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Binary Token-Level Classification with DeBERTa for All-Type MWE Identification: A Lightweight Approach with Linguistic Enhancement

Paper · 2026 · Diego Rossini and Lonneke van der Plas

Summary

The paper addresses the identification of multiword expressions (MWEs) of all types in English. Discontinuous cases such as look … up are especially hard, and the strongest earlier results came from very large LLMs. The authors fine-tune DeBERTa-v3-large to make three separate yes/no decisions for each token: whether it starts, ends, or lies inside an MWE. Spans are rebuilt from these predictions using thresholds tuned on development data. This design grows linearly with sentence length, unlike span enumeration.

The model also receives two syntactic signals as learned embeddings: NP-chunk membership and dependency-path distances. Dependency distances additionally filter out implausible discontinuous candidates. Class imbalance is handled through data augmentation.

On CoAM, the system reaches 69.8% F1, beating Qwen-72B by about 12 points with 165× fewer parameters. It also generalizes to STREUSLE, with 78.9% F1. The work shows that a compact, linguistically informed encoder can outperform LLMs on structured tasks of this kind, which is relevant when computing resources are limited.

Key points

  • Datasets: CoAM has 1,301 sentences (780 train / 521 test) and 867 MWEs with type labels (NOUN, VERB, MOD/CONN, CLAUSE, OTHER). STREUSLE v4.6 (UD v2.16) was remapped to CoAM-compatible types.
  • Linguistic features:
    • NP chunks from spaCy en_core_web_lg, encoded as 16-dim embeddings.
    • Dependency distances computed with NetworkX and capped at 5, encoded as 32-dim embeddings.
    • During reconstruction, discontinuous candidates are dropped if consecutive members are more than 4 dependency steps apart.
  • Augmentation depends on dataset size:
    • On CoAM, oversampling 30% of sentences containing MWEs worked best.
    • On the larger STREUSLE, lexical substitution worked better.
  • Discontinuous MWEs remain hard:
    • Recall roughly doubled compared with Qwen-72B (34.9% vs 17.1%).
    • F1 is still only 29.7%.
  • Release and limitations:
    • The model is available on Hugging Face (DiegoRossini/mwe-detection-deberta).
    • It predicts span boundaries but not MWE types.
    • It has been evaluated on English only.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

 Institutions

 Fields, topics and concepts

Cite

Cite as Diego Rossini and Lonneke van der Plas. 2026. Binary Token-Level Classification with DeBERTa for All-Type MWE Identification: A Lightweight Approach with Linguistic Enhancement. Findings of the Association for Computational Linguistics: EACL 2026.

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.18653/v1/2026.findings-eacl.135

@inproceedings{rossini2026binary,
  title = {{Binary Token-Level Classification with DeBERTa for All-Type MWE Identification: A Lightweight Approach with Linguistic Enhancement}},
  author = {Diego Rossini and Lonneke {van der Plas}},
  booktitle = {Findings of the Association for Computational Linguistics: EACL 2026},
  year = {2026},
  doi = {10.18653/v1/2026.findings-eacl.135},
  url = {https://doi.org/10.18653/v1/2026.findings-eacl.135}
}

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