Effective integration of declarative rules with external evaluations for semantic-Web reasoning

Abstract

Towards providing a suitable tool for building the Rule Layer of the Semantic Web, HEX-programs have been introduced as a special kind of logic programs featuring capabilities for higher-order reasoning, interfacing with external sources of computation, and default negation. Their semantics is based on the notion of answer sets, providing a transparent interoperability with the Ontology Layer of the Semantic Web and full declarativity. In this paper, we identify classes of HEX-programs feasible for implementation yet keeping the desirable advantages of the full language. A general method for combining and evaluating sub-programs belonging to arbitrary classes is introduced, thus enlarging the variety of programs whose execution is practicable. Implementation activity on the current prototype is also reported. © Springer-Verlag Berlin Heidelberg 2006.