Logic for Data Description

Abstract

Logic is useful both for describing static data bases as well as for processing data bases which change. Both the static and dynamic management of data bases depends upon the form of definitions: whether data is defined by means of complete if-and-only-if definitions or only by means of the if-halves, whether the only-if half of an if-and-only-if definition is stated explicitly or is assumed implicitly, and whether the only-if assumption is understood as a statement of the object language (in the data base) or as a statement of the meta-language (about the data base). Similar considerations apply to the processing of computer programs. When logic is used to describe information, the conventional distinction between data bases and programs no longer applies.