tailieunhanh - Báo cáo khoa học: "Entity-based local coherence modelling using topological fields"

One goal of natural language generation is to produce coherent text that presents information in a logical order. In this paper, we show that topological fields, which model high-level clausal structure, are an important component of local coherence in German. First, we show in a sentence ordering experiment that topological field information improves the entity grid model of Barzilay and Lapata (2008) more than grammatical role and simple clausal order information do, particularly when manual annotations of this information are not available. . | Entity-based local coherence modelling using topological fields Jackie Chi Kit Cheung and Gerald Penn Department of Computer Science University of Toronto Toronto ON M5S 3G4 Canada jcheung gpenn @ Abstract One goal of natural language generation is to produce coherent text that presents information in a logical order. In this paper we show that topological fields which model high-level clausal structure are an important component of local coherence in German. First we show in a sentence ordering experiment that topological field information improves the entity grid model of Barzilay and Lapata 2008 more than grammatical role and simple clausal order information do particularly when manual annotations of this information are not available. Then we incorporate the model enhanced with topological fields into a natural language generation system that generates constituent orders for German text and show that the added coherence component improves performance slightly though not statistically significantly. 1 Introduction One type of coherence modelling that has captured recent research interest is local coherence modelling which measures the coherence of a document by examining the similarity between neighbouring text spans. The entity-based approach in particular considers the occurrences of noun phrase entities in a document Barzilay and Lap-ata 2008 . Local coherence modelling has been shown to be useful for tasks like natural language generation and summarization Barzilay and Lee 2004 and genre classification Barzilay and Lap-ata 2008 . Previous work on English a language with relatively fixed word order has identified factors that contribute to local coherence such as the grammatical roles associated with the entities. There is good reason to believe that the importance of these factors vary across languages. For instance freer-word-order languages exhibit word order patterns which are dependent on discourse factors relating to information structure