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Token Titans at BEA 2026 Shared Task 1: Multilingual Lexical Complexity Prediction via Fine-Tuned XLM-RoBERTa with Ensemble Decoding

Paper · 2026 · Anubhab Parashar and Sandeep Mathias

Summary

This system paper presents the authors' entry in the BEA 2026 shared task that targets vocabulary difficulty prediction. The task asks systems to estimate how hard words are for English learners whose L1 is Spanish, German or Chinese. Each instance pairs an L1 word and its sentence context with an English clue and an English target word. The authors fine-tune a separate XLM-RoBERTa Large regressor for each language, using a linear head on [CLS]. All four fields are merged into one string joined by </s> separators. GLMM labels are z-score normalized per language. Two runs per language vary the learning rate, scheduler and seed, and German alone gets a weighted ensemble. The headline figures, RMSE 1.170 and Pearson 0.812, come from Spanish only, where the system beats the xlm-roberta-base baseline. For German and Chinese, the baseline is better on RMSE. The authors blame unstable fine-tuning of a large model on small data, with a small effective batch, low learning rates and no dropout on the head. The paper shows that a single hyperparameter setup does not transfer across typologically different languages.

Key points

  • Input format: L1_word </s> L1_context </s> en_clue </s> en_target. For Chinese, whitespace is collapsed before tokenization. Predictions are denormalized and clipped to [0.05, 5.0].
  • Training setup:
    • AdamW, fp16, effective batch size 8, 5 epochs, 500 warmup steps.
    • Learning rates of 1e-5 to 1.2e-5.
    • Linear or cosine schedulers, seeds 42 and 1337.
    • No external data or lexical resources.
  • Spanish results:
    • Run 1 reached RMSE 1.170 and r 0.812, against a baseline of 1.257 and 0.765.
    • Run 2 collapsed to r 0.043.
  • German results: the 0.6/0.4 ensemble only matched Run 2, at RMSE 1.569 and r 0.772. The baseline scored 1.258 and 0.773.
  • Chinese results:
    • The baseline's RMSE of 1.140 beat both runs, which scored 1.382 and 1.436.
    • Run 2 had the best Pearson, 0.777 against the baseline's 0.753.

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

Also on the byline: Presidency University.

 Fields, topics and concepts

Cite

Cite as Anubhab Parashar and Sandeep Mathias. 2026. Token Titans at BEA 2026 Shared Task 1: Multilingual Lexical Complexity Prediction via Fine-Tuned XLM-RoBERTa with Ensemble Decoding. Proceedings of the 21st Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2026).

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.18653/v1/2026.bea-1.80

@inproceedings{parashar2026token,
  title = {{Token Titans at BEA 2026 Shared Task 1: Multilingual Lexical Complexity Prediction via Fine-Tuned XLM-RoBERTa with Ensemble Decoding}},
  author = {Anubhab Parashar and Sandeep Mathias},
  booktitle = {Proceedings of the 21st Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2026)},
  year = {2026},
  doi = {10.18653/v1/2026.bea-1.80},
  url = {https://doi.org/10.18653/v1/2026.bea-1.80}
}

References

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