ABSTRACT

The main mechanism for computing query results in SPARQL is subgraph matching: RDF triples in both the queried RDF data and the query pattern are interpreted as nodes and edges of directed graphs, and the resulting query graph is matched to the data graph using variables as wild cards. An en-tailment regime defines only which entailment relation is used, but also which queries and graphs are well-formed for the regime, how the entailment is used, or what kinds of errors can arise. The main mechanism for computing query results in SPARQL is subgraph matching: RDF triples in both the queried RDF data and the query pattern are interpreted as nodes and edges of directed graphs, and the resulting query graph is matched to the data graph using variables as wild cards. The notion of answer and answer set of a disjunctive query is a straightforward extension of the ones for conjunctive queries.