tailieunhanh - Báo cáo khoa học: "An Underspecified Segmented Discourse Representation Theory (USDRT)"

A theory of discourse interpretation has to deal with a set of problems including anaphora resolution and the hierarchical ordering of discourse structure: (1) Several students organised a dinner party for Peter. Some students wrote fancy invitation cards. Some other students bought exotic food. But Peter didn't like it. | An Underspecified Segmented Discourse Representation Theory USDRT Frank Schilder Computer Science Department Hamburg University Vogt-Kolln-Str. 30 D-22527 Hamburg Germany schilder@ 1 Introduction A theory of discourse interpretation has to deal with a set of problems including anaphora resolution and the hierarchical ordering of discourse structure 1 Several students organised a dinner party for Peter. Some students wrote fancy invitation cards. Some other students bought exotic food. But Peter didn t like it. There are two conceivable readings for 1 . Either a it refers to the party or b Peter only disliked the food. Discourse grammars like Segmented Discourse Representation Theory SDRT offer an explanation for this phenomenon. SDRT an extension of DRT Kamp and Reyle 1993 describes a complex propositional structure of Discourse Representation Structures DRSs connected via discourse relations. The hierarchical ordering imposed by relations like narration or elaboration can be used to make predictions about possible attachment sites within the already processed discourse as well as suitable antecedents of anaphora. The next section discusses the question of whether the SDRT formalisation used for discourse structure should also capture the ambiguities as expressed in 1 for instance via an underspecified representation. Section 3 introduces a tree logic proposed by Kallmeyer called TDG. Following Schilder 1997 this formalism is employed for the representation of the discourse structure. Section 4 presents the conjoined version of SDRT and TDG. This is a novel combination of the discourse grammar and a tree logic indicating the hierarchical discourse structure. Finally a USDRT formalisation of the discourse example discussed is given. 2 From DRT to SDRT One obvious shortcoming DRT is that it lacks the rhetorical information that structures the text. This rhetorical information expressed by discourse relations such as narration or background .