Marrying stable models with belief update

The need for integration of classical logic with nonmonotonic rules has been gaining importance in areas like the Semantic Web and Open Multi-Agent Systems. A number of researchers addressed this problem by proposing a unified semantics for knowledge bases composed of both first-order formulae and rules (also called hybrid knowledge bases). These semantics have matured over the years, but only provide solutions for the static case when knowledge does not need to evolve. In this paper we take a first step towards addressing the dynamics of hybrid knowledge bases. Considering the results from the complementary areas of belief update and rule update, we focus on a scenario where rules can be used to describe the static background knowledge and reasoning of an agent, and the information about the current state of the world, encoded in classical logic, may evolve through time. We propose an update operator for this scenario and study its basic properties. To the best of authors’ knowledge, this is the first time results of both branches of research on updates are combined to design an update operator for a hybrid knowledge base.