Two approaches to merging knowledge bases

Abstract

We present a framework for expressing different merging operators for belief sets. This framework is a generalisation of our earlier work concerning consistency-based belief revision and contraction. Two distinct merging operators are identified: in the first approach, belief sources are consistently combined so that the result of merging knowledge bases K1,..., Kn is a maximal consistent (if possible) set of formulas comprising the joint knowledge of the knowledge bases. This approach then accords to one's intuitionsasto what a "merge" operator should do. The second approach is more akin to a generalised belief revision operator: Knowledge bases K1,..., Kn are "projected" onto another (in the simplest case the trivially true knowledge base). In both cases, we consider the incorporation of entailment-based and consistency-based integrity constraints. Properties of these operators are investigated, primarily by comparing their properties with postulates that have been identified previously in the literature.As well, the interrelationships between these approaches and belief revision is given.