The Impact of Syntax on the Interpretation and Graphical Depiction of Underspecified Propositions - eScholarship (2010)

The Impact of Syntax on the Interpretation and Graphical Depiction of Underspecified Propositions Aaron Kalb, Dave Barker-Plummer 1 , Deonne Castaneda, Christopher Potts 2 Stanford University, Stanford, CA 94305 USA {kalb,dbp,deonne,cgpotts}@stanford.edu Richard Cox School of Informatics, University of Sussex Falmer, E. Sussex, BN1 9QJ, UK richc@sussex.ac.uk Robert Dale Center for Language Technology, Macquarie University Sydney, NSW 2109, Australia rdale@science.mq.edu.au Abstract The second observation we take as a starting point is that natural language affords multiple ways of realizing the same semantic content. This is often exemplified by reference to the fact that active and passive sentences, such as Fred wrote the book and The book was written by Fred, describe the same state of affairs. There may be contextual, or pragmatic, reasons for choosing one realization over the other, as com- monly discussed under the heading of information packag- ing (Vallduvi, 1992); but the common view is that the seman- tics of the two sentences, in terms of propositional content, is the same. Different representational systems permit differing degrees and forms of ambiguity and underspecification in the content they represent. Independently of this observation, a notable feature of natural language as a representational system is that it allows the same content to be expressed in different ways. In this paper, we examine the interaction of these two obser- vations; in particular, we explore a number of linguistic forms involving underspecified content, and look at how subjects ex- press the content of these linguistic forms both in logic and in diagrams. Our analysis demonstrates that variations in syntac- tic realization of the same semantic content lead to different interpretations of that content. Keywords: logic; natural language; syntactic structure; dia- grams; representations; negation. We are interested in how these two phenomena inter- act. Our interest is motivated by an effect found in an earlier study (Cox, Dale, Etchemendy, & Barker-Plummer, 2008), in which the specificity of participants’ responses to NL sentences containing negation differed markedly between their FOL translations and their diagrammatic interpretations. Specifically, it was found that in their FOL translations of the sentence d is not a small dodecahedron, participants over- whelmingly treated the predicates small and dodecahedron symmetrically, whereas their diagrams of the sentence tended to make d a dodecahedron that isn’t small, rather than a small shape other than a dodecahedron. However, contextual con- founds made the source of this effect hard to establish. Introduction This paper takes as its starting point two widely-made ob- servations. First, different representational systems permit different abstractions, and consequently, they permit under- specification on different dimensions. In particular, natu- ral language ( NL ) and first-order logic ( FOL ) are two rep- resentational systems that permit underspecification of as- pects of meaning that must be made explicit in diagram- matic representations. Direction is a case in point: consider the natural language statement The house is adjacent to the park; neither this sentence, nor a typical FOL rendering such as AdjacentTo(house, park), specifies the direction of adja- cency, but a picture or diagrammatic rendering of the sentence must make this explicit. We will say that the NL represen- tation of the state of affairs is underspecified with respect to the diagrammatic representation. This makes it clear that underspecification as defined here is a relational notion; how- ever, for convenience in the remainder of this paper we will simply refer to representations as being underspecified when the relatum is obvious from the context. 1 Center In this paper, we report on an experiment which sought to elucidate the effects of different possible factors on this phenomenon. In particular, we ask: if we have a number of natural language forms that express the same underspecified semantic content, what happens when subjects are asked to draw diagrams that require them to be more explicit? If the NL sentences truly express the same meaning, then we might expect to see similar distributions of the possible diagram- matic renderings, regardless of the NL surface form used. Alternatively, syntax or semantics may make some diagram- matic renderings more salient or available than others, This paper sets out to determine which of these alternatives hold. for the Study of Language and Information. of Linguistics. 2 Department