SNAPP: Segment-Level Neural Alignment Post-Processing for Low-Resource Parallel Sentence Mining

Niklas Hettich, Shu Okabe, Alexander Fraser


Abstract
Machine Translation (MT) for low-resource languages has been challenging so far, mainly due to the small size or lack of parallel sentences. Parallel sentence mining and filtering are two automatic approaches which aim to identify and curate such resources. Yet, they usually rely on multilingual representation as a backend, which is known to be of poorer quality for low-resource language pairs, leading to the introduction of noisy pairs. We devise SNAPP, a post-processing pipeline which combines a segment-level filtering technique with an unsupervised neural aligner to remove highly similar but non-parallel sentence pairs. Modular components further enable more specific adaptation to the language pair under consideration. We evaluate filtering performance on three language pairs of varying typological distance. Finally, we show improvement on the downstream MT performance with our post-processing pipeline for the two harder language pairs.
Anthology ID:
2026.wmt-main.14
Volume:
Proceedings of the Eleventh Conference on Machine Translation
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Barry Haddow, Tom Kocmi, Philipp Koehn, Christof Monz
Venues:
WMT | WS
SIG:
SIGMT
Publisher:
Association for Computational Linguistics
Note:
Pages:
239–253
Language:
URL:
https://aclanthology.org/2026.wmt-main.14/
DOI:
Bibkey:
Cite (ACL):
Niklas Hettich, Shu Okabe, and Alexander Fraser. 2026. SNAPP: Segment-Level Neural Alignment Post-Processing for Low-Resource Parallel Sentence Mining. In Proceedings of the Eleventh Conference on Machine Translation, pages 239–253, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
SNAPP: Segment-Level Neural Alignment Post-Processing for Low-Resource Parallel Sentence Mining (Hettich et al., WMT 2026)
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PDF:
https://aclanthology.org/2026.wmt-main.14.pdf