Task 2026: Syntax-Aware Graphs, Bidirectionalized Decoders, and Encoders for Arabic Sentence Segmentation

Mohamed Sabry, Yehia Ragab


Abstract
The AUC DL Lab system addresses the AraSeg 2026 shared task on Arabic sentence segmentation across four conditions: paragraph-aware (PA), no-paragraph (NP), no-punctuation paragraph-aware (NOPNX-PA), and no-punctuation no-paragraph (NOPNXNP), in both the closed and open tracks. We cast segmentation as imbalanced word-level boundary classification and pair fine-tuned Arabic encoders with two complementary architectures: HDP-GRAPH, which models syntactic structure via dependency-graph message passing, and a quantized decoder-only LLM using Just Pass Twice (JPT) with QLoRA for contextual boundary classification. Predictions are calibrated and combined through differential-evolution ensemble weighting. On the blind test set, our closed track systems reach 94.5, 90.8, 89.2, and 86.0 F1 (ranking 5th, 6th, 6th, 7th), and our open-track systems reach 94.6, 90.9, 89.7, and 86.0 F1 (ranking 3rd, 4th, 4th, 5th) on PA, NP, NOPNX-PA, and NOPNX-NP, respectively. Architectural diversity grows more valuable as punctuation and paragraph cues are removed, while external data yields only marginal gains once in-domain coverage is adequate.
Anthology ID:
2026.arabicnlp-sharedtasks.119
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:
961–970
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.119/
DOI:
Bibkey:
Cite (ACL):
Mohamed Sabry and Yehia Ragab. 2026. AUC DL Lab at AraSeg Shared Task 2026: Syntax-Aware Graphs, Bidirectionalized Decoders, and Encoders for Arabic Sentence Segmentation. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 961–970, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
AUC DL Lab at AraSeg Shared Task 2026: Syntax-Aware Graphs, Bidirectionalized Decoders, and Encoders for Arabic Sentence Segmentation (Sabry & Ragab, ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.119.pdf