An approach to abductive inference developed in the TACITUS project has resulted in a dramatic simplification of how the problem of interpreting texts is conceptualized. Its use in solving the local pragmatics problems of reference, compound nominals, syntactic ambiguity, and metonymy is described and illustrated. It also suggests an elegant and thorough integration of syntax, semantics, and pragmatics. 1

Many seemingly very different application tasks for natural language systems can be viewed as a matter of inferring the instance of a prespecified schema from the information in the text and the knowledge base. We have defined and implemented a schema specification and recognition language for the TACITUS natural language system. This effort entailed adding operators sensitive to resource bounds to the first-order predicate calculus accepted by a theorem-prover. We give examples of the use of this schema language in a diagnostic task, an application involving data base entry from messages, and a script recognition task, and we consider further possible developments.

The outline of a unified theory of local pragmatics phenomena is presented, including an approach to the problems of reference resolution, metonymy, and interpreting nominal compounds, and the TACITUS system embodying this theory is described. The theory and system are based on the use of a theorem prover to draw the appropriate inferences from a large knowledge base of commonsense and technical knowledge. Issues of control and minimality are discussed.