Diacritic Restoration for Low-Resource Indigenous Languages: Case Study with Bribri and Cook Islands Māori

Fuente: arXiv
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Auteurs principaux: Coto-Solano, Rolando, Li, Daisy, Ferraz, Manoela Teleginski, Sasse, Olivia, Krupka, Cha, Loáiciga, Sharid, Nicholas, Sally Akevai Tenamu
Format: Preprint
Publié: 2025
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author Coto-Solano, Rolando
Li, Daisy
Ferraz, Manoela Teleginski
Sasse, Olivia
Krupka, Cha
Loáiciga, Sharid
Nicholas, Sally Akevai Tenamu
author_facet Coto-Solano, Rolando
Li, Daisy
Ferraz, Manoela Teleginski
Sasse, Olivia
Krupka, Cha
Loáiciga, Sharid
Nicholas, Sally Akevai Tenamu
contents We present experiments on diacritic restoration, a form of text normalization essential for natural language processing (NLP) tasks. Our study focuses on two extremely under-resourced languages: Bribri, a Chibchan language spoken in Costa Rica, and Cook Islands Māori, a Polynesian language spoken in the Cook Islands. Specifically, this paper: (i) compares algorithms for diacritics restoration in under-resourced languages, including tonal diacritics, (ii) examines the amount of data required to achieve target performance levels, (iii) contrasts results across varying resource conditions, and (iv) explores the related task of diacritic correction. We find that fine-tuned, character-level LLMs perform best, likely due to their ability to decompose complex characters into their UTF-8 byte representations. In contrast, massively multilingual models perform less effectively given our data constraints. Across all models, reliable performance begins to emerge with data budgets of around 10,000 words. Zero-shot approaches perform poorly in all cases. This study responds both to requests from the language communities and to broader NLP research questions concerning model performance and generalization in under-resourced contexts.
format Preprint
id arxiv_https___arxiv_org_abs_2512_19630
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Diacritic Restoration for Low-Resource Indigenous Languages: Case Study with Bribri and Cook Islands Māori
Coto-Solano, Rolando
Li, Daisy
Ferraz, Manoela Teleginski
Sasse, Olivia
Krupka, Cha
Loáiciga, Sharid
Nicholas, Sally Akevai Tenamu
Computation and Language
We present experiments on diacritic restoration, a form of text normalization essential for natural language processing (NLP) tasks. Our study focuses on two extremely under-resourced languages: Bribri, a Chibchan language spoken in Costa Rica, and Cook Islands Māori, a Polynesian language spoken in the Cook Islands. Specifically, this paper: (i) compares algorithms for diacritics restoration in under-resourced languages, including tonal diacritics, (ii) examines the amount of data required to achieve target performance levels, (iii) contrasts results across varying resource conditions, and (iv) explores the related task of diacritic correction. We find that fine-tuned, character-level LLMs perform best, likely due to their ability to decompose complex characters into their UTF-8 byte representations. In contrast, massively multilingual models perform less effectively given our data constraints. Across all models, reliable performance begins to emerge with data budgets of around 10,000 words. Zero-shot approaches perform poorly in all cases. This study responds both to requests from the language communities and to broader NLP research questions concerning model performance and generalization in under-resourced contexts.
title Diacritic Restoration for Low-Resource Indigenous Languages: Case Study with Bribri and Cook Islands Māori
topic Computation and Language
url https://arxiv.org/abs/2512.19630