Robust Language Identification for Romansh Varieties
Paper · 2026 · Charlotte Model, Sina Ahmadi and Jannis Vamvas
Summary
Romansh, spoken by roughly 40,000 people in the Swiss canton of Grisons, exists as five regional idioms (Sursilvan, Sutsilvan, Surmiran, Puter, Vallader) plus the supra-regional written standard Rumantsch Grischun (RG). Existing language identification tools either skip Romansh or treat it as one language. Current dictionary and spell-checking services also make users pick the idiom manually. The authors build what they describe as the first documented LID system that tells all six varieties apart. They combine five sources: the Pledari Grond dictionary, La Quotidiana news, RTR broadcast transcripts, RTR Telesguard newsroom notes and Mediomatix textbooks. These are cleaned, deduplicated and optionally masked for named entities using a SwissBERT-based NER model. They then compare linear scikit-learn classifiers on TF–IDF character and word n-grams. A tuned linear SVM performs best, averaging about 97% accuracy on in-domain test sets, though results drop clearly on out-of-domain data. The released classifier can route texts to idiom-specific tools such as spell checkers or machine translation. It also offers a template for other low-resource regional varieties.
Key points
- Data and splits: The corpus has 487,172 samples, about 12.4M tokens. Training uses PG, LQ, RTR and TB. Evaluation uses four test sets: three in-domain (LQ, RTR, TB) and one out-of-domain (TG newsroom notes).
- Model comparison: The best SVM uses ℓ1 penalty, character 1–4-grams and word unigrams, reaching 97.1 macro F1 on the dev set. Logistic Regression reaches 96.8. Before tuning, the baselines scored only about 69–77 macro F1.
- Scores across test sets: Macro F1 reaches up to 98 on balanced in-domain data but falls to 69.1 on out-of-domain test-d.
- Named-entity masking: Masking has almost no effect on scores (≤0.1 F1 on most sets, 0.7 at most). This suggests the model relies on linguistic cues rather than memorised proper nouns.
- Discriminative features: Character n-grams carry the most signal. Two of the top features are artefacts that may not transfer to ordinary text:
- underdotted stress markers in Puter/Vallader dictionary entries;
- whitespace for RG, caused by class imbalance (≈171K RG samples versus 44K–86K for each other idiom).
- Availability: The code is at github.com/ZurichNLP/romansh-lid.
Institutions
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 18,614 worksArtificial Intelligence · 17,965 worksArts and Humanities · 17,450 worksLanguage and Linguistics · 17,296 works
🧭 Topics 1Research subjects and languages the work is about.Idioms & multiword expressions · 222 works
Cite
Cite as Charlotte Model, Sina Ahmadi and Jannis Vamvas. 2026. Robust Language Identification for Romansh Varieties. Proceedings of the 11th Edition of the Swiss Text Analytics Conference.
@inproceedings{model2026robust,
title = {{Robust Language Identification for Romansh Varieties}},
author = {Charlotte Model, Sina Ahmadi and Jannis Vamvas},
booktitle = {Proceedings of the 11th Edition of the Swiss Text Analytics Conference},
year = {2026},
url = {https://aclanthology.org/2026.swisstext-1.9/}
}References
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