Understanding Mention Detector-Linker Interaction in Neural Coreference Resolution
Summary
Wu and Gardner analyze why strong neural coreference systems still fall short of human performance. They study SpanBERT + c2f-coref, the leading member of the end-to-end model family, and separate its two parts: a mention detector that proposes candidate spans and a linker that chooses antecedents. Using the CoNLL-2012 and PreCo development sets, they build oracle detectors that add missing gold mentions, remove spurious ones, or do both. They also build an oracle linker that always picks the correct antecedent. Errors are categorized using the Kummerfeld and Klein (2013) taxonomy. Detectors are usually designed to favor recall, but the experiments show that precision matters more. Noisy candidates make the linker less confident even about correct links. However, a precise detector is hard to build because the detector cannot reliably judge anaphoricity. With the original candidates, an ideal linker would score almost perfectly, and most remaining linker mistakes involve pronouns. The authors suggest dedicated anaphoricity modules and better contextual reasoning as next steps.
Key points
- Baseline: The SpanBERT-large + c2f-coref system (L=30, Ξ»=0.4, K=50, no speaker or genre metadata) reaches 79.17 coreference F1 on CoNLL-12 and 85.04 on PreCo. Its anaphoric-mention recall exceeds 96%, but precision is only 28.37% (CoNLL-12) and 39.23% (PreCo).
- Precision vs. recall oracles (CoNLL-12): The comparison baseline is 78.28 F1.
- Giving the linker perfect anaphoric precision raises F1 to 86.02 post-hoc and 89.98 with re-training.
- Perfect recall yields only about 79.4β79.7 F1.
- Increasing max span width L or Ξ» does not improve on the original setting.
- Anaphoricity: A classifier trained explicitly to separate anaphoric mentions from singletons has a confusion index of 0.81, where 1 corresponds to random guessing. When the same text appears as both types within a document, the index rises to 0.997.
- Linker ceiling: An oracle linker using the original candidates scores 97.07 F1 (CoNLL-12) and 98.69 (PreCo). Restricting it to coarse-pruned antecedents still gives 96.61 and 98.65.
- Remaining errors: The authors manually inspected 150 conflated-entity errors on CoNLL-12, assuming a perfect detector. Of these, 109 involve pronouns, most often a pronoun linked to the wrong nominal (43 cases).
Cited by
- Annotating Mentions Alone Enables Efficient Domain Adaptation for Coreference Resolution
- Are Large Language Models Robust Coreference Resolvers?
- Seq2seq is All You Need for Coreference Resolution
Cite
@inproceedings{wu2021understanding,
title = {{Understanding Mention Detector-Linker Interaction in Neural Coreference Resolution}},
author = {Wu, Zhaofeng and Gardner, Matt},
booktitle = {Proceedings of the Fourth Workshop on Computational Models of Reference, Anaphora and Coreference},
year = {2021},
doi = {10.18653/v1/2021.crac-1.16},
eprint = {2009.09363},
archivePrefix = {arXiv},
url = {https://doi.org/10.18653/v1/2021.crac-1.16}
}References
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