2. 文献情報
BishanYang and Claire Cardie.
Extracting Opinion Expressions with semi- Markov Conditional Random Fields.
In Proceedings of the 2012 Joint Conference on EMNLP and CoNLL, pp. 1335-1345. (2012)
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※本スライド中の数式,図表はすべて文献より引用
6. 背景| 意見抽出
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The International Committee of the Red Cross, [as usual][ESE], [has refused to make any statements][DSE].
•
The Chief Minister [said][DSE]that [the demon they have reared will eat up their own vitals][ESE].
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13. Semi-CRFs
•
正しいsegmentationは抽出すべきentities とそうでないsegmentの列で定義される
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(The,NONE),(Chief,NONE),(Minister,NONE), (said,DSE),(that,NONE),(the demon they have reared will eat up their own vitals,ESE),(.,NONE)
例
18. 提案手法| segmentation
•
訓練データ各文に対して正しい segmentationを得る
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(The ChiefMinister,NONE),(said,DSE),
(that,NONE),(the demon they have reared will eat up their own vitals,ESE),(.,NONE)
例
31. 実験| 評価尺度
•
precision, recall, F-measure
–
意見表現の境界線は明確ではない
Binary-Overlap (Brecket al. 2007)
Proportional-Overlap(Johansson and Moschitti2010)
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Eric Breck, YejinChoi, and Claire Cardie. Identifying expressions of opinion in context. IJCAI ’07. (2007)
Richard Johansson and Alessandro Moschitti. Syntactic and semantic structure for opinion expression detection. In Proceedings of CoNLL’10. (2010)