FOCUS: Effective Embedding Initialization for Monolingual Specialization of Multilingual Models
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Using model weights pretrained on a highresource language as a warm start can reduce the need for data and compute to obtain highquality language models for other, especially low-resource, languages.However, if we want to use a new tokenizer specialized for the target language, we cannot transfer the source model's embedding matrix.In this paper, we propose FOCUS -Fast Overlapping Token Combinations Using Sparsemax, a novel embedding initialization method that initializes the embedding matrix effectively for a new tokenizer based on information in the source model's embedding matrix.FOCUS represents newly added tokens as combinations of tokens in the overlap of the source and target vocabularies.The overlapping tokens are selected based on semantic similarity in an auxiliary static token embedding space.We focus our study on using the multilingual XLM-R as a source model and empirically show that FOCUS outperforms random initialization and previous work in language modeling and on a range of downstream tasks (NLI, QA, and NER).We publish our checkpoints and code on GitHub. 1
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Cited by
Sorted by citations
Kiulian, A., Polishko, A., Khandoga, M., Kostiuk, Y., Gabrielli, G., Gagała, Ł., Zaraket, F., Abu Obaida, Q., Garud, H., Wing Yee Mak, W., et al. (2025) · Proceedings of the Fourth Ukrainian Natural Language Processing Workshop (UNLP 2025) · doi:10.18653/v1/2025.unlp-1.1 · Cited by 2 · see citing works
Writing-System-Level Tokenizer Adaptation for Byte-Level BPE
Didenko, B. (2026) · arXiv · doi:10.48550/arxiv.2608.00582
“Methods range from sub-token averaging (Kim et al., 2024) and overlap-based transfer (Dobler & de Melo, 2023; Remy et al., 2023; Kiulian et al., 2025) to model-aware approaches such as MATT (Haltiuk & Smywinski-Pohl, 2025).”
- Authors
- Dobler, K., & de Melo, G.
- Affiliations
- Hasso Plattner Institute (DE)
- Venue
- Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing
- Published
- 2023
- Pages
- 13440-13454
- OpenAlex
- W4389524262
- Cited by
- 8
- References
- 6
- Citations by year
- 2026: 3 · 2025: 3 · 2024: 1 · 2023: 1
- FWCI
- 1.42
- Type
- conference paper
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- cc-by
- Locations
- Conference on Empirical Methods in Natural Language Processing (EMNLP) (publishedVersion, cc-by)
- arXiv (Cornell University) (submittedVersion)
- arXiv (Cornell University)
- Funders
- Bundesministerium für Bildung und Forschung (01IS22092)
- Topics
- Physical Sciences › Computer Science › Artificial Intelligence › Topic Modeling
- Physical Sciences › Computer Science › Artificial Intelligence › Natural Language Processing Techniques
- Physical Sciences › Computer Science › Artificial Intelligence › Domain Adaptation and Few-Shot Learning
- Keywords
- embedding initialization, multilingual language models, low-resource languages, XLM-R, warm start, semantic similarity, language modeling, natural language inference, question answering, named entity recognition
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