Incremental Interpretation: Applications, Theory, And Relationship To Dynamic Semantics

Why should computers interpret language incremen-tally? In recent years psycholinguistic evidence for in-cremental interpretation has become more and more compelling, suggesting that humans perform semantic interpretation before constituent boundaries, possibly word by word. However, possible computational applications have received less attention. In this paper we consider various potential applications, in particular graphical interaction and dialogue. We then review the theoretical and computational tools available for mapping from fragments of sentences to fully scoped semantic representations. Finally, we tease apart the relationship between dynamic semantics and incremental interpretation. it has become widely accepted that semantic interpretation in human sentence processing can occur before sentence boundaries and even before clausal boundaries. It is less widely accepted that there is a need for incremental interpretation in computational applications. In the 1970s and early 1980s several computational implementations motivated the use of incremental interpretation as a way of dealing with structural and lexical ambiguity (a survey is given in Haddock 1989). A sentence such as the following has 4862 different syntactic parses due solely to attachment ambiguity (Stabler 1991). 1) I put the bouquet of flowers that you gave me for Mothers' Day in the vase that you gave me for my birthday on the chest of drawers that you gave me for Armistice Day. Although some of the parses can be ruled out using structural preferences during parsing (such as Late Closure or Minimal Attachment (Frazier 1979)), extraction of the correct set of plausible readings requires use of real world knowledge. Incremental interpretation allows on-line semantic filtering, i.e. parses of initial fragments which have an implausible or * anomalous interpretation are rejected, thereby preventing ambiguities from multiplying as the parse proceeds. However, on-line semantic filtering for sentence processing does have drawbacks. Firstly, for sentence processing using a serial architecture (rather than one in which syntactic and semantic processing is performed in parallel), the savings in computation obtained from on-line filtering have to be balanced against the additional costs of performing semantic computations for parses of fragments which would eventually be ruled out anyway from purely syntactic considerations. Moreover, there are now relatively sophisticated ways of packing ambiguities during parsing (e.g. by the use of graph-structured stacks and packed parse forests (Tomita 1985)). Secondly, the task of judging plausibility or anomaly according to context and real world knowledge is a difficult problem , except in some very limited domains. In contrast, statistical techniques using …