RWTH Aachen University
SPARQL is the standard query language for RDF (Resource Description Framework) data. However, its application to linked data is challenging because the assumption that all necessary data is present at the beginning of the evaluation does not apply. Some relevant data sources may only be discovered by processing available data. Existing approaches provide implementations that compute results for basic graph patterns incrementally while retrieving the data. The authors contribute to this area by a formal analysis of the SPARQL algebra to provide incremental adaptions of the operations.