UBIU: A Language-Independent System for Coreference Resolution
Summary
The paper tackles coreference resolution for many languages, where machine-learned systems usually exist for only a few languages or a fixed set. The authors developed UBIU as an entry in SemEval-2010 Task 1, the shared task on resolving coreference across many languages. It pairs memory-based learning in TiMBL with a mention-pair feature set adapted from Rahman and Ng (2009). The features rely only on standard annotation layers (POS, morphology, dependency relations, named entities), and a feature gets a null value when a language lacks that layer.
The only language-specific component is a small set of regular expressions that find markable heads. A markable's full extent is reconstructed afterwards from dependency subtrees. In postprocessing, each mention keeps its highest-confidence antecedent, and pronouns are always forced to receive one.
An ablation shows that accurate mention boundaries matter far more than gold linguistic annotation. This suggests the system can run on automatically parsed data with little loss, which is useful for less-resourced languages.
Key points
- Shared task and scale: evaluated on SemEval-2010 Task 1 across Catalan, Dutch, English, German, Italian and Spanish. Development took about 4 months, and adapting the head-finding module to a new language needs roughly 1 person-hour.
- Classifier settings: TiMBL parameters were tuned jointly for the best average across all languages rather than per language. The chosen setting is k=3 with Overlap distance and gain ratio weighting.
- Ablation on development data (Catalan, English, German, Spanish):
- Gold markables raise mention identification by about 20+ F1 points (e.g., English 96.1 vs. 72.1).
- Swapping gold linguistic annotation for automatic annotation changes the scores very little.
- Official results (regular setting):
- English is strongest (CEAF 53.6, B³ 58.7).
- Dutch is weakest (CEAF 17.0), partly because its named-entity markables exclude determiners that the dependency subtree includes.
- Postprocessing fallback for pronouns: when no candidate is classified as coreferent, the system picks the closest subject. If that fails, it takes the candidate TiMBL rejected with the lowest confidence.
Cited by
- Neural Coreference Resolution for Arabic
- Singletons and Coreference Resolution Evaluation
- IMS HotCoref DE: A Data-driven Co-reference Resolver for German
Cite
@inproceedings{zhekova2010ubiu,
title = {{UBIU: A Language-Independent System for Coreference Resolution}},
author = {Zhekova, Desislava and Kübler, Sandra},
booktitle = {Proceedings of the 5th International Workshop on Semantic Evaluation},
year = {2010},
url = {https://aclanthology.org/S10-1019/}
}References
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