The Geometry of Low-Resource Language Representations

Francois Meyer, Jan Buys


Abstract
The performance gap between low- and high-resource languages in LLMs is widely known, but it remains unclear which internal model factors drive these disparities. In this paper, we characterise this gap through the lens of representational geometry. Comparing the geometric properties of hidden representations across 30 languages reveals that LLM geometry is systematically related to language data availability. The most consistent effect is in final layers, where low-resource languages exhibit representational degeneration. To counter this, we investigate the effectiveness of regularisation terms to penalise degeneration during continued pretraining (CPT). Experiments monolingually adapting 9 base LLMs to 10 African languages show that geometric regularisation successfully reduces representational degeneration during CPT. For larger models, cosine similarity-based regularisation marginally improves performance over vanilla CPT, with more consistent gains on the most challenging tasks. We establish that the representational geometry of low- and high-resource languages in LLMs is measurably distinct, and that targeted geometric intervention is a viable strategy for improving CPT for low-resource languages.
Anthology ID:
2026.emnlp-main.2097
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
47748–47763
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2097/
DOI:
Bibkey:
Cite (ACL):
Francois Meyer and Jan Buys. 2026. The Geometry of Low-Resource Language Representations. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 47748–47763, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
The Geometry of Low-Resource Language Representations (Meyer & Buys, EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2097.pdf