A Logical Model of Updates of Knowledge Bases

Abstract

In this paper we propose a natural and general model of updates of knowledge bases, where we represent a knowledge as a closed formula of first-order logic and consider a knowledge bases a theory. For this purpose, we extend the model of updates of theories proposed by Fagin et al., and define the join of theories. Furthermore we extend the concept of join to treat logical databases of Fagin et al., and show that we can formulate the concept of insertion as a special case of the join of logical databases. We also give an example of updates of a knowledge base to illustrate our ideas. This model gives the semantics of the update of knowledge bases and will work as a basic model for investigating the behavior of the knowledge base management systems.