Complex path queries for RDF graphs
Faisal Qaseem Alkhateeb, Jean-François Baget, Jérôme Euzenat · 2005
RDF entailment [5], and by extension RDF queries, can be computed using a kind of graph homomorphism known as conceptual graphs projection [3]. Another approach, that has been successfully used in graph databases [6], is to use regu-lar expressions to nd paths in a graph (i.e., given a directed labeled graph G and a regular expression E, nd all pairs of nodes connected by a path such that the concatenation of the labels along the path belongs to the language generated by E, denoted by L¤(E)). However, some queries that can be expressed in one approach cannot be expressed in the other. A query whose homomorphic image in the database is not a path cannot be expressed by a regular expression, while RDF semantics is not meant to express paths of unknown length. To benet from both approaches, we present an extension