Fuzzy RDF Queries

Abstract

AbstractAn increasing amount of data is becoming available in RDF format. Developing applications that interact with RDF data has attracted considerable attention, among which RDF data retrieval is one of the most important applications. In particular, since RDF data have a natural representation in the form of a graph, this problem has been often addressed in terms of graph matching between a small graph representing the query and a very large graph representing the database. The RDF graph matching algorithm becomes the technical foundation of many tasks in Semantic Web, such as semantic search, data fusion, ontology matching, data filter and dissemination. However, the RDF fall short in their ability to handle imprecise and uncertain information in many real-world applications, and also the relevant RDF query techniques cannot support subgraph pattern query in fuzzy RDF. Currently, fuzzy RDF data modeling has been extensively investigated as introduced in Chap. 3. Therefore, topics related to the querying of fuzzy RDF can be considered very interesting in the fuzzy RDF data context. In this chapter, we focus on the construction of the fuzzy RDF query method of graph pattern matching and the fuzzy extension mechanism of SPARQL query language. First, we present a graph pattern matching algorithm based on a revised notion of graph homomorphism in a fuzzy RDF graph. Specifically, we want to retrieve all qualified matches of a query pattern in the fuzzy RDF graph. Then, we investigate a novel path-based solution to retrieve subgraph from fuzzy RDF graph databases. Next, we integrate fuzzy quantified statements in fuzzy RDF queries addressed to a fuzzy RDF database. We present an approach to summarize fuzzy RDF graph database in the form of linguistic summaries, and we have showed how these statements can be defined and implemented. Finally, we present an extension of SPARQL to query fuzzy RDF graph. The extension is able to express fuzzy queries making use of regular expressions and fuzzy conditions.