Ontology schema for an agent belief store

Abstract

In this paper we explore the use of a formal ontology as a constraining framework for the belief store of a rational agent. The static beliefs of the agent are the axioms of the ontology. The dynamic beliefs are the descriptions of the individuals that are instances of the ontology classes. The individuals all have a unique identifier, an associated set of named classes to which they are believed to belong, and a set of property values. The ontology axioms act as a schema for the dynamic beliefs. Belief updates not conforming to the axioms lead to either rejection of the update or some other revision of the dynamic belief store to maintain consistency. Partial descriptions are augmented by inferences of property values and class memberships licensed by the axioms. For concreteness we sketch how such an ontology based agent belief store could be implemented in a multi-threaded logic programming language with action rules and object oriented programming features called Go!. This language was specifically designed for implementing communicating rational agent applications. We shall see that its logic rules allow us to extend an ontology of classes and properties with rule defined n-ary relations and functions. Its action rules enable us to implement a consistency maintenance system that takes into account justifications for beliefs. The pragmatics of consistency maintenance is an issue not normally considered by the ontology community. The paper assumes some familiarity with ontology specification using languages such as OWL DL and its subsets, and with logic programming.