Context Volume Drives Performance: Tackling Domain Shift in Extremely Low-Resource Translation via RAG

Fuente: arXiv
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Autores principales: Setiawan, David Samuel, Merx, Raphaël, Lau, Jey Han
Formato: Preprint
Publicado: 2026
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author Setiawan, David Samuel
Merx, Raphaël
Lau, Jey Han
author_facet Setiawan, David Samuel
Merx, Raphaël
Lau, Jey Han
contents Neural Machine Translation (NMT) models for low-resource languages suffer significant performance degradation under domain shift. We quantify this challenge using Dhao, an indigenous language of Eastern Indonesia with no digital footprint beyond the New Testament (NT). When applied to the unseen Old Testament (OT), a standard NMT model fine-tuned on the NT drops from an in-domain score of 36.17 chrF++ to 27.11 chrF++. To recover this loss, we introduce a hybrid framework where a fine-tuned NMT model generates an initial draft, which is then refined by a Large Language Model (LLM) using Retrieval-Augmented Generation (RAG). The final system achieves 35.21 chrF++ (+8.10 recovery), effectively matching the original in-domain quality. Our analysis reveals that this performance is driven primarily by the number of retrieved examples rather than the choice of retrieval algorithm. Qualitative analysis confirms the LLM acts as a robust "safety net," repairing severe failures in zero-shot domains.
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id arxiv_https___arxiv_org_abs_2601_09982
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Context Volume Drives Performance: Tackling Domain Shift in Extremely Low-Resource Translation via RAG
Setiawan, David Samuel
Merx, Raphaël
Lau, Jey Han
Computation and Language
Artificial Intelligence
Neural Machine Translation (NMT) models for low-resource languages suffer significant performance degradation under domain shift. We quantify this challenge using Dhao, an indigenous language of Eastern Indonesia with no digital footprint beyond the New Testament (NT). When applied to the unseen Old Testament (OT), a standard NMT model fine-tuned on the NT drops from an in-domain score of 36.17 chrF++ to 27.11 chrF++. To recover this loss, we introduce a hybrid framework where a fine-tuned NMT model generates an initial draft, which is then refined by a Large Language Model (LLM) using Retrieval-Augmented Generation (RAG). The final system achieves 35.21 chrF++ (+8.10 recovery), effectively matching the original in-domain quality. Our analysis reveals that this performance is driven primarily by the number of retrieved examples rather than the choice of retrieval algorithm. Qualitative analysis confirms the LLM acts as a robust "safety net," repairing severe failures in zero-shot domains.
title Context Volume Drives Performance: Tackling Domain Shift in Extremely Low-Resource Translation via RAG
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2601.09982