### From Semantic Web Technologies

From Chapter 5

# OWL Formal Semantics

of Foundations of Semantic Web Technologies:

In Chapter 4 we introduced OWL syntactically, and have discussed intuitively how to derive logical inferences from OWL ontologies. This derivation of implicit knowledge is at the heart of logic-based semantics, and we give this a thorough and formal treatment in this chapter. We start with description logics in Section 5.1, which provide a logical view on OWL. In Section 5.2, we then present two equivalent ways of defining the formal semantics of OWL. In Section 5.3 we present the most successful algorithmic approach, the so-called tableaux method, for automated reasoning with OWL ontologies. In this chapter, the reader will benefit from some background in predicate logic, which can be found in Appendix C.

## Contents

- Description Logics
- Model-Theoretic Semantics of OWL
- Automated Reasoning with OWL
- Summary
- Exercises
- Further Reading