Rules have traditionally been used in theoretical computer science, compiler technology, databases, logic programming, and AI. The Semantic Web is a new W3C Activity trying to represent information in the World Wide Web such that it can be used by machines not just for display purposes, but for automation, integration, and reuse across applications. Rule markup in the Web has become a hot topic since rules were identified as a design issue of the Semantic Web. However, rule markup for the Semantic Web has not been studied as systematically as the corresponding ontology markup. This Dagstuhl Seminar was an attempt to fill the gap by bringing together researchers exploring rule systems suitable for the Web, their (XML and RDF) syntax, semantics, tractability/efficiency, and transformation/compilation. Both derivation rules (also called “inference rules”) and state-changing reaction rules (also called "active" or "event-condition-action" rules), as well as any combinations, have been of interest to this effort.

This seminar has succeeded in bringing together leading researchers from the classical logic programming and knowledge representation community and from the Semantic Web community. The discussions at the seminar have been very productive, both scientifically and in terms of triggering new research activities such as a EU FP6 Network of Excellence initiative.