Pragmatic Overloading in Natural Language Instructions

It has long been noted that Natural Language utterances can communicate more than their conventional meaning (Grice, 1975). It has also been noted that behaving appropriately in response to instructions given in Natural Language requires understanding more than their conventional meaning This paper addresses one mechanism by which speakers convey, and hearers derive, such additional aspects of meaning { a mechanism we call pragmatic overloading. In pragmatic overloading, a clause interpreted as conveying directly or indirectly the goal of an action which is described by some other clause, forms the basis of constrained inference that leads to additional information about the action. The paper demonstrates pragmatic overloading through a variety of clausal adjuncts. We then discuss a framework that supports many of the inferences that pragmatic overloading gives rise to. This framework integrates a lexical semantics representation a la Jackendoo (1990) with a knowledge representation system, CLASSIC (Brachman et al., 1991), based on description logic. We give examples of its use, before concluding with a discussion of future work.