Importance of Pronominal Anaphora Resolution in Question Answering Systems
Summary
The paper asks whether open-domain Question Answering systems lose useful information when they ignore pronouns in documents. The authors first measure how often pronouns occur in ten text collections used in TREC-8 QA and in IR testing. Pronoun use is heavy in newswire and much lower in technical abstracts, where "it/its" dominates. They then build a full pipeline to test the effect. A Salton-style IR engine (idf weighting, Porter stemming, cosine similarity) retrieves documents. The SUPAR parser, which uses Slot Unification Grammar, resolves pronominal anaphora in both queries and documents without semantic resources. A sentence-extraction QA module ranks sentences, scoring a resolved pronoun with the weight of its antecedent. Tests on the LAT corpus compare the system with and without resolution. Resolution raises the share of correct answers from 29.03% to 54.84%. The gain is largest when query terms appear only as pronouns in the answer sentence. The authors conclude that pronoun resolution should be a standard part of open-domain QA, and that it is essential for noun-phrase extraction systems.
Key points
- The pronominal reference ratio ranges from 55.20% in LAT down to 9.05% in CRANFIELD. News collections (LAT, FBIS, TIME, FT) lie between 35.96% and 55.20% and contain many third-person pronouns.
- SUPAR combines a POS tagger, partial parsing, statistical knowledge, c-command and morphological agreement constraints, and preference heuristics. It does not use WordNet or other semantic knowledge.
- Evaluation used 93 questions, the subset of 150 for which the IR step found the relevant document. These were split into groups A, B and C according to how pronouns relate to the answer.
- Overall, target sentences in the system's output rose from 41.94% to 54.84%, and correct answers from 29.03% to 54.84%. For group C, target sentences rose from 29.03% to 67.74%.
- On a rebalanced set of 83 questions, matched to LAT's pronoun ratio, the gains were similar: +10.84 points for target sentences and +22.89 points for correct answers.
Cited by
- Contrastive Representation Learning for Cross-Document Coreference Resolution of Events and Entities
- A Public Reference Implementation of the RAP Anaphora Resolution Algorithm
Cite
@inproceedings{vicedo2000importance,
title = {{Importance of Pronominal Anaphora Resolution in Question Answering Systems}},
author = {Vicedo, José L. and Ferrández, Antonio},
booktitle = {Proceedings of the 38th Annual Meeting of the Association for Computational Linguistics},
year = {2000},
doi = {10.3115/1075218.1075288},
url = {https://doi.org/10.3115/1075218.1075288}
}References
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