I. Introduction It is impractical for natural language parsers which serve as front ends to large or changing databases to maintain a complete in-core lexicon of words and meanings. This note discusses a practical approach to using alternative sources of lexical knowledge by postponing word categorization decisions until the parse is complete, and resolving remaining lexical anthiguities usiug a variety of informatkm available at that time. il. The Problem A natutal language parser working with a database query system ( PLANES [Waltz et al, 1976], LADDER [Hcndrix, 1977], ROBOT [Harris, 1977], CO-OP [Kaplan, 19791) encounters lexical diflicultics not present.
