Using Hedge Detection to Improve Committed Belief Tagging
What it is about
The paper adds hedge features to a committed-belief tagger. The tagger marks each proposition head as committed belief (CB), non-committed belief (NCB), reported belief (ROB) or non-belief (NA: desire, intention, question). Hedges are found from a 117-term dictionary in two ways: plain lemma lookup, or hand rules over POS and dependencies that separate hedge from non-hedge uses. For example, about as a preposition is not a hedge; likely as amod of a noun is not; assume, tend and appear are hedges only with a clausal complement; sure and completely are hedges only under negation; supposed to and should have are not. Features for the word itself, its parent, children, siblings and ancestors, plus a sentence flag, go into an SVM. On the DEFT forum corpus (5-fold CV), rule-based hedge features raise NCB F1 from 23.7 to 30.4 and ROB from 23.3 to 27.4; overall F1 rises only from 67.5 to 68.1, because those classes are rare.
Ideas
- I1. Give each Mova frame a commitment value next to
negandcondinprag::frames(prag/src/frames.rs): committed, non-committed (a hedge or modal governs the predicate), reported (inside thequoteof a Say frame whose speaker is not the narrator), or not a belief (wish, intention, question). Most of the information is already present: Say frames,cond, modals infeats. - I2. Let the student weigh by it. In
world/src/knowledge.rsa remembered frame that is non-committed («maybe the wolf ate it») or reported («the fox said the cheese was poisoned») should support an option less than a committed narrator fact. Measure course test counts and theworld knowledge diagnosestep-5 share (right option outscored). - I3. Hedge rules that look at the parent and siblings, not only the token: a hedge counts for a proposition when it is the head's child (
advmod) or the head's governing verb («I think [p]»). The same tree position decides which frame inherits non-commitment in I1. Test it on frame bench lines with think, maybe or seem. - I4. Negation flips boosters into hedges («not sure», «isn't completely true»). Reuse
infer::negatedfor this one rule in the hedge slot.
For Mova
32. Politeness and hedging §8 (epistemic modality and evidentiality), 33. Implicature and presupposition (speaker commitment); prag/src/frames.rs, prag/src/feats.rs, world/src/knowledge.rs; measures: frame bench F1 unchanged (no regression), course test counts, the diagnose breakdown.
Cite
@inproceedings{ulinski2018using,
title = {{Using Hedge Detection to Improve Committed Belief Tagging}},
author = {Ulinski, Morgan and Benjamin, Seth and Hirschberg, Julia},
booktitle = {Proceedings of the Workshop on Computational Semantics beyond Events and Roles},
year = {2018},
doi = {10.18653/v1/w18-1301},
url = {https://doi.org/10.18653/v1/w18-1301}
}References
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