The Syntactic Web

XQuery is a query language designed to allow queries across the many kinds of information that are represented in XML. Although topic maps and RDF can also be represented in XML, many have held that their many possible syntactic forms make them extremely difficult to query using an XML query language, and that they can only be queried using special-purpose query languages with built-in knowledge of their semantics, including the ability to exploit RDF schema information. This talk shows that XQuery can, in fact, be used to solve the kinds of queries for which RDF and topic map query languages were designed, though with a loss of type safety. The approach taken is to transform instances of RDF and topic maps to a syntactic representation that closely models their underlying logical models, and to use function libraries written in XQuery to directly support operations specific to RDF or topic maps. Schema level information is also incorporated in this representation, and is supported in the library, so queries can exploit type hierarchies and perform joins across predicates. Information from other XML sources can also be queried together with information from topic maps and RDF. For instance, a query on a topic maps that searches for Shakespeare plays mentioned in Italian operas can also query the plays themselves -represented in XML -to determine which Italian cities are mentioned in them. Syntax is not the opposite of semantics, it is a medium for semantics.