@inproceedings{rao-etal-2026-decepticons,
title = "Decepticons-{IIITH} : Morphology-Aware Lexicon Filtering of Back-Translated Data for Low-Resource {E}nglish-to-{I}ndic Translation",
author = "Rao, Soujanya and
Taneja, Sakhil and
Chaitanya, Krishna and
Mamidi, Radhika",
editor = "Haddow, Barry and
Kocmi, Tom and
Koehn, Philipp and
Monz, Christof",
booktitle = "Proceedings of the Eleventh Conference on Machine Translation",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.wmt-main.160/",
pages = "2207--2212",
ISBN = "979-8-89176-474-3",
abstract = "This study tackles the WMT 2026 Low-Resource Indic Language Translation task, covering English {\textrightarrow} Assamese, Bodo, Mizo and Nagamese. Low-resource languages lack parallel corpora of sufficient size and quality to train machine translation models. To address this challenge, we propose Morphology-Aware Lexicon Filtering of Back-Translated data to generate good-quality parallel corpora. Initially, monolingual text from publicly available sources is back-translated to English with an NLLB-200-3.3B model fine-tuned on the official training data. To filter this synthetic data, we introduce MALM (Morphology-Aware Lexicon Matching), a filter that checks whether words from a bilingual lexicon are preserved in a translation, using Morfessor stems to handle rich morphology and edit-distance matching to handle borrowed words. For our primary method, training occurs in two stages: fine-tuning on filtered synthetic (back-translated) data followed by fine-tuning on the official parallel data. Whereas for the contrastive method, we are only fine-tuning on the official parallel data. We fine-tune the NLLB-200-3.3B model for Assamese, Mizo, Nagamese and the IndicTrans2-1B model for Bodo. Our primary systems ranked first among primary submissions on two Category-2 pairs viz. English {\textrightarrow} Bodo and English {\textrightarrow} Nagamese. On Nagamese, where only 2,000 official sentence pairs exist, of the two methods we used, the primary system improved by a BLEU score of 8.33."
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<abstract>This study tackles the WMT 2026 Low-Resource Indic Language Translation task, covering English → Assamese, Bodo, Mizo and Nagamese. Low-resource languages lack parallel corpora of sufficient size and quality to train machine translation models. To address this challenge, we propose Morphology-Aware Lexicon Filtering of Back-Translated data to generate good-quality parallel corpora. Initially, monolingual text from publicly available sources is back-translated to English with an NLLB-200-3.3B model fine-tuned on the official training data. To filter this synthetic data, we introduce MALM (Morphology-Aware Lexicon Matching), a filter that checks whether words from a bilingual lexicon are preserved in a translation, using Morfessor stems to handle rich morphology and edit-distance matching to handle borrowed words. For our primary method, training occurs in two stages: fine-tuning on filtered synthetic (back-translated) data followed by fine-tuning on the official parallel data. Whereas for the contrastive method, we are only fine-tuning on the official parallel data. We fine-tune the NLLB-200-3.3B model for Assamese, Mizo, Nagamese and the IndicTrans2-1B model for Bodo. Our primary systems ranked first among primary submissions on two Category-2 pairs viz. English → Bodo and English → Nagamese. On Nagamese, where only 2,000 official sentence pairs exist, of the two methods we used, the primary system improved by a BLEU score of 8.33.</abstract>
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%0 Conference Proceedings
%T Decepticons-IIITH : Morphology-Aware Lexicon Filtering of Back-Translated Data for Low-Resource English-to-Indic Translation
%A Rao, Soujanya
%A Taneja, Sakhil
%A Chaitanya, Krishna
%A Mamidi, Radhika
%Y Haddow, Barry
%Y Kocmi, Tom
%Y Koehn, Philipp
%Y Monz, Christof
%S Proceedings of the Eleventh Conference on Machine Translation
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-474-3
%F rao-etal-2026-decepticons
%X This study tackles the WMT 2026 Low-Resource Indic Language Translation task, covering English → Assamese, Bodo, Mizo and Nagamese. Low-resource languages lack parallel corpora of sufficient size and quality to train machine translation models. To address this challenge, we propose Morphology-Aware Lexicon Filtering of Back-Translated data to generate good-quality parallel corpora. Initially, monolingual text from publicly available sources is back-translated to English with an NLLB-200-3.3B model fine-tuned on the official training data. To filter this synthetic data, we introduce MALM (Morphology-Aware Lexicon Matching), a filter that checks whether words from a bilingual lexicon are preserved in a translation, using Morfessor stems to handle rich morphology and edit-distance matching to handle borrowed words. For our primary method, training occurs in two stages: fine-tuning on filtered synthetic (back-translated) data followed by fine-tuning on the official parallel data. Whereas for the contrastive method, we are only fine-tuning on the official parallel data. We fine-tune the NLLB-200-3.3B model for Assamese, Mizo, Nagamese and the IndicTrans2-1B model for Bodo. Our primary systems ranked first among primary submissions on two Category-2 pairs viz. English → Bodo and English → Nagamese. On Nagamese, where only 2,000 official sentence pairs exist, of the two methods we used, the primary system improved by a BLEU score of 8.33.
%U https://aclanthology.org/2026.wmt-main.160/
%P 2207-2212
Markdown (Informal)
[Decepticons-IIITH : Morphology-Aware Lexicon Filtering of Back-Translated Data for Low-Resource English-to-Indic Translation](https://aclanthology.org/2026.wmt-main.160/) (Rao et al., WMT 2026)
ACL