Web and Semantic Web Query Languages

A number of techniques have been developed to facilitate powerful data retrieval on the Web and Semantic Web. Three categories of Web query languages can be distinguished, according to the format of the data they can retrieve: XML, RDF and Topic Maps. This article introduces the spectrum of languages falling into these categories and summarises their salient aspects. The languages are introduced using common sample data and query types. Key aspects of the query languages considered are stressed in a conclusion

Proceedings of the 19th International Workshop on Unification

Proceedings of the 19th international workshop on Unification, held during RDP'2005 in Nara, Japan, on April 22, 2005.UNIF is the main international meeting on unification. Unification is concerned with the problem of identifying given terms, either syntactically or modulo a given logical theory. Syntactic unification is the basic operation of most automated reasoning systems, and unification modulo theories can be used, for instance, to build in special equational theories into theorem provers

BINARY QUERIES FOR DOCUMENT TREES

Motivated by XML applications, we address the problem of answering k-ary queries, i.e. simultaneously locating k nodes of an input tree as specified by a given relation. In particular, we discuss how binary queries can be used as a means of navigation in XML document transformations. We introduce a grammar-based approach to specifying k-ary queries. An efficient tree-automata based implementation of unary queries is reviewed and the extensions needed in order to implement k-ary queries are presented. In particular, an efficient solution for the evaluation of binary queries is provided and proven correct. We introduce fxgrep, a practical implementation of unary and binary queries for XML. By means of fxgrep and of the fxt XML transformation language we suggest how binary queries can be used in order to increase expressivity of rule-based transformations. We compare our work with other querying languages and discuss how our ideas can be used for other existing settings