Foundations of a Functional Approach to Knowledge Representation

Abstract We present a new approach to knowledge representation where knowledge bases are characterized not in terms of the structures they use to represent knowledge, but functionally, in terms of what they can be asked or told about some domain. Starting with a representation system that can be asked questions and told facts in a full first-order logical language, we then define ask- and tell-operations over an extended language that can refer not only to the domain but to what the knowledge base knows about that domain. The major technical result is that the resulting knowledge, which now includes auto-epistemic aspects, can still be represented symbolically in first-order terms. We also consider extensions to the framework such as defaults and definitional facilities. The overall result is a formal foundation for knowledge representation which, in accordance with current principles of software design, cleanly separates functionality from implementation structure.