LahjaMT at AlexandriaX-2026: A Context-Aware English-to-Dialectal Arabic Machine Translation System with Lightweight Routing of LoRA Experts

Mohamed Abdallah, Samhaa R. El-Beltagy


Abstract
Dialectal Arabic dialogue translation requires modeling both regional variation and conversational context under uneven supervision. We introduce LahjaMT, a compact system for translating English dialogue into thirteen country-level Arabic varieties. LahjaMT adapts the 3.12B-parameter NileChat-3B-Base model with LoRA, conditions translation on dialogue history and metadata, and routes each dialect to a checkpoint–prompt expert selected on the held-out selection set. The constrained system shares one backbone across all varieties; the unconstrained system changes only the Libyan and Sudanese routes, replacing them with specialists trained on auxiliary data. LahjaMT ranked second in the constrained track with 28.30 spBLEU and third in the unconstrained track with 28.54 spBLEU.
Anthology ID:
2026.arabicnlp-sharedtasks.107
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:
857–863
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.107/
DOI:
Bibkey:
Cite (ACL):
Mohamed Abdallah and Samhaa R. El-Beltagy. 2026. LahjaMT at AlexandriaX-2026: A Context-Aware English-to-Dialectal Arabic Machine Translation System with Lightweight Routing of LoRA Experts. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 857–863, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
LahjaMT at AlexandriaX-2026: A Context-Aware English-to-Dialectal Arabic Machine Translation System with Lightweight Routing of LoRA Experts (Abdallah & El-Beltagy, ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.107.pdf