The Role of Inversion and PP-Fronting In Relating Discourse Elements: some implications for cognitive and computational models of Natural Language Processing

The Role of Inversion and PP-Fronting In Relating Discourse Elements: some implications for cognitive and computational models of Natural Language Processing Mark Vincent LaPnlla The Artificial Intelligence Laboratory and The Department of Linguistics University of Texas at Austin, Austin, Texas USA 11 April 1986 O. Abstract 1 This paper will explore and discuss the less obvious ways syntactic structure is used to convey information and how this information could be used by a natural language database system as a heuristic to organize and search a discourse space. The primary concern of this paper will be to present a general theory of processing which capitalizes on the information provided by such non-SVO word orders as inversion, (wh) clcfting and prepositional phrase (PP) fronting. since it seems that these non-SVO structures are sensitive to NPs. Thus every discourse representation is in some way redundantly specified for at least one constituent. For example, the organization of the discourse representation for the sentences, "In the forest stood a house" and "In the park, Mary kissed John", are: Labcl: house, forest D.R. : a house stood in the forest and 1. Introduction English at its simplest is an SVO, Subject Verb Object, language. However it is not limited to SVO order. Clefts, pseudo-clefts, inversion, topicalization, left dislocation and various types of fronting are instances of deviation from SVO order. Non-SVO orders are not exceptional or found only in obscure literary writing. They abound throughout writing and speech. An interesting question is what use do these structures do in English, and how can a cognitive or computational theory use such information? Non-SVO word order helps the reader (or listener) to construct a discourse representation. It is a heuristic devise for creating coherent and cohesive representations of text and for searching existing representations. In other words, it is a device for finding in long or medium term memory the relevant context, or discourse space, in which to embed and interpret the sentence being processed. It is a linguistic device used for changing the discourse focus (Sidncr 1978, 1983; Grosz 1978, 1981). It is important to note that no particular discourse representation construction schema is assumed in this claim but rather that this claim holds no matter what type of construction algorithm is used. Also, what is being proposed here is not a linguistic rule for constructing discourse representation but rather a principle (heuristic) for constructing them. That is a principle for organizing and searching discourse representations. As a sentence is processed a representation is made of it. This representation consists of a label, which is a (syntactic and semantic) parse 2 of the first constituent cncountercd, followed by a parse of the whole sentence. Actually, one could have multiple labels that consisted of the NPs in the sentence, 1This research was supported by the U.S. Army Research Office under contract DAAG29-84-K-0060. Artificial Intelligence Laboratory, Department of Computer Sciences. I would like to thank Professor Robert F. Simmons for his support, help and criticisms. 2The exact representation of …

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