Combining Unsupervised and Supervised Methods for PP Attachment Disambiguation

What it is about

The paper asks what to do when only a small treebank exists for prepositional phrase (PP) attachment. The data are German: 10,000 NEGRA sentences give the supervised examples, and about 5.5 million words of a computer magazine give raw co-occurrence counts. A cascade of count rules, with a noun factor of 5.47 or 5.97 to balance verb and noun counts, reaches 81.67% on the decidable cases (90.13% coverage) of a 4469-item test set. A back-off model trained on the small treebank reaches 73.98%. Ordering the two sources by reliability gives 80.98% on all 4469 items. With the roles swapped, the combination gives 71.95% against 68.29% for back-off alone.

For Mova

I1. en/src/parse.rs: add a cascade step for PP arcs (obl, nmod and advcl with a PP head). Each level is a count table with a threshold, and the level that decides is recorded. Measure coverage and accuracy on the EWT test PP attachments against the current perceptron choice. The tables come from EWT train only.
I2. Verb/noun bias factor: compute the ratio of overall verb-preposition to noun-preposition co-occurrence in the training data (the paper's noun factor) and scale the noun score before comparing. Measure on the two-fold check (en folds), not on the test set, and run twice to confirm identical output.
I3. Support-verb units as the first level: light-verb frames such as "take into account" or "make use of" with a PP, taken from the MWE list in languages/en/19-lexicon-mwe-register.md. Check the precision on EWT train before the rule is used. In the paper this level is very reliable (97 cases at 100% on German); the English count is unknown until measured.

The chapters are languages/en/22-phrases.md and 23-complementation.md (verb or noun choice for a PP complement). The code is en/src/parse.rs, with en/src/explain.rs for the per-level reason. The German figures do not carry over to English; the first English number must come from EWT test, with the two-fold check for decisions. Count tables are built from EWT train, which is CC BY-SA and may be used for training.

Institutions

🎓University of ZurichZurich ·

Switzerland44 works · 10,252 citations

Cite

Cite as Martin Volk. 2002. Combining Unsupervised and Supervised Methods for PP Attachment Disambiguation. COLING 2002: The 19th International Conference on Computational Linguistics.

The paper itself, not this card. BibTeX from the library's record of the work. DOI 10.3115/1072228.1072232

@inproceedings{volk2002combining,
  title = {{Combining Unsupervised and Supervised Methods for PP Attachment Disambiguation}},
  author = {Martin Volk},
  booktitle = {COLING 2002: The 19th International Conference on Computational Linguistics},
  year = {2002},
  doi = {10.3115/1072228.1072232},
  url = {https://doi.org/10.3115/1072228.1072232}
}

References

7 references, 3 of them with a card of ours. ↗ leads to the work, «find» searches for one we have no id for yet.

E. Brill and P. Resnik. 1994. A rule-based approach to prepositional phrase attachment disambiguation. In Proceedings of COLING, pages 1198–1204, Kyoto. ACL. find
M. Collins and J. Brooks. 1995. Prepositional phrase attachment through a backed-off model. In Proc. of the Third Workshop on Very Large Corpora. our card
D. Hindle and M. Rooth. 1993. Structural ambiguity and lexical relations. Computational Linguistics, 19(1):103–120. correct incorrect accuracy 2400 469 83.65% 1219 381 76.19% 3619 850 80.98% 4469 (of 4469) coverage: 100% threshold 0.020 0.109 number 97 6 269 845 2677 71 81 202 210 11 4469 coverage 2… our card
Adwait Ratnaparkhi. 1998. Statistical models for unsupervised prepositional phrase attachment. In Proceedings of COLING-ACL-98, Montreal. find
W. Skut, T. Brants, B. Krenn, and H. Uszkoreit. 1998. A linguistically interpreted corpus of German newspaper text. In Proc. of ESSLLI-98 Workshop on Recent Advances in Corpus Annotation, Saarbrücken. find
J. Stetina and M. Nagao. 1997. Corpus based PP attachment ambiguity resolution with a semantic dictionary. In J. Zhou and K. Church, editors, Proc. of the 5th Workshop on Very Large Corpora, Beijing and Hongkong. our card
Martin Volk. 2001. Exploiting the WWW as a corpus to resolve PP attachment ambiguities. In Proc. of Corpus Linguistics 2001, Lancaster, March. find

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📄 Combining Unsupervised and Supervised Methods for PP Attachment Disambiguation