A Contribution to the Semantics of Xcerpt, a Web Query and Transformation Language

Xcerpt [1,2] is a declarative and pattern-based query and transformation language for the Web with deductive capabilities. In contrast to Web query languages like XQuery and XSLT [3,4], Xcerpt relies on concepts and techniques from logic programming and automated theorem proving such as declarative “query patterns” and “rule chaining”. Xcerpt can also be used for querying Web metadata, like OWL or RDF data [5,6], and reasoning on such metadata. In contrast to specific languages for OWL and RDF, however, Xcerpt is a general purpose query, transformation, and reasoning language, i.e. it can be used for reasoning not only with Web metadata but also with plain Web data.