PRAGMATIC OVERLOADING IN NATURAL-LANGUAGE INSTRUCTIONS

It has long been noted that Natural Language utterances can communicat e more than their conventional meaning (Grice, 1975). It has also been noted that behaving appropriately in response to instructions given i n Natural Language requires understanding more than their conventional meaning (Suppes & Crangle, 1988; Webber & Di Eugenio, 1990; Webber et al., 1992). This paper addresses one mechanism by which speakers conv ey, and hearers derive, such additional aspects of meaning - a mechani sm we call pragmatic overloading. In pragmatic overloading, a clause i nterpreted as conveying directly or indirectly the goal beta of an act ion alpha which is described by some other clause, forms the basis of constrained inference that leads to additional information about the a ction alpha. The paper demonstrates pragmatic overloading through a va riety of clausal adjuncts. We then discuss a framework that supports m any of the inferences that pragmatic overloading gives rise to. This f ramework integrates a lexical semantics representation a la Jackendoff (1990) with a knowledge representation system, CLASSIC (Brackman et a l., 1991) based on description logic. We give examples of its use, bef ore concluding with a discussion of future work.