Summary.Although real-scale Semantic Web applications, such as Knowledge Portals and E-Marketplaces, require the management of voluminous resource metadata, sufficiently expressive declarative languages for metadata created according to the W3C RDF /S standard l are still missing. In answer to this need, we have designed a typed, functional query language, called RQL, whose novelty lies in its ability to smoothly combine schema and data querying. The purpose of this chapter is to present RQ L's formal data model and type system and illustrate its expressiveness by means of exemplary queries. RQL's formal foundations capture the RDF /S modeling primitives and provide a well-founded semantics for a declarative query language involving recursion and functional composition over complex description graphs. IntroductionIn the next evolutionary step of the Web, termed the Semantic Web [18.5], vast amounts of information resourees (data, doeuments, programs, ete.) will be made available along with various kinds of deseriptive information, i.e.,

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