Ambirig at SemEval-2026 Task 5: Distributional Ordinal Modelling for Ambiguous Word Senses in Narrative Contexts
Paper · 2026 · Soumyajit Roy
Summary
SemEval-2026 Task 5 asks systems to score how plausible a given sense of a homonym is within a short English story, on a 1–5 scale. Human raters often disagree on these scores. The author frames the task as predicting an ordinal distribution over ratings rather than a single number. The system is a GlossBERT-style cross-encoder built on DeBERTa-v3-base. Its input pairs the sense definition and an example usage with the story, and the target word is wrapped in quotes. A softmax head outputs probabilities for the five ratings. It is trained against the empirical annotator vote distribution using a squared Earth Mover's Distance (EMD) loss over CDFs. With only 2,280 training items, the model reached Spearman 0.593 and accuracy 0.730 on the development set, and 0.49 and 66.6% on the blind test set. It outperformed MSE regression, contrastive, CORAL and entropy-based variants. TAPT, NLI initialisation and complementarity constraints all lowered results. The study suggests that, for truly ambiguous data, a loss that preserves disagreement matters more than model scale or auxiliary training.
Key points
- Data: 2,280 training and 588 development instances. Each instance has a three-sentence precontext, an ambiguous sentence, an optional ending and a candidate sense.
- Setup: microsoft/deberta-v3-base, AdamW with lr 1.5e-5, batch 8, 5 epochs and 300-token inputs. DeBERTa-Large (435M) overfit.
- Development-set results:
- EMD: ρ = 0.593, Acc = 0.730.
- Entropy loss: 0.586.
- CORAL: 0.518.
- MSE regression: ≈0.00, because it collapsed to predicting around 3.4–3.5.
- Failed additions:
- Complementarity constraint: ρ = 0.135.
- TAPT: ρ = 0.501.
- NLI initialisation (cross-encoder/nli-deberta-v3-base): ρ = 0.447.
- Adding a pairwise ranking loss brought no gain.
- On high-variance items, EMD kept a lower MAE than a Cross-Entropy baseline. Code is announced at github.com/roysammy/ambirig.
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.Word sense disambiguation · 87 works
Cite
Cite as Soumyajit Roy. 2026. Ambirig at SemEval-2026 Task 5: Distributional Ordinal Modelling for Ambiguous Word Senses in Narrative Contexts. Proceedings of the 20th International Workshop on Semantic Evaluation (2026).
@inproceedings{roy2026ambirig,
title = {{Ambirig at SemEval-2026 Task 5: Distributional Ordinal Modelling for Ambiguous Word Senses in Narrative Contexts}},
author = {Soumyajit Roy},
booktitle = {Proceedings of the 20th International Workshop on Semantic Evaluation (2026)},
year = {2026},
doi = {10.18653/v1/2026.semeval-1.84},
url = {https://doi.org/10.18653/v1/2026.semeval-1.84}
}References
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