Issues in Natural Language Access to Databases from a Logic Programming Perspective

corresponding roughly to: "What does the question mean?", "How shall I answer it?", "What is the answer?". The meaning of a NL question, and the database of information about the application domain, are both represented as statements in an extension of a subset of flrst-order logic, which we call "definite closed world" (DCW) logic. This logic is a subset of flrst-order logic, in that it admits only "definite" statements; uncertain information ("Either this or that") is not allowed. DCW logic extends flrst-order logic, in that it provides constructions to support the "closed world" assumption, that everything not known to be true is false.