FUSE : A Ridge and Random Forest-Based Metric for Evaluating MT in Indigenous Languages

Rahul Raja, Arpita Vats


Abstract
This paper presents the winning submission of the RaaVa team to the AmericasNLP 2025 Shared Task 3 on Automatic Evaluation Metrics for Machine Translation (MT) into Indigenous Languages of America, where our system ranked first overall based on average Pearson correlation with the human annotations. We introduce Feature-Union Scorer (FUSE) for Evaluation, FUSE integrates Ridge regression and Gradient Boosting to model translation quality. In addition to FUSE, we explore five alternative approaches leveraging different combinations of linguistic similarity features and learning paradigms. FUSE Score highlights the effectiveness of combining lexical, phonetic, semantic, and fuzzy token similarity with learning-based modeling to improve MT evaluation for morphologically rich and low-resource languages. MT into Indigenous languages poses unique challenges due to polysynthesis, complex morphology, and non-standardized orthography. Conventional automatic metrics such as BLEU, TER, and ChrF often fail to capture deeper aspects like semantic adequacy and fluency. Our proposed framework, formerly referred to as FUSE, incorporates multilingual sentence embeddings and phonological encodings to better align with human evaluation. We train supervised models on human-annotated development sets and evaluate held-out test data. Results show that FUSE consistently achieves higher Pearson and Spearman correlations with human judgments, offering a robust and linguistically informed solution for MT evaluation in low-resource settings.
Anthology ID:
2025.americasnlp-1.8
Volume:
Proceedings of the Fifth Workshop on NLP for Indigenous Languages of the Americas (AmericasNLP)
Month:
May
Year:
2025
Address:
Albuquerque, New Mexico
Editors:
Manuel Mager, Abteen Ebrahimi, Robert Pugh, Shruti Rijhwani, Katharina Von Der Wense, Luis Chiruzzo, Rolando Coto-Solano, Arturo Oncevay
Venues:
AmericasNLP | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
77–83
Language:
URL:
https://preview.aclanthology.org/Author-page-Marten-During-lu/2025.americasnlp-1.8/
DOI:
Bibkey:
Cite (ACL):
Rahul Raja and Arpita Vats. 2025. FUSE : A Ridge and Random Forest-Based Metric for Evaluating MT in Indigenous Languages. In Proceedings of the Fifth Workshop on NLP for Indigenous Languages of the Americas (AmericasNLP), pages 77–83, Albuquerque, New Mexico. Association for Computational Linguistics.
Cite (Informal):
FUSE : A Ridge and Random Forest-Based Metric for Evaluating MT in Indigenous Languages (Raja & Vats, AmericasNLP 2025)
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PDF:
https://preview.aclanthology.org/Author-page-Marten-During-lu/2025.americasnlp-1.8.pdf