Utilizing Host-Formalisms to Extend RDF-Semantics

RDF may be considered as an application of XML intended to interoperably exchange semantics between Web applications. In its current form, this objective may be hard to reach. Even if the semantical gems hidden in the RDF/RDFS specification are precisely captured, as, for example, in the axiomatic formalizations currently available, the useabilty of RDF’s concepts and constraints is limited: RDF offers a data model but does not specify the processing of RDF-encoded data. RDFS describes some basic (ontological) concepts and constraints but does not specify the processing of RDFS-encoded ontological information. The expressiveness of the constraints is rather limited and no clear means of providing semantics for new concepts and constraints are specified. This paper presents one possible approach to overcome this weaknesses. The definition and interpretation of semantics and the processing of the RDF-encoded information will be delegated to a host formalism (first order logic). An elaborated example specifies an extended set-algebraic range constraint and applies the extended vocabulary to a security management task. The definition of semantics is made explicit in the RDF Schemata. The new constraints and concepts are added to the concepts and constraints of an underlying axiomatic interpretation of RDF(S). A Prolog-based implementation of the approach, the RDF Schema Explorer, which is available on-line, is presented. The tool allows to process, validate, query and extend a FOL interpretation of (extended) RDF Schemata.1