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Doporučená literatura
- Rodger Kibble, Richard Power. 2004. Optimizing referential coherence in text generation. Computational linguistics, Vol. 30, No. 4, pp. 401-416. pdf
Abstract
This article describes an implemented system which uses centering theory for planning of coherent texts and choice of referring expressions. We argue that text and sentence planning need to be driven in part by the goal of maintaining referential continuity and thereby facilitating pronoun resolution: Obtaining a favorable ordering of clauses, and of arguments within clauses, is likely to increase opportunities for nonambiguous pronoun use. Centering theory provides the basis for such an integrated approach. Generating coherent texts according to centering theory is treated as a constraint satisfaction problem. The well-known Rule 2 of centering theory is reformulated in terms of a set of constraints—cohesion, salience, cheapness, and continuity—and we show sample outputs obtained under a particular weighting of these constraints. This framework facilitates detailed research into evaluation metrics and will therefore provide a productive research tool in addition to the immediate practical benefit of improving the fluency and readability of generated texts. The technique is generally applicable to natural language generation systems, which perform hierarchical text structuring based on a theory of coherence relations with certain additional assumptions.
- Florian Wolf, Edward Gibson. 2005. Representing Discourse Coherence: A Corpus-Based Study. Computational Linguistics, Vol. 31, No. 2, pp. 249–287. pdf
Abstract
This article aims to present a set of discourse structure relations that are easy to code and to develop criteria for an appropriate data structure for representing these relations. Discourse structure here refers to informational relations that hold between sentences in a discourse. The set of discourse relations introduced here is based on Hobbs (1985). We present a method for annotating discourse coherence structures that we used to manually annotate a database of 135 texts from theWall Street Journal and the AP Newswire. All texts were independently annotated by two annotators. Kappa values of greater than 0.8 indicated good interannotator agreement. We furthermore present evidence that trees are not a descriptively adequate data structure for representing discourse structure: In coherence structures of naturally occurring texts, we found many different kinds of crossed dependencies, as well as many nodes with multiple parents. The claims are supported by statistical results from our hand-annotated database of 135 texts.
- Rashmi Prasad, Nikhil Dinesh, Alan Lee, Eleni Miltsakaki, Livio Robaldo, Aravind Joshi, Bonnie Webber. 2008. The Penn Discourse TreeBank 2.0. In Proceedings of the 6th International Conference on Language Resources and Evaluation (LREC 2008) http://www.seas.upenn.edu/~pdtb/papers/pdtb-lrec08.pdf
Abstract
We present the second version of the Penn Discourse Treebank, PDTB-2.0, describing its lexically-grounded annotations of discourse
relations and their two abstract object arguments over the 1 million word Wall Street Journal corpus. We describe all aspects of the
annotation, including (a) the argument structure of discourse relations, (b) the sense annotation of the relations, and © the attribution
of discourse relations and each of their arguments. We list the differences between PDTB-1.0 and PDTB-2.0. We present representative
statistics for several aspects of the annotation in the corpus.