Closing the Gap: Robust Multilingual Coreference Resolution with DAgger

Thomas Morton, Alex Warstadt


Abstract
We present DAggerCoref, our submission to the CRAC 2026 Shared Task on Multilingual Coreference Resolution. DAggerCoref is a three-stage cascade built on XLM-RoBERTa-large: a gap classifier for zero pronoun detection, a mention head classifier, and a coarse-to-fine antecedent scorer. Our central contribution is applying DAgger (Ross et al., 2011) to coreference resolution: after training the antecedent scorer on gold mentions, we fine-tune on a 50/50 mix of gold and pipeline-predicted mentions, closing the train/test distribution mismatch and improving development set macro CoNLL F1 by 1.10 points. We also introduce Otsu adaptive thresholding for zero pronoun detection, which matches gold-tuned per-dataset thresholds without requiring any gold supervision. Our system achieves a macro CoNLL F1 of 67.56 on the official test set across 27 datasets and 19 languages
Anthology ID:
2026.codi-1.28
Volume:
Proceedings of the 2nd Joint Workshop on Computational Approaches to Discourse, Context and Document-Level Inferences and Computational Models of Reference, Anaphora and Coreference (CODI-CRAC 2026)
Month:
July
Year:
2026
Address:
San Diego, California, USA
Editors:
Chloé Braud, Christian Hardmeier, Maciej Ogrodniczuk, Sharid Loaiciga, Amir Zeldes, Michal Novák, Chuyuan Li, Michael Strube, Junyi Jessy Li
Venues:
CODI | CRAC | WS
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Publisher:
Association for Computational Linguistics
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Pages:
217–221
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URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.codi-1.28/
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Cite (ACL):
Thomas Morton and Alex Warstadt. 2026. Closing the Gap: Robust Multilingual Coreference Resolution with DAgger. In Proceedings of the 2nd Joint Workshop on Computational Approaches to Discourse, Context and Document-Level Inferences and Computational Models of Reference, Anaphora and Coreference (CODI-CRAC 2026), pages 217–221, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
Closing the Gap: Robust Multilingual Coreference Resolution with DAgger (Morton & Warstadt, CODI-CRAC 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.codi-1.28.pdf
Supplementarymaterial:
 2026.codi-1.28.SupplementaryMaterial.zip