A Semantic Web Reasoner for Rules, Equations and Constraints

We describe a reasoner for OWL ontologies and SWRL policies used on cognitive radios to control dynamic spectrum access. In addition to rules and ontologies, the reasoner needs to handle user-defined operations (e.g., temporal and geospatial). Furthermore, the reasoner must perform sophisticated constraint simplification because any unresolved constraints can be used by a cognitive radio to plan and reason about its spectrum usage. No existing reasoner supported all these features. However, the term rewriting engine Maude, augmented with narrowing, provides a promising reasoning mechanism. This allows for a behavior similar to that of a logic programming system, while constraint simplification rules as well as operations can easily be defined and processed. Our system and general approach will be useful for other problems that need sophisticated constraint processing in addition to rule-based reasoning, or where new operations need to be added. The implementation is efficient enough to run on resource-constrained embedded systems such as software-defined radios.