A Global Relaxation Labeling Approach to Coreference Resolution
Summary
The paper addresses coreference resolution, which is grouping the mentions in a text that refer to the same entity. Typical systems first score mention pairs or groups and then build chains in a separate step. Errors from the context-poor first step carry over into the second. The authors merge both steps into one global procedure. Each mention becomes a vertex in a graph, and the edge weights are sums of weighted constraints. Constraints are learned automatically from a training corpus using pairwise feature functions, with separate models depending on anaphor type. The partitioning of vertices into entities is then found iteratively by relaxation labeling. Each vertex holds a probability distribution over possible partitions, which is updated from the support of earlier mentions. This keeps the result consistent without explicit transitivity constraints. Pruning, reordering, and an informed initial state further improve results. On the ACE-phase02 corpus, the method beats decision-tree baselines, an ILP chain-formation baseline, and the best published systems using the same data and metrics. It also scales better than ILP and makes it easy to add knowledge from other sources as constraints.
Key points
- Best configuration (Relax with pruning and reordering) reaches a global CEAF F1 of 69.7 and a B3 F1 of 74.9 on ACE-phase02 (bnews, npaper, nwire).
- Prior results on the same data: MaxEnt+ILP (Denis, 2007) scored 66.2 CEAF / 72.7 B3, and Rankers scored 67.0 CEAF / 72.7 B3.
- Hill Climbing feature selection, optimized for CEAF, raised the decision-tree baseline by 5.1 CEAF and 5.3 B3 points.
- The ILP baseline needs a cubic number of triangular constraints, so it could only handle documents with fewer than 200 mentions.
- Relaxation stops when label probabilities change by less than 0.001 or after 2000 iterations. An informed initial state outperformed a random one (averaged over 3 runs).
Cited by
- Data-driven Multilingual Coreference Resolution using Resolver Stacking
- Poly-co: a multilayer perceptron approach for coreference detection
- Multigraph Clustering for Unsupervised Coreference Resolution
- RelaxCor: A Global Relaxation Labeling Approach to Coreference Resolution
- RelaxCor Participation in CoNLL Shared Task on Coreference Resolution
- A Constraint-Based Hypergraph Partitioning Approach to Coreference Resolution
Cite
@inproceedings{sapena2010global,
title = {{A Global Relaxation Labeling Approach to Coreference Resolution}},
author = {Sapena, Emili and Padró, Lluís and Turmo, Jordi},
booktitle = {Coling 2010: Posters},
year = {2010},
url = {https://aclanthology.org/C10-2125/}
}References
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