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RST Discourse Corpus

RST Discourse Corpus. Lynn Carlson Daniel Marcu Mary Ellen Okurowski. Theory and Phenomena Annotated. Framework for annotation: Rhetorical Structure Theory (Mann and Thompson, 1988) Discourse structure of text represented as tree defined as follows:

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RST Discourse Corpus

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  1. RST Discourse Corpus Lynn Carlson Daniel Marcu Mary Ellen Okurowski

  2. Theory and Phenomena Annotated • Framework for annotation: • Rhetorical Structure Theory (Mann and Thompson, 1988) • Discourse structure of text represented as tree defined as follows: • Leaves: text fragments (mainly clauses) that represent elementary discourse units • Internal nodes of tree = contiguous text spans • Each node characterized by nuclearity: nucleus = more essential unit; satellite = supporting unit • Each node characterized by rhetorical relation that holds between two or more non-overlapping, adjacent spans

  3. Sample Text with EDUs: wsj_1111 [Still, analysts don’t expect the buy-back to significantly affect per-share earnings in the short term.]16 [“The impact won’t be that great,”]17 [said Graeme Lidgerwood of First Boston Corp.]18 [This is in part because of the effect]19 [of having to average the number of shares outstanding,]20 [she said.]21 [In addition,]22 [Mrs. Lidgerwood said,]23 [Norfolk is likely to draw down its cash initially]24 [to finance the purchases]25 [and thus forfeit some interest income.]26 wsj_1111

  4. 22-25 example elaboration-additional (16) 17-26 17-21 explanation-argumentative 22-26 consequence-s 19-21 (26) 17-18 attribution attribution same-unit 19-20 (17) (18) (21) 22-23 24-25 * + purpose (20) (19) (22) (23) (24) (25) +attribution embedded *elaboration-object-attribute-embedded Sample Discourse Tree: wsj_1111

  5. Nature of Rhetorical Relations • Attribution: attribution, attribution-negative • Background: background, circumstance • Cause: cause, result, consequence • Comparison: comparison, preference, analogy, proportion • Condition: condition, hypothetical, contingency, otherwise • Contrast: contrast, concession, antithesis • Elaboration: elaboration-additional, elaboration-general-specific • Enablement: purpose, enablement • Evaluation: evaluation, interpretation, conclusion, comment • Explanation: evidence, explanation-argumentative, reason • Joint: list, disjunction • Manner-Means: manner, means • Topic-Comment: problem-solution, question-answer, topic-comment.. • Summary: summary, restatement • Temporal: temporal-before, temporal-after, temporal-same-time.. • Topic Change: topic-shift, topic-drift

  6. Corpus and Annotation Details • 385 WSJ articles from Penn Treebank, representing over 176,000 words of text. ~14% were double-tagged. • Document length: 31 to 2124 words; average of 458.14 words • Average # EDUs per document: 56.59. • Average # words per EDU: 8.1. • Nature of articles: general news, financial, business, cultural reviews, editorials • Intended users: developers of automatic text processing systems

  7. Inter-Annotator Agreement

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