Hedge Detection and Scope Finding by Sequence Labeling with Procedural Feature Selection
Paper · 2010 · Shaodian Zhang, Hai Zhao, Guodong Zhou et al.
Summary
The paper describes a system built for the CoNLL-2010 shared task. The task has two parts: detecting speculative language (hedges) and resolving the scope of each hedge cue. Data came from the BioScope corpus (biomedical abstracts and full texts) and from Wikipedia "weasel" annotations. Both tasks are cast as token-level sequence labeling with Maximum Entropy Markov Models.
- Detection: words are tagged as cue or non-cue. A sentence counts as uncertain if any word carries a cue tag.
- Scope finding: the system first labels cues, then labels scope boundaries.
- Sentences with several cues: each one is duplicated once per cue. An "Indicator" feature marks words already covered by earlier scopes, which discourages crossing scopes.
- Feature selection: about 200 templates per task, many built from dependency-tree relations, were reduced by greedy selection. This was run separately for each sub-task and for each corpus, because the expert annotation and the crowd annotation behave differently.
In the closed track, detection F-scores were 0.8363 on BioScope and 0.5618 on Wikipedia, the latter ranking near the top. Scope F was about 0.44. Further feature selection after the deadline gave better results.
Key points
- Hedge detection reached F 0.8363 on BioScope and F 0.5618 on Wikipedia. Scope resolution scored F 0.4425 (closed) and 0.4441 (open).
- About a quarter of hedged sentences contain more than one cue. For example, the BioScope abstracts have 498 multi-hedge sentences out of 11,871.
- Scope labels are Begin, Middle, End and out-of-scope, but only Begin and End count in evaluation.
- Many features come from dependency parses produced by the Zhao et al. (2009a) parser:
- paths between words and their shared and non-shared parts;
- children sets;
- support verbs, nouns and prepositions.
- Strings collected along paths or children are joined in one of three ways: in order (seq), as a sorted set (bag), or with adjacent repeats removed (noDup).
- The authors blame the modest scope results on two things: feature selection that was not run to completion, and mixing abstracts with full texts in training when the test set held only full texts.
Interesting ideas
- I1. Optimizing a sentence-level decision and optimizing a token-level intermediate step can call for different feature sets, so the authors tune each step separately rather than reusing one model.
- I2. Copying a multi-cue sentence once per cue turns one hard joint labeling problem into several single-target problems, whose results are then merged.
- I3. A soft feature marking tokens already inside earlier scopes pushes later predictions to respect tree-like nesting without imposing a hard constraint.
- I4. Features are built from dependency paths and grouped as ordered, set-like or de-duplicated sequences, which captures words that are far apart in the sentence but close in the tree.
- I5. Expert-annotated and crowd-annotated corpora get separate feature selection, and training on a mixture of genres hurt performance on full texts.
For Mova
How these ideas could serve Mova, our small open language model — its files, stages and tests:
- I1 (learn): when a component serves both as a final output and as an input to later stages, evaluate and tune it against each use separately.
- I2 (frames): role labeling for sentences with several predicates could run one pass per predicate, which keeps frames from bleeding into each other.
- I3 (frames): when assigning spans for negation or modality, earlier decisions could be passed on as features, so that partially overlapping scopes become unlikely and any remaining overlap can be flagged as an explainable error.
- I4 (frames): speculation and modality detectors could read their evidence directly from the UD tree, which keeps the decision traceable to specific arcs.
- I5 (learn): track which source and genre each piece of silver or treebank data comes from, and evaluate per domain before pooling.
Institutions
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksArts and Humanities · 16,039 worksLanguage and Linguistics · 15,891 works
Cite
Cite as Shaodian Zhang, Hai Zhao, Guodong Zhou and Bao-Liang Lu. 2010. Hedge Detection and Scope Finding by Sequence Labeling with Procedural Feature Selection. Proceedings of the Fourteenth Conference on Computational Natural Language Learning – Shared Task.
@inproceedings{zhang2010hedge,
title = {{Hedge Detection and Scope Finding by Sequence Labeling with Procedural Feature Selection}},
author = {Shaodian Zhang, Hai Zhao, Guodong Zhou and Bao-Liang Lu},
booktitle = {Proceedings of the Fourteenth Conference on Computational Natural Language Learning – Shared Task},
year = {2010},
url = {https://aclanthology.org/W10-3013/}
}References
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